Simulation-Based Design for Recycling of Car Electronic Modules as a Function of Disassembly Strategies

van Schaik, Antoinette; Reuter, Markus A.

doi:10.3390/su16209048

Open AccessArticle

Simulation-Based Design for Recycling of Car Electronic Modules as a Function of Disassembly Strategies

by

Antoinette van Schaik

^1,*

and

Markus A. Reuter

²

¹

Material Recycling and Sustainability B.V. (MARAS B.V.), 2498 AS Den Haag, The Netherlands

²

WASM: Minerals, Energy and Chemical Engineering, Curtin University, Perth 6102, Australia

^*

Author to whom correspondence should be addressed.

Sustainability 2024, 16(20), 9048; https://doi.org/10.3390/su16209048

Submission received: 16 August 2024 / Revised: 6 October 2024 / Accepted: 14 October 2024 / Published: 18 October 2024

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Abstract

:

Modules (or parts) of a car are a complex functional material combination used to deliver a specified task for a car. Recovering all materials, energy, etc., into high-grade materials at their end of life (EoL) is impossible. This is dictated by the second law of thermodynamics (2LT) and thence economics. Thus, recyclability cannot be conducted with simplistic mass-based approaches void of thermodynamic considerations. We apply, in this paper, a process simulation model to estimate the true recyclability of various SEAT (Volkswagen Group) car parts within the EU H2020 TREASURE project. This simulation model is developed with 190 reactors and over 310 feed components with over 1000 reaction species in the 880 streams of the flowsheet. The uniqueness of the work in this paper is to apply the full material declaration (FMD) and bill of materials (BOM) of all 310 materials in the parts as a feed to the process simulation model to show the parts’ true recyclability. We classified all parts into categories, i.e., copper-rich, steel-rich and plastic-rich, to maximally recover metals at the desired material quality, as well as energy. Recyclability is understood to create high-grade products that can be applied with the same functional quality in these parts. In addition, disassembly strategies and related possible redesign show how much recyclability can be improved. Process simulation permits the creation of alloys, phases, materials, etc., at a desired quality. The strength of the simulation permits any feed from any End-of-Life part to be analyzed, as long as the FMD and BOM are available. This is analogous to any mineral and metallurgical engineering process simulation for which the full mineralogy must be available to analyze and/or design flowsheets. This paper delivers a wealth of data for various parts as well as the ultimate recovery of materials, elements, and energy. The results show clearly that there is no one single recycling rate for elements, materials, and alloys. It is in fact a function of the complexity and material combinations within the parts. The fact that we use a thermochemical-based process simulator with full compositional detail for the considered parts means full energy balances as well as exergy dissipation can be evaluated. This means that we can also evaluate which parts, due complex mixtures of plastics, are best processed for energy recovery or are best for material and metal recovery, with thermochemistry, reactor technology and integrated flowsheets being the basis.

Keywords:

design for recycling; process simulation-based analysis; metallurgy; recycling rates; circular economy

1. Introduction

The circular economy (CE) paradigm aims to transform the economy from linear to circular models, in which as many materials as possible, both waste and recycled, are potential resources, obviously within economic constraints. The Europe 2020 strategy declares “Natural resources underpin the functioning of the European and global economy and our quality of life”. The key objective of this is to achieve a resource efficiency (RE)-conscious, resilient society that champions a CE [1,2,3]. The automotive industry is, like many other industries, taking steps to move to a more CE. This is driven by increasing environmental constraints as well as the need to reduce resource dependency in industries by keeping (secondary) raw materials in the circle within European boundaries. A CE aims to maximize resource efficiency (RE) by extending the product lifetime, repair and reuse, the use of waste and End-of-Life (EoL) products as resources and the repurposing of recycled materials as recycled content in new products. The European Commissions’ focus on CE includes the increased recovery of Critical Raw Materials (CRMs) from automotive electronics and their foreseen reapplication in these products. This is also envisaged in the draft of the upcoming End-of-Life Vehicle (ELV) directive, which forces industries to embrace and investigate new concepts in EoL treatment, not only for recovering bulk materials from EoL products (e.g., vehicles) but also to improve the recovery of CRMs.

The realization of circularity through the recycling of materials requires that a product’s materials are being recycled into functional materials with the highest possible quality, which can be applied in the same product. Present and future society is characterized by extremely intensive production and consumption patterns. This results in vast and increasing amounts of waste and consumer goods with complex functional material combinations. The complexity of products such as vehicles and electronics and their multi-material nature combining many functional materials are challenging the viability of the CE despite various alternative business models promising otherwise.

The degree of circularity that can be achieved strongly depends on the effectiveness and efficiency of recycling, and therefore, these need to be fundamentally quantified and maximized. Recycling does not imply only physical separation but in fact the unmixing of complex designed mixtures of functional materials, aqueous solutions, high-temperature molten solutions, mixtures of functionally connected plastics (highly difficult to unmix back to virgin materials other than through chemical methods). Any recycling process, such as a production chain, consumes resources to recover valuable materials from the EoL products. Their resource efficiencies are determined by the composition and types and quantities of resources consumed, as well as the quantities of wastes and treatable residues generated. Furthermore, the efficiency with which the desired elements, compounds or materials are recovered within that process, as well as their quality, is paramount.

Maintaining the material quality in the CE through the recycling of complex waste and EoL products requires that Beginning-of-Life (BoL) and EoL actors in the automotive supply chain are linked on a rigorous physics basis. The application of innovative physics-based recycling process simulation models provides this rigorous basis. This approach has the depth to assess and distinguish differences in product designs with respect to recycling performance and environmental impact as well as to distinguish the more resource efficient design from the others. The application of this simulation-based methodology allows that all processing options in the recycling system, ranging from disassembly and sorting to metallurgical and other final treatment processes, are understood and optimally linked in fundamental detail and can be related to product design considerations. Hence, simulation-based modeling provides a rigorous and technology-driven basis for recycling assessments, disassembly strategies and Design for Recycling (DfR) by pinpointing and quantifying critical issues in recycling related to design.

The recycling of materials, including CRMs, as contained in the electronics of modern complex consumer products plays a crucial role in the realization of a CE by keeping materials in the cycle in the same quality as in which they have originally been applied. The recycling of bulk waste is relatively easy and suits simplified CE discussions. In contrast, the challenge lies in the recycling of modern products and the complex-designed “minerals” characterized by the numerous specialty materials (metals, alloys, plastics, etc.) at their functional core.

To better understand the potential of recycling car modules, the limits and how to improve design, the EC’s TREASURE project focusses on the improvement of recovering CRMs from the electronic modules of cars. Various tangible results from this publicly funded EU Project will be discussed in detail in this paper. In this process, the selective disassembly of car electronic modules from EoL vehicles is investigated to improve recycling performance and assess product circularity from an EoL point of view. The approach applied in this work has been defined elsewhere [1,2]. The recycling assessment is based on an innovative process simulation recycling system model used to assess the recycling of car modules selected for the project by both automotive OEM partner SEAT (Volkswagen Group) [4] and partners investigating disassembly based on the rarity indicators by Ortega et al. [5] in cooperation with a car dismantling/shredding company (ILLSA [6]). The recyclability assessment has been performed to determine the recycling performance of the different disassembled car modules and their respective recycling rates within the context of a CE. This is obviously carried out to achieve a metallurgically refined material quality that can be applied as functional material in the same product. This can be achieved by the application of the best available techniques (BATs) in metallurgical recycling processing as well as to determine the best recycling flowsheet architecture to process the different car modules.

The different disassembly levels and approaches were applied in TREASURE are hence tested on optimized results from recycling and circularity (e.g., including primaries required for dilution to produce alloys from recyclates) from an End-of-Life (EoL) perspective. This information will allow us to establish general as well as specific quantification and design recommendations regarding the recyclability of the car modules. The results of the recyclability analyses will hence provide technology-based, quantified feedback to support and guide disassembly decisions and will, at the same time, provide input to define the most optimal depth of disassembly when combining recycling parameters with, e.g., the cost of disassembly. Most optimal recycling flowsheet architectures, based on the industrial best available techniques (BATs), will be advised based on the assessment as derived from the recycling simulation models.

The assessment and underlying calculations by a rigorous and physics-based process simulation model embrace the complex interlinkages of functional materials in the modules as well as all chemical transformation processes in the reactors in the system model in an intricate complete process flowsheet. This approach facilitates the rigorous evaluation of the recyclability of a product within the CE, not a simple cherry-picking of elements, disregarding all other materials; thus Product-Centric Recycling is used [1,7]. Within a Product-Centric Recycling scenario, the recycling simulation model predicts all mass flows, recoveries and losses for all metals and materials, as well as elements and compounds (both on a physical as well as chemical level). This implies that the focus goes beyond only representing Critical Raw Materials (CRMs) as elements but rather a combination of all functional materials, compounds, elements, alloys, etc., present that interact in a complex manner during chemical and physical recycling. This ultimately determines the recyclability and is crucial to quantify the CE in the EoL stage of a product. Only selecting CRMs or any other individual metal or material under consideration in an isolated manner (Material-Centric Recycling), while ignoring all other materials, elements and compounds they are associated with, will lead to erroneous results.

This paper will therefore carry out the following:

Consider numerous car modules made available for the European Union TREASURE project (note that the compositional data supplied by SEAT have been obfuscated due to confidentiality).
Apply the complete detailed composition of materials and their location on modules (parts), etc., so that these can be disassembled.
Use these as a feed composition to a system process simulation model [1] to fully understand the material and energy recovery while also being able to understand the exergy of the system.
Understand the effect of similar and different modules of various SEAT car models on their total recycling rates, as well as CRM recycling rates, including energy recovery.
Understand the effect of disassembly on improving the recycling rate.
Define DfR suggestions from this rigorous simulation-based flowsheet analysis.
Show clearly that single recycling factors are an erroneous approach and should never be followed as each product and module will have a unique Material Recycling Flower that describes the individual element recoveries and overall module recycling and energy recovery rate.
Provide a wealth of unique data on the compositional complexity of car modules and the effect of this on recycling and energy recovery.
Uniquely visualize our results, directly during product and module design, by our Recycling Labels and Material Recycling Flowers, visualizations that make the results easily accessible for designers.

The main contribution of this paper is to visualize, with an already published simulation model [1], the variations in the recyclability of different car modules. We uniquely provide a wealth of recycling rates of seven modules, which are also disassembled into smaller modules, from the full compositional data of the modules.

Furthermore, this paper also addresses the true challenge of the CE, which is linking all the actors and stakeholders in the CE system through digitalization techniques (e.g., simulation tools, process control, suitable databases that make data available to software and information technology (IT) tools, modeling, design, exergy, thermodynamics, etc.). This helps to pinpoint the physics-based innovations that will deliver the systemic performance that maximizes RE and CE [1]. This will enable the calculation of the recovery and particularly all the losses of materials from the primary and secondary (recycling) processing of minerals, Waste Electric and Electronic (WEEE), EoL vehicles (ELVs) and the EoL recycling system. This systemic simulation is fundamental to understand, assess and optimize these EoL systems in relation to design and support advisory tools. The recycling simulation models provide a rigorous and physics-based backbone for a true industry-based recycling assessment and forthcoming recycling system set up and DfR design for modularity and disassembly recommendations.

2. The Approach: Simulation-Based Recycling Assessment and DfR

Process simulation models provide a digital twin that links the various operations of the Metal Wheel within a CE as shown by Figure 1 [1]. It links mining, processing, disassembly, liberation, and sorting processing linked to the best available techniques (BATs) in metallurgical recycling processing infrastructures as depicted by the Metal Wheel in Figure 1. This includes other applicable final treatment processes such as energy recovery processing present in industries for the processing and recovery of all secondary materials and compounds.

Figure 1 depicts a computer-, thermochemistry- and particle-based process simulation tool applied to simulate the metallurgical recycling technology and system performance for the recycling of products. This specific model with 190 reactors, over 880 streams, with 310 input compounds and significantly more species (over 1000) created during the metallurgical processing has been developed by the authors [1]. It has been developed to assess the recycling of complex multi-material products to understand and capture the factors that improve design for resource and exergy efficiency within the CE paradigm. The approach followed in this paper is typically used to design complex flowsheets in industries and benefits from the extensive industrial experience of the authors of this paper. This means that physics is integrated into the simulation model to create economically viable solutions. In [1], we also develop various methods to enhance the simulation, which includes artificial intelligence, particle-based modeling and separation and similar methods. These details are not the topic of this paper.

The complete model has numerous screens that describe the interconnected processes reflected in the Metal Wheel (see Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7), based on the theory discussed in for example [2,8]. It shows the top level of the simulations of the interlinked system of technologies and activities, developed in the HSC Sim 10 software (www.metso.com) [9]. Rigorous simulation provides a thermodynamic basis for the environmental impact analysis using the Life Cycle Assessment method (LCA). Currently, the generated information flow is directly coupled to the LCA software solutions GaBi 8.0 (2022) (www.sphera.com) [10] and openLCA 2.0 (www.openlca.org) [11]. Figure 1 links the following flowsheets in a metallurgically feasible manner, and each TAB has a complete flowsheet as well, producing, in all cases, high-grade products either as precipitates or by electrorefining and electrowinning that can be reapplied in the same EoL products they originated from:

(1): The Metal Wheel, which explains the direction of feeding different scrap and EoL products into different segments as given by the numerous flowsheets that are listed below (Figure 1).
(2): The dismantling and sorting of modules into fractions of appropriate composition to direct them into the correct processing path (Figure 1).
(3): A copper recycling smelter (Figure 3), which covers smelting and copper electrorefining and electrowinning.
(4): Multi-metal smelting containing TBRC, bath smelting, and a tilting refining furnace (rectangular anode furnace) for recycling of a variety of scrap, residues and ewaste.
(5): Base metal refining, producing elements such as Ag, Bi, Cu, Pb, and Zn by fire refining and similar processes (Figure 7).
(6): Technology element refining, recovering elements such as In, Sb, Sn, Te, also As, etc.
(7): The recovery of precious metals (PMs) such as Au and Ag and platinum group metals (PGMs) such as Pt, Pd, etc.
(8): Flue dust treatment to recover elements such as Zn, Pb, Sn, Sb, Cd, In, Ge, etc., to produce high-grade products.
(9): Slag and residue processing to produce intermediate products that can be recycled back to the appropriate flowsheets for the recovery of valuable elements. The slag is of a quality that can be used in construction and is a product produced by technologies that clean the products.
(10): The solvent extraction of Co, Ni, and Cu flowsheets.
(11): The solvent extraction of Co, Ni, and Cu flowsheet II to create, e.g., battery precursor quality products.
(12): Aluminum and magnesium recycling/remelting to create specific alloys.
(13): Aluminum and magnesium alloy production to create specific alloys.
(14): An Electric Arc Furnace (EAF) for steel recycling (Figure 5).
(15): Ladle metallurgy for creating suitable steel alloys, to create specific alloys.
(16): Stainless steel recycling to create specific alloys.
(17): Pyrometallurgical battery recycling.
(18): Hydrometallurgical battery recycling creating precursor materials, also linked to other modules of the simulation model (for LiMO₂ and LFP batteries).
(19): Hydrometallurgical battery recycling creating precursor materials, also linked to other modules of the simulation model (for LiFePO₄ batteries).
(20): Energy recovery (Figure 6).
(21): LCA analysis as well as indicator calculations, aided by the direct link to LCA tools.

Each of the above is a detailed flowsheet in the 21 TABs of the model at the bottom of Figure 1. Figure 1 presents the second TAB of the simulation model. HSC Chemistry Sim 10 calculation modules utilize extensive thermochemical databases, which contain enthalpy (H), entropy (S) and heat capacity (C) data for all materials and compounds included as well as activity coefficients, allowing not only recycling rate calculations but, at the same time, an environmental analysis including an exergy assessment (Figure 4). This quantifies each stream not only in kg/h units but also in MJ/h or kW. This is rather important to also analyze the true losses in terms of the thermodynamics of all materials, i.e., in terms of exergetic dissipation or losses governed by the 2LT. In fact, this is the only correct way to fully understand the CE of products and their recyclability. This approach is especially facilitated if the data structures of the bill of materials (BoM) and full material declaration (FMD) are in a form that can easily interact with simulation tools and be transferred in a form that is normal for the simulation of primary mineral processing as well as metallurgical refining. These simulation methods, used industrially to design, simulate, and control processes, typically do not need extensive experimental input data since many of the data can be estimated using thermodynamic tools in combination with extensive industrial experience as well as a detailed understanding of operating regimes.

Furthermore, this approach facilitates the mapping of the system between (a) primary metal production, (b) a (consumer) product’s design, its product modules (parts or components), and particle definition if the product is shredded and (c) the metallurgical processing infrastructure, which can be very similar to primary metallurgical processing. While many factors affect the degree to which materials are liberated, the ease of dismantling a product, e.g., easily detachable connections and a lack of gluing and other inconvertible connection types, is crucial to improve the accessibility of components, their repairability, and ultimately, their recyclability and/or reuse. The idea has been applied in the form of recyclability indices by Van Schaik and Reuter [1], which, as presented by, e.g., iFixit [12] and Greenpeace [13], can be used to categorize and define different scenarios for product design assessments. However, predicting mathematically in which stream complex particles statistically will end up in is complex. A significant research effort is being devoted to this aspect of system simulation to be able to deal with particles and their chemical properties to understand their ultimate metallurgical recovery during refining in the appropriate flowsheets [1]. The simulation models can also predict the recovery of CRMs and other technology elements within these intricate flowsheets, of which a few are shown further below in this paper. This detail provided by a product-centric simulation- based approach therefore goes significantly beyond the material flow analysis (MFA) methods [14] used during the material-centric analysis of steel, Al alloys, and waste streams, for example. MFA, at least currently, does not provide the thermochemistry of each stream, nor the excess thermodynamic properties of entropy and heats of solution. MFA cannot estimate the true efficiency of systems fundamentally, whereas simulations based on thermochemistry can.

In summary, the approach tested and visualized for the recycling of car parts provides a fundamentally based framework for economically viable decision making [15]. This quantifies the true opportunities and, above all, the limits of the CE.

Figure 1. The second TAB of 21 (see bottom of figure for all TAB names) of a complete process simulation model for the recycling of complex consumer products. The TABs show all the involved technologies to realize the CE recycling of, e.g., mobile phones, WEEE goods, laptops, LED lamps, and car electronics. The robotic separation and disassembly are shown. In total, the model includes 190 main metallurgical reactors, over 310 materials (i.e., compounds, plastics, alloys, elements, etc., in feeds), >1000 species in the various streams created by the metallurgy, and 880 streams [1]. Please see [1] for explanation of the metal wheel and the coloring.

2.1. The Nexus of Processes Simulation and CE—Using Thermodynamics for Maintaining Quality of Materials and Energy Flows into and out of a Product

Circularity indicators should permit the fundamental identification and minimization of residues and losses and ultimately therefore be able to quantify and minimize the creation of entropy across the complete value chains of the CE. The indicators should thus be able to advise on how to economically close material loops through EoL recycling. Digitalization platforms have evolved significantly to estimate the bulk, minor elements, technology elements, metal, alloys, and material flows in addition to the exergy and energy flows of the complete CE system with its various stakeholders [1,15]. The simulation-based approach provides the solution missing in the usual analysis of the CE, emphasized by Lazarevic and Valve [16]. This highlights that high-profile publications circulated to European policymakers emphasize closed loops but largely ignore the demonstrated losses over the lifetime of metals [17]. Furthermore, Reuter et al. [18] provides a critical discussion of a CE, arguing that a CE is sold as an environmental messiah, a stimulator of the economy, and a creator of jobs by its promoters, of which the Ellen MacArthur Foundation (EMF) is the most influential [19], forgetting to mention the second law of thermodynamic (2LT) losses. This is pitched despite 2LT losses as and “expectation that an economy-wide perfect circle of perpetual fully closed material loops can be a material reality” as highlighted by Lazarevic and Valve [16]. As Goldberg [20] notes, the fates of toxic chemicals such as Pb and Hg are also ignored, not to speak of their chemical composition and manifestations. Thermodynamic thinking is not mentioned at all in the previously mentioned superficial discussions. Moreover, some prominent global business consulting firms claim that full circularity and industrial and economic utopia can be achieved by simply using “only inputs that can be continuously reused, reprocessed, or renewed for productive use (e.g., renewable energy, biomaterial or fully recycled/recyclable resources)” [21]. Statements like this demonstrate a lack of understanding of the complexities of bringing EoL goods back into utilization or of recovering secondary resources from them. The ever-present 2LT dictates that continuous reuse, reprocessing, renewal, and loss-less recycling cannot be achieved due to the degradation of the quality of energy (and thus materials). Losses and residues can be reduced but cannot be eliminated. The apparent closure of one loop might be at the expense of another; the closure of a material loop relies on the opening of an energy loop elsewhere because of the inevitable dissipation of exergy [1,22].

While products can be fully manufactured from recycled materials, losses will occur in recovering those manufacturing materials from recyclates elsewhere. This is conveniently not mentioned by OEMs, i.e., the emissions created during the recycling of often non-related products. As emphasized, products can never be fully recycled because of unrecoverable losses as dictated by the 2LT. To ignore this principle would be to hinder impactful innovation—true RE can be determined only if losses are considered— and thus, CE gurus then could claim that a great cup of coffee could be produced with its many notes of aromas from yesterday’s stale cup of coffee. Waste cannot be designed out of a system if its existence is ignored. Clift [23] rightly states, “It’s time to speak up for thermodynamics. The future of our planet depends on it”. Only by taking into consideration the effects of the 2LT can the limits and true potential of CE systems be assessed. In addition to the 2LT, population growth and the inevitable associated increased consumption cannot be ignored. As highlighted by Beylot et al. [24], one needs to consider the mass and energy balances in an LCA seriously as this is the basis for accounting for the dissipation from a product system. The approach in this paper shows the state of the art on how to determine the recyclability of automotive modules.

2.2. KPIs and Information from Simulation Models

The recyclability simulation models provide the following KPIs and results for every unique EoL module used in this paper for various car modules:

Recycling and recovery for complete modules or a product, as well as for individual elements and materials:
○
Total recycling rate (%) visualized by the recycling index (see Figure 2a) of a car module (%).
○
An individual material recycling rate of all materials/elements/compounds included in the car module (e.g., Fe, Cu, Au, Ag, CRM recycling rates, etc.) in % (also available in mass)—visualized by the Material Recycling Flower (%) (see Figure 2b).
○
Energy recovery in MWh/t of feed or per car module.
Recommendations on the most optimal recycling flowsheet architecture or routes (based on the best available technologies at the industrial level)—this will differ per car module and disassembly level.
Feedback/advisory to dismantlers on additional disassembly or the effect thereof to optimize recycling.
Feedback to eco-designers based on metallurgical incompatibilities (qualitative from the Metal Wheel) and quantitatively based on the findings of the recycling simulations and detailed quantitative insights into the recoveries and losses of materials/elements/compounds of these car modules to perform DfR.

A simulation-based Recycling Label (Figure 2a) and Material Recycling Flower (Figure 2b) have been developed to visually show the true material recycling back into the same product [1]. Figure 2a shows the overall mass-based recovery of materials in increments of 10mass% of a module/part, while Figure 2b shows (in increments of 10mass%) the recovery of materials to high-quality products in terms of elements, with reference to total element input. The red in Figure 2 indicates 0-10% total mass and element recovery, while dark green indicates 90-100%. A similar label can be defined that shows the dissipation of exergy and therefore exergetic performance, but this is not the topic of this paper. The 2LT states that recycling rates must be less than 100%, additionally quantifying the loss of quality of materials. This is driven by the dilution and dissipation of materials, which is ultimately reflected by the economic performance of the system.

The advantage of process simulation is the relative ease with which input and operating parameters can be changed to investigate their effects on the resource consumption and efficiency of processes over complete life cycle systems. Comprehensive parameter studies enable the optimization of a system for sustainability as well as providing the details necessary to understand and interpret the recyclability results for the different indicators. This visualizes and stimulates an understanding of how these indicators change with modifications within the CE system. As an example, the purity of a recovered material usually decreases as the quantity recovered increases, which is the classical grade–recovery relationship [1]. Changes in the system (e.g., different feed material compositions, the use of different technologies, or different product specifications) due to this relationship can be evaluated using the indicators described below to estimate the balance between maximum circularity and environmental sustainability. The simulation model provides feedback and advisory to different stakeholders in the value chain of automotive electronics (ranging from production to recycling) on the effect of design and/or redesign. This is carried out in a visual manner as depicted by Figure 2. These figures will be used to provide the results in a unique manner, visualizing the effect of various processing options.

Figure 2. Recycling Label (a) depicting the total recycling of materials back into the same product, calculated by a model such as the one depicted in Figure 1 and (b) Material Recycling Flower depicting individual material recycling rates [1]. This approach was used, for example, to calculate the true recycling percentage of the complete Fairphones 2 and 3 and thence contributed to the improved modular design of the Fairphone to maximize recycling. Refer to this figure for details of the smaller versions below in the results.

2.3. Design for Recycling and Design for Circularity

The functionality of products dictates that materials are designed and combined to interact in a complex functional manner to deliver a desired functionality. It is self-evident that this complexity in products will inevitably create very complex waste streams [1]. Therefore, recovering materials from these complex products requires a deep understanding of the physics of separation both in physical and chemical terms of materials into high-grade materials within a complete system. This is what the Metal Wheel reflects [1]. Thus, in the context of this paper, true Design for Recycling (DfR) must incorporate complex physical and chemical separation physics into the design tool. As mentioned previously, this detailed simulation will reveal and quantify the inevitable losses created by the complex functional connections in products. It must also be noted that DfR may make no sense at all since the contained material and metal value is so low and their connections so intimate due to their functionality that the poor economics of this process makes recycling and recovery impossible. This is driven by the 2LT. No Design for Recycling principle will help in these cases. This highlights that product design and recycling systems (both physical and chemical) must be harmonized for optimal resource recovery and resource efficiency. This suggests that design for resource efficiency should be the driver for creating a recycling processing system in the CE that uses the best available technology (BAT) and, above all, is certified to meet this requirement in a CE paradigm. This demands that a recycling advisory must also be directed towards designing the most optimal recycling and CE system set up. Thus, the focus must most certainly also be on the criticality of the processing infrastructure within the CE. This means that disassembly must be harmonized with shredding, sorting (and other physical separation techniques) and the most suitable (metallurgical) recycling infrastructures. This will optimize the CE performance and resource efficiency of the product recycling system, the simulation models, and the use of the Metal Wheel [1] to link product design to the complete recycling system. Fairphone [25] demonstrates the application of rigorous system modeling for a recycling assessment and Design for Recycling of Fairphones 2 and 3. As for Fairphone, the recycling of a product within the CE implies creating the same material quality after recycling so that it can be applied in the same product. This definition is at the basis of the analysis as the objective is to create as many economically viable material products of the required functional quality as possible. Therefore, three levels of CE have been defined to assess recycling; energy recovery is the fourth option:

Closed-loop CE: recycling into high-quality products with material properties equal to the original product/material.
Open-loop CE to be processed into a closed-loop CE: Recycling into intermediate products, such as low-grade alloys, calcine, etc., which require further physical sorting and/or chemical upgrading to achieve the required high-quality material properties/alloy quality to render a closed-loop CE. At the same time, open-loop CE products suitable for repurposing could also be produced as a product from sorting/upgrading the intermediate products to render a closed-loop CE. The possibilities of the processing of open-loop intermediate products into closed-loop CE products is subject to economic, thermodynamic, and environmental constraints.
Open-loop CE—recycling into (intermediate) products such as slag and flue dust for repurposing: the production of building and construction materials, etc., requires significant energy and thus exergy dissipation and thence costs to convert them into level 1 closed-loop CE materials.
Energy recovery: If plastic and organic material functional combinations are too complex, they will be used (i) in some of the processing routes as an energy carrier from which the energy content is (partially) recovered (in the Cu-processing route, organics are also used as reductant materials), or (ii) as a source of energy. This is important as many plastics and organic materials are intimately functionally linked. Thus, to physically recycle these is exergetically and thus economically speaking a true challenge.

The three different levels of closed- and open-loop CEs in recycling correspond to the three outer circles in the Metal Wheel in Figure 1 [1], with the closed-loop CE in the most inner circle (after the dark blue base metal circle) and the open-loop CE as reflected by the most outer circle. Energy recovery and flow drive the Metal Wheel.

2.4. Simulation-Based LCA

An LCA is in general used as a method for the systematic assessment of the environmental aspects and impacts of product systems. This considers the life cycle from raw material acquisition to final disposal. Process simulation can contribute to the goal and scope definition phase of an LCA and is linked to LCA tools as discussed in detail in the Handbook of Recycling [1,15]. The life cycle inventory analysis is often performed using background data from commercial or public LCA databases (Sonnemann and Vigon [26]). While these contain useful inventory data for many processes, the datasets do not always fully or even often incorrectly represent the processes being evaluated. For example, some processes and technologies are outdated, some are not sufficiently geography-specific, and datasets for emerging and new technologies are often not at all available. New processes are obviously not present at all. Process simulation can enhance the inventory analysis stage by generating up-to-date mass and energy balances that can be transferred to the LCA, with more detail on the elements and compounds present in each stream of the process [1].

Figure 3. The first steps of the “Cu processing route”—oxidative smelter (Cu Isasmelt™), reduction of Pb bullion (Pb Isasmelt™ Reductive smelter) and Cu refining. The Isasmelt™ reactor (a Top Submerged Lance (TSL) reactor) can also be a proxy for a TBRC (Top Blown Rotary Convertor)-type reactor, and the metallurgy is determined among other factors by the partial oxygen pressure and temperature within the reactor as well as mixing and flow. Also shown is the oxidative leach of raw copper and the subsequent electrowinning of the copper, which is then linked to other TABs in the complete flowsheet. Flows in t/h.

Figure 4. Screen capture of recycling model typical input definition in HSC Sim, showing illustrative car module compositional input integrated in HSC Sim (left column). This figure also reveals all other parameters (next to mass % of input) such as flow rates (kg/h) and energy thermodynamic parameters (in kW). The input to the model has been simulated for 20 ton/h to render the process industrially relevant. Also shown are the physical and chemical as well as total exergy contents of each component and total module. This is the same data structure and detail as for each of the 880 streams in the process simulation model, attesting to the simulation model’s realism. (Note: * is used to define specific chemical formulae for specific compounds as these have very specific enthalpies and entropies, the # instances indicate that there is no density data available in the database for those substances, thus division by 0).

Figure 5. Steel scrap smelting to create a dirty iron-rich alloy from steel-rich fractions from the module. This is used as there is sufficient Fe in the module as a major alloying element. Dissolved PGMs could make the processing of alloys profitable but creates significant residues during hydrometallurgical processing (Goethite). However, this is not likely a preferred route due to stringent alloy compositional constraints dictated by alloy type. Therefore, these fractions can also be processed in the nonferrous flowsheets.

Figure 6. Energy recovery processing to create calcine (oxidized elements) as well as some highly alloyed metals and low-value metal alloys. Primarily, however, energy from all car modules robustly processes the many complex and mixed plastics/organic materials in the modules. This route is followed if plastics cannot be separated into a material form with sufficient purity, which is the case in complex modules. Can also be pyrolyzed i.e. in more reductive mode to create another suite of products, offgas composition and flue dust.

Figure 7. Detailed flowsheet of processes required for recovery of all recoverable (technology) elements (green bullets in the Cu segment of the Metal Wheel), in this case, the recovery of Ag, Bi, Cu, Pb, and Zn among others in this specific TAB of the complete flowsheet’s 21 TABS.

The product-centric approach to recycling [1,7] provides the platform for assessing and optimizing the recovery of all materials and energy from designer “minerals” such as cars, car electronics and WEEE. In the United Nations Environmental Programme (UNEP) Metal Recycling report [7], it is stated that resource-efficient recycling requires a robust, interconnected high-tech metallurgical infrastructure as a crucial enabler of the CE paradigm. In this document, it is shown that a mineral- or a product-centric simulation-based understanding is required. This approach contradicts the more limited and simplistic material-centric approach by Reck and Graedel [27] and Wagner et al. [28]. Ideally, it is necessary to harmonize these approaches, recognizing that the material (metal)-centric approach is an oversimplification of the mineral (and product)-centric approach as this cannot be applied to assess, quantify, and optimize recycling and material flows from complex multi-material products and interlinked metallurgical processing systems.

In summary, a process simulation’s main contribution would be in the life cycle inventory stage, with the added advantage that thermochemistry with all its theoretical detail is the basis of the analysis. Therefore, detailed mass and energy balances are a useful data source for an LCA to quantify losses and the resulting potential environmental impacts, as well as other analytical methods.

3. The Data: Data Processing of Car Module Data and Transforming to Compatibility for Simulation

A successful simulation-based recycling analysis requires detailed product data of the product or car modules and their structural build-up. This implies that the complete “mineralogy” of a product must be available, which is the usual input basis when simulating and optimizing metallurgical processes and flowsheets [1]. By analogy, the meaningfully analysis of the recyclability of products can only be optimized with an in-depth understanding of metal and material distributions through the (recycling) system, which in turn depends on the availability of relevant physical, metallurgical, and thermodynamic data and knowledge. This differs fundamentally from the superficial data collection depth and detail as discussed by Wagner et al. [28], in which only an element-based approach is used for data collection and inventory, based on a material-centric point of view. This is not detailed enough for a CE assessment.

Scheme 1 gives an overview (obtained from the EU TREASURE project [29]) of the different car modules selected for disassembly. This reveals the focus on metals, which is applied in the thermodynamic rarity assessment as applied in this project by Ortega et al. [5]. The successful accomplishment of recycling as well as environmental and exergetic assessments requires that the full “mineralogy”, i.e., the full chemical composition of all metals, materials, and compounds (implying metals, metal oxides, organics, inorganics, etc.) must be available and applied during analyses. Without this depth of data, a recycling and linked EoL exergetic assessment is not realistic, nor will it produce reliable results. The data as presented in Scheme 1 are hence processed in this paper to considerably more detailed compositional detail. This detail is described in this section.

The selected car modules belong to SEAT models Ibiza and Leon and correspond to the most critical ones according to the assessment carried out within the TREASURE project. SEAT Ibiza and SEAT Leon models are chosen, given that they are the most representative models in terms of sales of the SEAT brand. From 2005 to 2019, more than 2 million cars of these models were sold worldwide. In addition, both models, Ibiza and Leon, are hatchback compact cars, based on Volkswagen (VW) Group platforms. Therefore, most of the contained car modules are shared among many vehicles from the Volkswagen Group. That is, Ibiza is on the VW Group’s platform that is now shared with VW Polo, Audi A1, and Skôda Fabia, whereas Leon is on the VW Group’s platform shared with VW Golf, Audi A3, and Skôda Octavia [29].

Overall, such vehicles represent different generations of cars covering as many different car modules and configurations as possible. Further, the high-trimmed version was selected due to its higher proportion of electronic car modules. In addition, considering that more than 2 million cars have been sold in recent years, it becomes clear that a sufficient volume of such cars will be arriving at authorized treatment centers [6].

Scheme 1. Overview of car modules selected for disassembly (figure from TREASURE) and general approach to data specification, which reveals the focus on just the CRMs/metals contained in the different car modules in view of the determination of rarity%.

3.1. Data Analyses and Processing

Data on the composition of the car modules identified for disassembly were made available in the format of MISS data files and was provided by SEAT [4] within TREASURE [29]. The MISS data files were set up to comply with ELV directive requirements. Hence, although the data in the MISS files are provided in a relatively well-structured and detailed format, the MISS files require extensive data analyses, processing, structuring and completion to prepare and structure them in a consistent and detailed format, from which the input to the recycling simulation models can be defined, i.e., they must be available in a form that a thermochemically based simulator can recognize to provide the relevant thermochemical information (see the various figures and tables below). The material information is mainly only detailed for the metals, and their structure and consistency require improvement. This means the full compositional information of all materials must be made available from the MISS data files, as well as their distribution over the sub-modules, to provide input to the recycling process simulation models to calculate the recycling performance of high-quality products.

The data provided by SEAT [29] are analyzed for completeness, consistency, unclarities and possible errors and processed by the authors to define the input data for the recycling assessment per car module. This involves the following activities, as applied in this paper:

The identification of data inconsistencies or errors, which need to be corrected when present (e.g., mass balance inconsistencies, missing material/compound data, etc.—also see below).
Gaps in the data (gaps) must be completed where required and if possible (e.g., missing material and compound data, chemical formulas, Chemical Abstracts Service (CAS) numbers, etc.).
Mass and compositional data must be verified, completed, and calculated.
Data must be defined in terms of the complete composition of the product or module and sub-modules, thus extending to all compounds, functional materials, alloys, plastics, etc., and their spatial position on the car modules and sub-modules (for example, aluminum, Al, or an alloy of aluminum, Al₂O₃, as an oxidized/anodized layer on the aluminum, a filler, etc.).
All data must be transferred from material descriptions, names and/or CAS numbers to stoichiometric chemical formulas that are recognizable by a thermochemically based flowsheet simulator, which is carried out based on a very extensive consultation of material and compositional databases.
The data description of organic compounds needs to be carried out, which are in general only provided in a descriptive manner in the MISS data, and they are added to the data file in terms of CAS numbers and stoichiometric formulas/composition (this is important as this determines the enthalpy and entropy of the compounds).
Product data are transformed from a mainly metal- and element-based approach for a full compositional analysis.
Supporting the data processing and improvement, a database is required containing material compositions and chemical/molecular formulas to ease upcoming data analyses on other modules.
Masses for all materials and compounds related to their distribution in the module need to be calculated.
A full mass and compositional analysis in terms of chemical formulas must be defined and derived for each of the different car modules and sub-modules as listed in the MISS. Excluded are confidential material and compound data.
A consistent and detailed data structure must be defined, representing all compounds regarding their chemical/stoichiometric formula and corresponding masses and distribution over the car module as required for the recycling assessment.

This data detail goes far beyond what is often simplistically presented in the academic literature [30], necessitating the abundant definitions of circularity and circular economy [31]. The many definitions can be attributed to the lack of a fundamental basis. Rammelt and Crisp [32] point out so clearly how important it is to consider the exergy aspect of the CE system. The simulation-based approach provided here makes it possible to calculate the exergetic efficiency of a complete system. It is clear from the results that this is rather low and then affects the economics of the CE. This goes far beyond the superficial frameworks as discussed, for example, by Lieder and Rashid [33], which is one of many that neglect to integrate physics into the system structure.

3.2. Car Modules Included in the Recyclability Assessment

Scheme 1 gives an overview of the car modules applied for the disassembly and recycling assessment. Within TREASURE, a selection of car modules was made for the Leon II and Leon III models, also carried out to be able to compare the difference in the recycling behavior of the subsequent versions of these models. Furthermore, further disassembly of the different car modules was explored and analyzed by other partners in TREASURE [29]. To assess the effect of additional disassembly on recycling performance, level 2 disassembly was also included in the recycling assessment. This was carried out for one of the car modules, i.e., the Combi-instrument of Leon II. These analyses provide a demonstration of how a recycling assessment and disassembly analysis can be linked and allows an assessment of the effect that additional disassembly has on the recycling performance of the car module. Combining the results of the recycling analyses for level 2 with costs for additional disassembly (provided from disassembly analyses) will allow us to determine the trade-off between disassembly costs for improved disassembly and increased recycling performance consequently. This will allow us to define the most optimal balance between disassembly depth, recycling performance and costs. The following seven car modules with indicated disassembly levels are assessed in terms of recyclability and circularity:

Infotainment unit—Leon II (level 1 disassembly);
Infotainment unit—Leon III (level 1 disassembly);
Combi-instrument—Leon II (level 1 and level 2 disassembly);
Combi-instrument—Leon III (level 1 disassembly);
Combi-instrument—Ibiza IV (level 1 disassembly);
Additional Brake Light—Leon II (level 1 disassembly);
Additional Brake Light—Leon III (level 1 disassembly).

3.3. Results of Data Analyses and Processing

Scheme 2 gives an impression of the data of a typical Material Information Systems (MISS) file. Only a small section is given as, for some car modules, the data file contains over 2300 rows. Also, the confidentiality of the data needs to be adhered to. These data are subsequently transformed into a form that is recognized by a thermochemistry-based process simulator.

Scheme 2. Snapshot/screen caption of exemplary data format in MISS file (left side) and data derived through data processing in red box (right side), which is the information entered into the HSC Sim simulation model. This MISS file is compliant with the EU EoL car directive.

3.3.1. Classification of Organic Compounds

The car modules included in the recycling assessment contain more than 320 different compounds (metals, alloys, oxides, sulfides, inorganics, organics, etc.), of which around 220 compounds are organic materials. All compounds are defined and included in the process simulation platform. To make the processing of the data more efficient and avoid over-detailing when this is not of value, the organic materials are organized into different categories to reduce the number of different organic compounds to be included into the model and platform. Thus, organic materials were classified into different groups/classes based on their main compositional components (e.g., the presence of Br, Cl, Si, F, etc.) and their ratio of C, H and O. Organics can either be present as plastics or as organic compounds within the different structures of the car module. Not to be forgotten are the fillers and coatings in and on plastics. Plastics are often functionally linked to other materials (e.g., containing fillers, coatings, etc.), complicating their separation and classification. Therefore, organic compounds are classified into 65 classes, covering the composition of the organic compounds present, including the various additives and fillers. In total, 181 different compounds, elements, and materials are included in the model.

It is crucial to be aware that the process of data classification can only be performed the moment the full compositional detail of all organic compounds is known from the extensive data analyses and processing has been performed on the MISS data files. Without insight into the full range of organics present including the applied additives, fillers, etc., a classification is not possible and would lead to baseless and erroneous decisions, which would render the recycling assessment and related exergy/environmental assessment unreliable.

Adding additives to plastics often limits their material recycling as this lowers the quality of the final recycled material produced from the recyclate. It often makes no sense to recycle such complex mixtures of functional linked plastics into quality materials again. Therefore, recycling into high-grade materials is challenging. Thus, the use of organic materials in the smelting process(es) both as reductant materials as well as energy carriers in the process is the usual industrial practice to achieve the required thermodynamic and operation conditions for processing and maximal material and energy recovery. Having said this, it can make sense for a plastic-rich or purely plastic module, in which the plastic can easily be fully separated from other materials, to be reused.

3.3.2. Full Compositional Build-Up of the Car Modules—Results of the Data Processing

The data processing results in a full compositional analysis for the different car modules. To be able to compare the composition of the different car modules, as well as to structure the input to HSC Sim recycling simulation models and to smooth the integration of these data into HSC Sim, for each car module, an identical list of materials/elements/compounds is defined. This list of compounds is defined based on the full composition of all different car modules, as well as including all compounds and phases that are created in the recycling processing of these car modules in the different processing routes as included in the model. Table 1 shows exemplary data about what the input composition derived from the MISS data file after data processing and completion looks like. It shows that all materials are defined based on their full chemical composition and corresponding mass in the car module, adding up to 100%. This mass distribution is defined from all individual masses of each of the compounds in each module/sub-module and component of the car module. These data are available for all assessed car modules in this format.

The composition as defined in Table 1 is provided for a section of the complete composition/table in view of the confidentiality of the car module compositional data. Car module compositional data are derived based on the data processing for all car modules and sub-modules assessed. This full compositional data is, however, not provided in this paper due to data confidentiality. To be able to obtain an overview of the compositional similarities and differences for the different car modules and reveal the link to the compositional requirements and suitability of the various (metallurgical) recycling processing infrastructures as assessed, the composition of all car modules is given in this paper in a classified obfuscated form in various pie charts. However, it is important to be aware that to assess compatibility with the processing routes and assess recyclability, the full compositional detail of the input, of which a section is illustrated in Table 1, is required and included in this work.

This data processing provides the input data in a format suitable for recycling and recovery rate calculations using a process simulation platform. Figure 4 shows a screenshot of the HSC simulation model and how these data are integrated into the recycling simulation model in the data structure of the thermodynamic process simulator. For the case in which disassembly level 2 is included in the assessment, the different modules are grouped/indicated in the MISS file. The compositional data are then grouped with their corresponding composition for each of the different disassembled sub-modules, resulting in a similar table as presented by Table 1, listing the compounds and masses for each individual sub-module (e.g., PCB modules, plastic-containing modules, ferrous modules, etc.).

Table 1. Input definition of car module derived through data processing from MISS data file—full compositional input to HSC Sim recycling simulation model (after the classification of organics) for an exemplary automotive module (only a selection of the complete composition is shown in view of confidentiality, the many decimals kept showing data were calculated from real modules).

Module X
Compounds (Chemical Formulas)	Mass % in Car Module	Compounds (Chemical Formulas)	Mass % in Car Module
INORGANIC MATERIALS (illustrative selection of the 310)		Si	0.038089945
2CoOTiO₂
Ag	0.050879254
Al	3.324194317
Al(OH)₃	0.000221513
Al₂O₃	0.010980374	SiO₂	6.120841659
Al₂O₃*2SiO₂	0.000735423	Sn	0.330726024
		SnO₂
As	6.25873 × 10⁻⁵	SrFe₁₂O₁₉	0.369481684
As(CH₃)₃	0.000389997	Sr	0.002444903
Au	0.003174198	Ta	0.034698979
B	0.011693839	Tb
B(OH)₃		Te
B₂O₃	0.000159093	Ti	0.000190354
Ba	0.026569005	TiO₂	0.05595244
BaO	0.004543896	Ti(OC₃H₇)₄(TTIPg)	0.003168093
BaSO4	0.006158511	V	0.000866525
BaTiO₃		W
Be	7.60241 × 10⁻⁶	Zn	0.273005216
Bi	0.001581435	Zn(OH)₂	7.19722 × 10⁻⁶
Bi₂O₃	7.22426 × 10⁻⁶	Zn₅(OH)₆(CO₃)₂
C	0.079298357
CaCO₃		ZnO	0.000238977
CaMg(CO₃)₂		ZnSO₄
CaHPO₄*2H₂O	5.2456 × 10⁻⁵	ZrO₂
…	…	ORGANIC MATERIALS (only selection of ca. 200)
Pb	0.147341834	C₆H₁₂O₆(ADG)	3.332776712
PbO	0.000165707	C₆H₁₈OSi₂(HMDl)	0.08860842
PbO*TiO₂	0.000809446	C₆H₄O₂(QUIg)	0.307403945
PbO*ZrO₂	0.000668399	C₆H₅F(FBZg)
PbSiO₃		C₆H₆S(BTHg)	0.158417758
…	…	…	…
Pd	0.002698819	C₇H₄F₃NO₂(3NIBg)	0.014802409
Pt	1.92979 × 10⁻⁵
Ru	9.73492 × 10⁻⁵	C₇H₆O₂(BAC)
RuO₂	1.07967 × 10⁻⁵	C₈H₁₈O₂S(DBSg)	0.00169436
S	0.01450747
Sb	0.002978447		0.000222076
Sb₂O₃	0.008691691	C₈H₈(COTl)	0.00615385
Sb₂O₅	3.36309 × 10⁻⁵	The above is a short illustrative list of many organic materials
Se		SUM	100.0

3.4. Automation of Data Processing for TREASURE Platform and Digitalization for CE Assessment

The processing, completion and structuring of the data are extremely time-consuming as, at the moment, these processes can only be carried out manually. In view of the development of the TREASURE Circularity Web Platform and Advisory tool, a web-based platform was developed as a new information-sharing tool among all stakeholders in the automotive value chain, and for the integration of the results of the recycling assessment into this platform, the automation of data processing needs to be module of this process. In general, the digitalization of data is a crucial aspect of a CE assessment. Automation is required in the platform and for the digitalization of a CE, facilitating a smooth data conversion between OEM data (MISS or other product compositional data files) and recycling rate predictions. Based on the performed data processing as discussed and performed in this and previous work (see also [25]), the data structure and points of attention for the automation of data processing can be defined. This provides input to future developments and activities to be performed in this and similar projects and industries for the CE and sustainability assessment on data processing and integration within the TREASURE platform and the required format of the data lakes provided and applied within this and other types of digital platforms and tools. This allows us to give feedback to the OEMs in terms of the improvement of data definition, detail and set up of the MISS data files to facilitate the automation of data processing. Some points which should be accounted for in view of the automation of the data are suggested below:

Data should be provided, for example, in an xlsx or comparable format (not as a pdf as is presently often the case).
All material data/descriptions (now defined under names in the MISS data files) should be defined in a clear manner, which leaves no room for uncertainty (e.g., abbreviations should be written in full), and for all material names, the corresponding CAS numbers should be included in the MISS file/product data file as this would allow for an easy lookup of stoichiometric/chemical formulas.
A database containing all CAS numbers of applied materials/substances in the car modules and their corresponding full chemical/stoichiometric formulas should be clearly defined.
All masses/weight percentages should be given in a point-separated format (for decimal definition).
Masses of individual materials/modules should add up to the full mass of components/100% (this is not always the case in current data files), and the same applies for all masses within the sub-modules or components.
The structure of the data file (masses and weight percentages) should be defined in such manner that an easy calculation of mass per material, compound and substance is possible in an automated manner from the data file—this demands a thoroughly thought-through set up of the data file.
The number of times a module occurs in the car (defined under “Menge”, German for the amount) should be defined in an equal manner for all sub-modules. This is required for a proper calculation of the mass per compound within a sub-module or component.

The required structure and detail of the data format are given in Table 1. Details on manual data processing to be transferred into automated data processing are available from the data processing as performed within TREASURE. This approach to data collection and data processing and the required detail of data has also been adopted in the CWA CEN Workshop Agreement “A methodology to improve the recyclability rate of Strategic/Critical Metals from car electronics” as prepared between the different partners in TREASURE (CWA, [34]).

4. Recyclability Assessment and Data for Modules

The recycling of the various disassembled car modules as defined in TREASURE is assessed by the application of an innovative recycling flowsheet simulation model as described above. This section will describe the further development and set up of the recycling system flowsheet simulation model, which has evolved from past work to include the considerable number of materials in the modules. It is important to keep in mind that recycling in the context of the CE is understood to produce the same quality of materials so that they can function at the same quality in the same product again. The recycling rates of a product and its composing materials and compounds are determined by the following:

The design, structure, materials, and compounds used in a product, or module.
Their functional connections and the full composition of each (multi-)material.
The recycling route(s) and combination of processes, which are applied to recycle the complete product and/or different modules or modules.

Previous research by the authors on the recycling of complex EoL products such as mobile phones [25] made very clear that a modular, physics knowledge-based recycling approach results in a better recyclability of materials and compounds. Modularity allows for a better “separation”, i.e., by the (automated or manual) dismantling and selection of recyclates and modules (or parts) for subsequent focused metallurgical and other final treatment processing. This approach is followed in this paper.

The recycling flowsheet simulation model is applied to assess and calculate the recycling/recovery rate of the car modules and sub-modules for the level 2 disassembly assessment. These flowsheets, of which Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7 is a selection, are industrially realistic and economically viable for different processing routes. The car module compositional and structural data are used as input, as derived from the MISS data as obtained from SEAT. Subsequently, recycling/recovery rates are calculated, and different recycling processing options are evaluated, including the energy flows within the recycling system. The results provide recycling KPIs, disassembly recommendations and a BAT flowsheet architecture for the recycling of each of the modules.

4.1. Recycling Process Simulation Model

The processing flowsheet was evolved from [1] and was extensively updated and expanded within TREASURE, investigating and including the best suitable technologies for the processing of the selected car modules for disassembly and adopting and processing all of the numerous materials, compounds, and elements, etc., present in the car modules. Each flowsheet in each TAB is connected appropriately with other flowsheets in the other TABS. The flowsheets therefore cover the complete metallurgical (and other final treatment) recycling processing infrastructures as listed previously in Section 2, following a product-centric approach [2,7].

Materials of special interest (e.g., CRMs) are given special focus where required, e.g., when selecting the most optimal or most suitable recycling route(s) for processing the different disassembled car modules or additionally selected modules for the further disassembly of the car modules. The thermochemistry-based flowsheet simulation model is partially depicted by Figure 1, Figure 4, Figure 5, Figure 6 and Figure 7, noting that there are plenty more flowsheets in the non-depicted TABs, connecting 190 unit operations.

4.2. Recycling Assessment of Car Modules and Selection of Most Suitable Processing Routes

Figure 1 depicts the basic metallurgical infrastructure in the center band that makes the recovery of elements in each segment of the Metal Wheel possible due to the refining and alloying infrastructure and compatible chemistry and material physics [1]. The Metal Wheel describes the simulation models by the complete flowsheets and range of reactors composing the different (metallurgical) processing infrastructures (as displayed in the “Feeds” sheet of Figure 1). On this basis, the effect of the different recycling processing routes on recyclability can be determined, and the most optimal and suitable recycling processing flowsheet for the module under consideration can be determined. To render the simulations viable and realistic, the selection of the most suitable range of metal and plastic processing routes (from the entire range of infrastructures available to process the different car modules) is based on the expert industrial knowledge of the authors. The most suitable routes imply a recycling processing infrastructure in which the compounds of the module are most optimally recycled with a minimum of inevitable losses and emissions. This will differ per module due to its specific material composition as defined in the design. For some modules, different options in processing might be considered, depending on which of the materials is preferred to be recycled from the car module’s material content.

All technologies included in the recycling assessment are industrial operations running at an economy of scale. In the simulations, only the selected car modules under consideration are assessed in terms of their recyclability and are fed as the only secondary input to the simulations. In normal operation conditions, different input types will be mixed and integrated on site by the operator to create the most optimal input to the furnace. This provides the economy of scale to also feed different car module types (as part of the other input flows) to these industrial plants. In the simulations, the effects of only simulating the recycling performance of the car module are included in the setting of the processing conditions and input to address the normal operation conditions and input integration. For example, due to the low copper grade in (most of) the car modules, the copper routes require additional heat to heat slag for a specific operating point, i.e., these modules are processed on a backbone of copper metallurgy. Usually, the processing of these modules is integrated and mixed with other copper and valuable materials and processed together to render the processing economic. Moreover, 20 t/h is the feed basis of the HSC Sim simulation of the recycling assessment for all car modules and processing routes. This allows us to simulate normal operating conditions while still being able to address the specific recycling rate, losses, and emissions of the car module under consideration.

In the recycling assessment as discussed in this paper, it is included that all fractions/modules lie within the acceptable ranges of the selected processing route/plant and all materials are taken care of technologically as well as economically in the selected and/or most suitable processing route(s). This implies that the car modules are acceptable within the range of integration and mixing with other (primary and/or secondary) metal sources as is normal practice in the metallurgical plants included in the recycling simulation models. It will be discussed per case if or where problems can occur due to the composition of the modules. Hence, where needed, constraints on the recycling of specific car modules are included in the discussion of the results when applicable. On this basis, DfR and disassembly recommendations are also included.

The simulations are performed for each of the car modules separately to assess the individual recycling rate per module (and its composing materials), as well as to determine the effect of additional dismantling on the recycling performance and recovery of individual materials. By discussing the various cases, the critical issues in the composition of the car modules are intrinsically addressed. This illustrates and reveals at the same time if and in what manner similar car module types from different models can or cannot be best processed in the same route. Although not part of this paper, simulations and calculations could also similarly be performed for a mix of different car modules (from similar or other car models) by considering their individual compositions and masses.

5. Results of Recycling Assessment

This section will present and discuss the results of the recycling assessment based on the process and methodology as described in the abovementioned sections of this paper.

5.1. Model Definitions and Set Up for Recycling Assessment of Car Modules Selected for Disassembly

As pointed out in Section 3, the data of the different car modules as provided by SEAT and analyzed and are integrated as input into the HSC Sim 10.0 simulation models, as depicted by Figure 1, Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7.

5.2. Assessment of Different Recycling Routes for Recycling of Car Modules and Sub-Modules

Figure 1 shows a screen capture of (and a section of) the “Feeds” pane of the simulation model. Figure 4 shows the input composition (and material combination) included in the models as described in detail in Section 3. This Feed “sheet” of the model of Figure 1 directs all flows of the modules to the correct and most suitable (i.e., with the highest recovery and lowest losses and emissions) metallurgical processing infrastructure (segments in Metal Wheel in Figure 1) based on the composition of the car module.

As pointed out above, the composition of the selected car modules for disassembly is highly distributed and very inhomogeneous due to, among others, functionality reasons. The car modules are composed of a complex mix of metals, materials, and compounds and a complex functional combination of the materials and metals within the different segments of the Metal Wheel, of which the processing cannot therefore be covered by one single metallurgical recycling infrastructure, as depicted by the Metal Wheel. As this complex mixture of functional materials is connected and combined within one car module, there is no one best option to process these different modules, as each of the processing options leads to the recovery of certain elements and the inevitable losses of others, as depicted qualitatively by the Metal Wheel. This implies that the most suitable processing option cannot be defined upfront. Therefore, for each car module, based on its composing material composition, the two or three best options are selected based on the full metallurgical recycling infrastructures available and depicted in the Feed sheet of Figure 1 and recycling system flowsheet of Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7, rather than preselecting one best option upfront. The following processing routes are assessed to be the most suitable options for the different car modules, unless the composition of these modules directly indicate that more than two options out of the options given below are needed (note these flowsheets are connected to all other refining flowsheets in other TABs:

Cu processing route (see Figure 3) —gives an overview of the processing in terms of reduction and oxidative processing, as well as the cleaning of the slag to create a building material quality product.
Steel processing (see Figure 5)—simplified but with sufficient detail to create a complex iron alloy.
Energy recovery (see Figure 6)—simplified and operates to create calcine (or pyrolysis product) and energy.

For each of the three major operating segments that are used, i.e., copper, steel and energy, there are appropriate refining steps that process the intermediate products, process flue dusts, recover valuable products, and clean slags to produce building materials, etc., as shown by the Metal Wheel. Figure 7, for example, represents a typical refining flowsheet producing a variety of technology elements, and the other TABs of the complete flowsheet recover the elements as high-grade products, including the recovery of volatile compounds from the flue dust.

The additional disassembly (level 2) of car modules reduces the complexity of the composition (although the sub-modules are still a complex mixture of materials). Based on a careful study of the module compositional analyses as derived from the data processing (see examples in Table 1), the sub-modules of the Combi-instrument are directed to the most suitable processing route, depending on the sub-module composition.

In the next sections, the results of the recycling assessment for the different car modules will be discussed and elaborated on based on the processing of the car modules in the recycling routes listed above, which are selected from the entire range of processing infrastructures represented in the different segments of the Metal Wheel (Figure 1) as the most suitable options for the processing of the car modules.

The RIs are hence provided for the three defined levels of the CE in recycling. Energy recovery from feed is also included in the presentation of the results, such as the use of organic materials in the smelting process(es) both as a reductant material as well as energy carriers. Replacing the addition of primary resources is standard industrial practice to achieve the required thermodynamic, kinetic, and processing conditions for processing. This differs, however, per type of recycling route, as is shown in the presentation of the results below.

5.3. Results of Recycling Assessment Different Car Modules (Level 1 Disassembly)

In this section, the results of the performed recycling assessment of the assessed car modules are given and described. The major findings and results are included in this section. This is a rather unique picture of the complexity of the products and shows how difficult it is to simply give recycling rates. Each module has a different recycling rate, and the same is true for the elements. Policy should be guided by these results and not by simplistic recycling rates defined by an unclear basis.

5.3.1. Results of Recycling Assessment Infotainment Unit of Leon II

Composition of Car Module

Figure 8 shows the major composing materials/compounds of the Infotainment unit of Leon II. What immediately becomes clear is the low mass-based content of Cu and related valuable (incl. part of the CRM) materials. The Fe content is very high; however, many other elements/materials/compounds are present. The percentage of organics is also relatively high (close to 20%). Due to the high Fe content (close to 65%), the presence of Cu (over 4%) and associated metals as depicted in the Cu segment of the Metal Wheel, and the relatively high content of organic compounds (close to 20%), the Cu processing route (Figure 3), steel processing route (Figure 5) and energy recovery (Figure 6) processing routes for the recycling of the Infotainment unit are assessed.

Overall/Total Recycling Rates

The overall recycling rate of a product can be visualized by the application of the Recycling Index (RI) [1]. It visualizes the overall recycling rate of a product or module in a clear and easy-to-understand manner. Figure 2 is presented to render the legend of the figure readable in view of the use of the Recycling Index in the figures (starting with Figure 9), presenting the recycling performance of the different processing routes for the different level of CE as defined above. The overall recycling rate for the Infotainment unit of Leon II for the three assessed routes is given in Figure 9. Please note that the recycling rate is presented relative to the total weight of the product or module. As an example, this implies that, e.g., when only 5% of copper is present in the module and Cu is fully recovered, the overall recycling rate is only 5% despite the high recycling rate of Cu itself (which is presented in the Material Recycling Flower below). The Recycling Index shows the sum of all recovered materials relative to the total product. Figure 9 presents the overall recycling results for the Infotainment unit for the different recycling routes and different levels of circularity.

Individual Material Recycling Rates

As is depicted by Figure 9, although the recycling rate is low due to the low level of Cu and related metals, resulting in a G-class overall recycling rate (as explained above), only the Cu processing route for the processing of the Infotainment unit of Leon II produces high-quality closed-loop CE products (see level 1 in Figure 9), without further sorting or upgrading required. Hence, it is only realistic for this route to present the individual material recycling rates. The Material Recycling Flower in Figure 2 depicts the individual elemental recycling rates of a selection of materials/elements/compounds that are recycled into high-quality products. This visualizes the individual material recycling rates and illustrates the differences in recycling behavior and performance of different elements/materials also relative to the total recycling rate. The Material Recycling Flowers allow for a transparent visualization of the individual materials/element recycling/recoveries and a comparison between the performance and differences between the various recycling routes and car modules while considering the complete module at the same time. This makes obsolete any cherry-picking outside the context of the complete composition of a module.

In the overall recycling performance, the materials and/or elements that have a low mass contribution relative to the total weight of the product are not well presented and do not contribute significantly to the overall recycling rate. Their recyclability cannot be deduced from the overall recycling rate presented in the Recycling Index. This is also the way recycling is generally reflected. Therefore, the overall recycling rate is not sufficient to present recycling results for the car module under consideration. Presenting the individual material recycling rates of materials/elements, which are present in low percentages, as is the case for the most valuable and critical (CRM) materials, requires the detail presented by the Material Recycling Flower. Comparing individual material/elemental recycling rates is crucial when selecting the most optimal recycling option and will differ for different car modules, depending on the materials or elements defined as critical to recover. In view of the CE, the quantification of and, if possible, increase in recovery rates of individual materials, even when low in weight, are of high importance. The individual material recycling rates for the processing of the Infotainment unit of Leon II in the Cu processing route are presented for a selection of elements in Figure 10.

Discussion of Results of Recycling Processing of Infotainment Unit from Leon II

Cu processing route

It is crucial to understand, due to the complex combination of functional materials in this car module, that significant losses during recycling are inevitable. Figure 8 reveals that the Cu content is very low. Due to the low level of Cu and related metals present in the Infotainment unit of Leon II (see green bullets in the copper segment in the Metal Wheel), only a small module of the car module can be recovered into valuable metals with a high quality to realize a closed-loop CE, such as Cu, Ag, Au, In, Sn, Pb, Pd, Pt, Ni, Co, and Zn. The other metals present in the car module, which are not compatible with the Cu processing route, such as Al, Ba, Ca, Fe, Mg, and Si (also present as Al₂O₃, BaO, CaO, FeO_x, and SiO₂), are recovered in the slag, which is an open-loop CE product. Off-gas elements, such as Br, Cl, Cd, C, H, F, O, S, I, N, etc., will be directed to the flue dust and off gas, which is also an open-loop CE (intermediate) product. In the copper segment of the Metal Wheel, organics and plastics are used as energy carriers and reductant material in the process. This is often the best economic and technological option as these complex mixtures of organic materials cannot be recovered (or, in other words, unmixed) to the same quality (except for physically present plastics, which can potentially be further disassembled if the construction of the car module allows for this).

However, due to the low copper grade in the car module, the copper routes require additional heat to heat slag for a specific operating point, i.e., these modules are processed on a backbone of copper metallurgy. Usually processing of these modules will be integrated and mixed with other copper and valuable materials and processed together to render processing economic.

Steel processing

The product of the steel processing route is a highly contaminated iron rich alloy, which carries many elements, some of which are harmful for steel metallurgy as these are deleterious to the standard steel alloy specifications. Due to the low nobility of the Fe, many elements will dissolve into the iron alloy (see also the Fe segment in the Metal Wheel). The iron alloy hence contains a wide range of metals, which are except for the alloying elements as required for steel processing (see the elements in green elements in the Metal Wheel) undesired or are even harmful to the alloy specifications. This includes next to Fe, other metals such as, Pb, Cr, Co, Au, Cu, Mn, Mo, Ni, Ag, V, Sn, Sb, As, Bi, Ga, In, Pd, Ru, Ta, Nb, W, Ge, Pt, C, Be, S and Zn. It must be noted, if iron is a collector of Au, Ag, Pt, Pd, Re, etc. there are process routes to oxidize/convert the Fe to slag, while concentrating these economically valuable elements for further hydrometallurgical processing. However, the car modules under consideration do not meet these requirements.

The alloy has also a significant C content (reaching cast iron), originating among others from organics, which may to an extent dissolve into the alloy if it does not oxidize to CO₂ and CO. To render this alloy to a closed-loop CE product, this alloy must be diluted by pig iron or Direct Reduced Iron (DRI), but this may not achieve the tight specifications of steel alloys and carries with it the carbon footprint of the primary pig iron production. Therefore, this has a negative environmental consequence due to the addition of high amounts of primary sources, while nevertheless the many harmful elements will also then have a negative impact as mentioned due to steel alloy specifications. This alloy may also be used as a reductant in non-ferrous metallurgy; however, it would be better to send the car module directly to one of the other processing routes. DfR or additional disassembly can change this situation if this mitigates the deportation of harmful elements into the EAF (Electric Arc Furnace). The slag produced during the steel processing will contain Al, Ba, Ca, Mg, and Si (present as Al₂O₃, BaO, CaO, MgO, SiO₂, and their solid compounds etc.). Volatile elements will be sent to the flue dust. These fractions could be applied in an open-loop CE. Due to the high level of other metals present together with the Fe, in this route, a high input of both primary resources and energy is required. As the EAF is a smelter, using power for the electrodes, no energy recovery from the organics takes place in this route.

Energy route

In the energy recovery route, the car module is processed with the major purpose of recovering the energy contained in the organic compounds of the car module, which constitutes a relatively high percentage of its composition (see Figure 8). In this process, metal phases and calcine are also produced. These are both open-loop CE fractions, which require further physical sorting into different metal fractions (the metal phase) and chemical upgrading, e.g., by being processed in the Cu processing route (sorted metals and calcine) to achieve the required high-quality material properties/alloy quality to render a closed-loop CE. However, smelting this “junk” has an economic cost and is not desirable from an exergetic point of view.

Environmental indicators/assessment linked to recyclability analyses in recycling process simulation models

As environmental impact calculations are directly linked in HSC Sim, LCA indicators and an assessment on the EoL can be calculated from this. Recent work has combined processing with LCA and exergy to quantify the quality loss of material through the CE [1]. Table 2 illustrates that environmental indicators (including an exergy assessment—not shown here) can be calculated for the selection of the most suitable and optimal recycling processing route. These are Scope 1 and are directly calculated by the simulator.

Conclusions

Despite the low recovery rate, the best option for processing the Infotainment unit from Leon II in its current composition is processing via the Cu processing route, where high-quality closed-loop CE products can be realized. A recommendation for additional disassembly would therefore be to separate the high-Fe-containing and high-organics-containing sub-modules from the Cu and related metal-based modules or components. In this manner, the concentration of valuable elements can be increased in the Cu-based module, the presence of harmful elements in the Fe-based modules can be mitigated, and the metal content of the organics-based fraction for energy recovery can be decreased. This would allow (if possible, from a design and disassembly point of view) us to process these three different modules (Cu-based, Fe-based with a low level of contamination metals, and organics-based) in the induvial most suitable processing route. In this way, both the overall and individual material/element recycling rates can be increased, and losses and the required additional physical sorting and/or chemical upgrading (and the related requirement of primary resources/energy) can be minimized or decreased. The creation of low-valuable intermediate materials is therefore, to an extent, mitigated.

DfR as a module of eco-design recommendations could be derived from the recycling assessment. DfR should be focused, when possible, from a functional point of view, on designing modules and harmonizing with the different sections in the Metal Wheel. However, the functionality of the module may limit this. Avoiding, where possible, the mixture of incompatible materials in sub-modules/components, and/or it could be achieved by additional disassembly, if this is possible from a structural design point to view. The individual recycling rates are quantitatively supporting and help in choosing which options in both additional disassembly and/or DfR will have the highest impact in the improvement of recyclability. Also, rarity-based % as defined in TREASURE could be used as a driver to select materials/elements and disassembly and DfR options.

5.3.2. Results of Recycling Assessment Infotainment Unit of Leon III

Composition of Car Module

Figure 11 shows the major composing materials/compounds of the Infotainment unit of Leon III. Like the Infotainment unit of Leon II, it has a low mass-based content of Cu and related valuable (incl. part of the CRM) materials. The Fe content is very high (although lower than Leon II). Also, many other elements/materials/compounds are present. The percentage of organics is also relatively high (close to 20%). Due to the high Fe content (close to 53%), the presence of Cu (close to 6%) and associated metals, as depicted in the Cu segment of the Metal Wheel, and the relatively high content of organic compounds (close to 20%), the Cu processing route (see Figure 3), steel processing route (see Figure 5) and energy recovery (Figure 6) routes for the recycling of the Infotainment unit are assessed, similarly to the assessment of the Infotainment unit of Leon II.

Overall/Total Recycling Rates

The overall recycling rate for this car module for the three assessed routes is given in Figure 12 by the Recycling Index (RI).

Individual Material Recycling Rates

As is clearly visible from Figure 12, also for this car module, like the Infotainment unit of Leon II, only the Cu processing route for the processing of the Infotainment unit of Leon III produces high-quality closed-loop CE products, without further sorting or upgrading required. Hence, also for this car module, it is only realistic for this route to present individual material recycling rates, similarly to the Infotainment unit of Leon II. The Material Recycling Flower (Figure 13) depicts the individual elemental recycling rates of a selection of materials/elements/compounds that are recycled into high-quality products for the Infotainment unit of Leon III.

Discussion of Results of Recycling Processing of Infotainment Unit from Leon III

The overall recycling results as presented in Figure 12 and individual material recycling rates as shown in Figure 13 show that the results of the recycling assessment of the Infotainment unit of Leon III are comparable with the results of Leon III. Due to the (small) differences in composition, minor differences in the recyclability of both modules of the two car types can be observed. However, the discussion of the results of the Infotainment unit from Leon II is equally valid for Leon III. Therefore, these results are not repeated here, but please refer to Leon II for a discussion of the results.

Conclusions

As the results of the recycling assessment of the Infotainment unit of Leon III are comparable to that of Leon II and composition is comparable (despite small differences), the conclusions defined for Leon II are equally applicable for the car module type of Leon III (see Leon II).

Figure 13. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product from the Infotainment unit of Leon III (in the other two routes, no closed-loop high-quality product is produced directly from the route).

5.3.3. Results of Recycling Assessment Combi-Instrument of Leon II

Composition of Car Module

Figure 14 shows the major composing materials/compounds of the Combi-instrument of Leon II. This module is characterized by a very low Cu and related valuable material (incl. part of the CRM) content (see metals in green dots in the Cu segment of the Metal Wheel). The Cu and related valuable metal concentration lies under 4%. The Fe content is very low (<2%) and differs significantly from the Infotainment unit modules. The percentage of organics is very high and composes almost 73% of the module. The high organics content a priori dictates that no high or even reasonable recycling rate can be achieved for this type of module. Only the recovery of the energy content of the organics lies within the options of recycling, if possible, combined with the recovery of the Cu and Cu-related metals.

Due to the very low Fe content, processing this car module type in the steel processing route is not feasible at all. Despite the low presence of Cu and associated metals, as depicted in the Cu segment of the Metal Wheel, and the focus on the recovery of the minor materials (incl. CRMs) from EoL vehicles, the recycling of the Combi-instrument is assessed for the Cu route, in which the module containing high organics content can also be partially recovered. The very high content of organic compounds dictates that the energy processing route (Figure 6) should be included in the assessment, in addition to the Cu processing route (see Figure 3), for the recycling of the Combi-instrument.

Figure 14. Major material classification of the Combi-instrument of Leon II (simplified classification due to confidentiality reasons).

Overall/Total Recycling Rates

The overall recycling rate for this car module for the two assessed routes is given in Figure 15 by the Recycling Index (RI).

Individual Material Recycling Rates

Figure 15 clearly shows that, once again, only the Cu processing route produces high-quality closed-loop CE products, without further sorting or upgrading required. Hence, only for this route, the individual material recycling rates (for a selection of elements) are presented in the Material Recycling Flower of Figure 16.

Discussion of Results of Recycling Processing of the Combi-Instrument from Leon II

Cu processing route

The composition of the Combi-instrument of Leon II, Leon III and Ibiza is characterized by a low Cu content and an even lower Fe content (Figure 14, Figure 17 and Figure 20). Due to the low level of Cu and related metals present in the Combi-instrument (see green bullets in the copper segment in the Metal Wheel), only a small module of the car module can be recovered into valuable metals with a high quality to realize a closed-loop CE, such as Cu, Ag, Au, In, Sn, Pb, Pd, Pt, Ni, Co, and Zn. Various other elements and compounds report to the phases mentioned previously. The Combi-instrument is very high in organic content. In the copper segment of the Metal Wheel, i.e., the Cu processing route, organics and plastics are used as energy carrier and reductant in the process. This is often the best economic and technological option, as these complex mixtures of organic materials cannot be recovered (or in other words unmixed) to the same quality (except for the physically present plastics, which could potentially be further disassembled if the construction of the car module allows for this). Similarly, as for the Infotainment unit, due to the low copper grade in the car module, the copper route requires additional heat to heat slag for a specific operating point. Usually processing of these modules will be integrated and mixed with other copper and valuable materials and processed together to render processing economic.

Steel processing route

Due to the very low Fe content, the steel processing route provides no feasible option to recycle the Combi-instrument when being processed in its total composition.

Energy route

In the energy recovery route, the car module is processed with the major purpose of recovering the energy contained in the organic compounds of the car module. Due to the very high presence of organics, this processing route can be considered the most suitable to process the Combi-instrument when no further disassembly takes place to concentrate the valuable metals separate from the organic modules. Although, in this process, a metal phase and calcine are also produced, these are both open-loop CE fractions, which require further physical sorting into different metal fractions (the metal phase) and chemical upgrading, e.g., by being processed in the Cu processing route (sorted metals and calcine) to achieve the required high-quality material properties/alloy quality to render a closed-loop CE. The energy recovery per ton of input is considerably higher than the amount of energy recovered in the Cu route.

Conclusions

The selection of the best processing route for the Combi-instrument of Leon II depends on the objective of the recycling. There is no one best route. When the focus is to recover as much (valuable and critical) metals from the car module, the most preferred option, from a closed-loop CE point of view, is to process this module in the Cu route. Despite the low recovery rate, in the Cu processing route, high-quality closed-loop CE products can be realized, while at the same time, the recovery of (part of the) energy contained in the organics fraction is realized. It has to be considered, however, that due to the low Cu content, the recycling of this car module requires a significant input of heat and primary resources to obtain the correct operation point. This can be considered as a negative point for this processing route. Exergetic analyses of the recycling process can reveal this balance very well. In practice, the car module would have to be processed together with other recyclates and input flows, with a much higher Cu and valuable metal content.

Due to the very high organics content, the energy processing route is the best option to recover the energy contained in these organics. In this process, a metal phase and calcine are also produced. However, these are both open-loop CE fractions, which require further physical sorting into different metal fractions (the metal phase) and chemical upgrading, e.g., by being processed in the Cu processing route (sorted metals and calcine) to achieve the required high-quality material properties/alloy quality to render closed-loop CE.

A recommendation for additional disassembly would therefore be to separate the organics containing sub-modules from the Cu and related metal-based modules or components. In this manner, the concentration of valuable elements can be increased in the Cu-based module, while the metal content of the organics-based fraction for energy recovery can be decreased. In general, this implies that, according to physics-based disassembly recommendations, the mixture of incompatible materials in sub-modules/components must be separated as much as possible into different sub-modules, when this is possible, from a structural design point to view. This would facilitate (if possible, from a design and disassembly point of view) processing the car sub-modules as derived from additional disassembly (Cu- and organics-based) in the most suitable processing route. In this way, both the overall and individual material/element recycling rates can be increased, and the losses and required additional physical sorting and/or chemical upgrading (and the related requirement of primary resources/energy) can be minimized or decreased. The creation of low-valuable intermediate materials is therefore, to an extent, mitigated. In the case of the Combi-instrument, it could also be considered that, in the organics-containing modules, to physically separate organics and dismantlable plastics, via physical recycling into a new high-quality plastic products. Important to note is that plastic recycling might be limited due to possible additives and fillers in the plastics, or there may be a mix of plastics, for which the quality demands for plastic processing cannot be met.

This additional disassembly was investigated in TREASURE and matches with the recommendations, as given above, based on the assessment of the level 1 disassembly of the Combi-instrument of Leon II (and other models). The results of the additional level 2 disassembly are assessed in this study and are discussed in Section 5.4 below.

DfR, as part of eco-design recommendations, can also be defined based on the performed recycling assessment. DfR should be focused, when this is possible from a functional point of view, on designing modules in which their composition is harmonized with the compatibility of the metals in the different sections in the Metal Wheel. However, functionality of the module may limit this. The individual recycling rates as calculated in the recycling assessment, quantitatively support and help choose which options in both additional disassembly and/or DfR will have the highest impact in the improvement of recyclability. In addition, rarity-based %, as defined in TREASURE [29], could be used as a driver to select materials/elements and disassembly and DfR options.

5.3.4. Results of Recycling Assessment of Combi-Instrument Leon III

Composition of Car Module

Figure 17 shows the major composing materials/compounds of the Combi-instrument of Leon III. As the content is comparable to that of the Combi-instrument of Leon III, the same recycling routes are assessed to process this module. The organic content is even higher than in the Combi-instrument of Leon II. Also, the Cu content is slightly higher but still low in absolute terms.

Figure 17. Major material classification of the Combi-instrument of Leon III (simplified classification due to confidentiality reasons).

Overall/Total Recycling Rates

The overall recycling rate for this car module for the assessed routes is given in Figure 18 by the Recycling Index (RI).

Individual Material Recycling Rates

Figure 19 presents the individual material recycling rates for the Combi-instrument of Leon III in the Cu route, as only in this route, valuable metals are recovered with a high quality, allowing for a closed-loop CE, without further processing required.

Discussion of Results of Recycling Processing of the Combi-Instrument from Leon III

The overall recycling results as well as individual material recycling rates of the Combi-instrument of Leon III show that the results of the recycling assessment of the Combi-instrument of Leon III are comparable to the results of Leon II. Due to the (small) differences in composition, minor differences in the recyclability of both modules of the two car types can be observed. However, the discussion of the results of the Combi-instrument from Leon II is equally valid for Leon III.

Conclusions

As the results of the recycling assessment of the Combi-instrument of Leon III are comparable to that of Leon II and its composition is similar (despite small differences), the conclusions defined for Leon II are equally applicable for this car module type of Leon III.

5.3.5. Results of Recycling Assessment of Combi-Instrument Ibiza IV

Composition of Car Module

Figure 20 shows the major composing materials/compounds of the Combi-instrument of Ibiza IV. As the content is comparable to that of the Combi-instrument of Leon II and III, the same recycling routes are assessed to process this module. The organic content is the highest compared to that of the Combi-instrument of Leon II and III (almost 80%). The Cu content is comparable to that of Leon III (a bit lower than 6%), but still very low in absolute terms. The same applies to the Fe content (<2%).

Overall/Total Recycling Rates

The overall recycling rate for this car module for the assessed routes is given in Figure 21 by the Recycling Index (RI).

Individual Material Recycling Rates

As is clearly visible from Figure 21, despite the low recycling rate, only the Cu processing route for processing the Combi-instrument of Ibiza IV produces high-quality closed-loop CE products, without further sorting or upgrading required. Hence, it is only realistic for this route to present individual material recycling rates, similarly to this module of Leon II and III. The Material Recycling Flower (Figure 22) depicts the individual elemental recycling rates of a selection of materials, elements and compounds that are recycled into high-quality products for the Combi-instrument of Ibiza IV.

Discussion of Results of Recycling Processing of the Combi-Instrument from Ibiza IV

The overall recycling results and individual material recycling rates of the Combi-instrument of Ibiza IV show that the results of the recycling assessment of the Combi-instrument of Ibiza IV are comparable to the results of Leon II as well as Leon III. Due to the (small) differences in composition, minor differences in the recyclability of both modules of the three car types can be observed. However, the discussion of the results of the Combi-instrument from Leon II (and Leon III) is equally valid for Ibiza IV.

Conclusions

As the results of the recycling assessment of the Combi-instrument of Ibiza IV are comparable to that of Leon II and III and its composition is similar (despite small differences), the conclusions defined for Leon II and III are equally applicable for this car module type of Leon III.

5.3.6. Results of Recycling Assessment of Additional Brake Light Leon II (Mirror/Lighting)

Composition of Car Module

Figure 23 shows the major composing materials/compounds of the Additional Brake Light of Leon II. This graph clearly shows that this module comprises mainly organics (almost 95%). The concentration of Cu and related metals is very low (close to 1%). The Fe content lies around 0.04%. The composition determines that, in fact, only energy recovery is a feasible option for the processing of this module in its current composition (without further separation of the plastics from the module). To also include the option of recovering a small percentage of Cu and related metals from the module, the Cu route is, despite the very low Cu content, included in the assessment. The Cu processing route (see Figure 3) and the energy recovery (Figure 6) routes are assessed to determine the recyclability of this module.

Overall/Total Recycling Rates

The overall recycling rate for this car module for the assessed routes is given in Figure 24 by the Recycling Index (RI).

Individual Material Recycling Rates

Despite the low recovery rates, the Cu route is the only route in which high-quality closed-loop CE products are obtained. Hence, only for this route, the individual recycling rates are presented by the Material Recycling Flower in Figure 25.

Discussion of Results of Recycling Processing of the Additional Brake Light of Leon II

Cu processing route

The composition of the Additional Brake Light is, like for the Combi-instruments, characterized by a low Cu content and very low Fe content. Comparable to the processing of the Combi-instrument, from the Additional Brake Light, only a small part of the car module can be recovered into valuable metals of a high quality. The Additional Brake Light is very high in organic content, even higher than in the Combi-instrument. Also, for this module, in the Cu processing route, organics and plastics are used as energy carriers and reductant material in the process. As for the Combi-instrument and the Infotainment unit, the low copper grade in the car module requires the copper route to operate under additional fuel load to ensure an economically viable operating point is achieved. Usually, the processing of this type of module will also be integrated and mixed with other copper and valuable materials and processed together.

Steel processing route

Due to the very low Fe content, the steel processing route provides no feasible option to recycle the Additional Brake Light.

Energy route

Due to the very high presence of organics, the energy processing route can be considered the most suitable to process the Additional Brake Light, if no further disassembly takes place, to concentrate the valuable metal-containing modules and separate them from the organics-based modules. Like the processing of the other car modules, in this process, a metal phase and calcine are also produced. These are, however, both open-loop CE fractions, which require further physical sorting into different metal fractions (the metal phase) and chemical upgrading, e.g., by being processed in the Cu processing route (sorted metals and calcine) to achieve the required high-quality material properties/alloy quality to render a closed-loop CE. The energy recovery per ton of input is considerably higher than the amount of energy recovered in the Cu route and the highest for all assessed car modules.

Conclusions

The selection of the best processing route for the Combi-instrument of Leon II depends on the objective of the recycling. There is no one best route. When the focus is to recover as much (valuable and critical) metals from the car module, the most preferred option, from a closed-loop CE point of view, is to process this module in the Cu route. Despite the low recovery rate, in the Cu processing route, high-quality closed-loop CE products can be realized, while at the same time, the recovery of (part of the) energy contained in the organics fraction is realized. As discussed for the processing of the Combi-instrument, it must be considered that, due to the low Cu content, recycling this car module requires a significant input of heat and primary resources to obtain the correct operation point. This can be considered as a negative point for this processing route. Due to the very high organics content, the energy processing route is the best option to recover the energy contained in these organics. In this process, metal phases and calcine are also produced. However, these are both open-loop CE fractions, which require further physical sorting into different metal fractions before these can be further processed to achieve the required high-quality material properties/alloy quality to render a closed-loop CE. Recommendations for additional disassembly and DfR are like the recommendations above.

5.3.7. Results of Recycling Assessment of Additional Brake Light of Leon III (Mirror/Lighting)

Composition of Car Module

Figure 26 gives the composition of the Additional Brake Light of Leon III. This Figure reveals that the composition is comparable to that of this module in Leon III and is characterized by a very high organics content (>85%) and very low metal content. The Cu content and related metal content are, however, a bit higher than those of Leon III (<6%). Therefore, the Cu processing route (see Figure 3) and energy recovery (Figure 6) routes are assessed to process this module (like Leon II).

Overall/Total Recycling Rates

The overall recycling rate for this car module for the assessed routes is given in Figure 27 by the Recycling Index (RI).

Individual Material Recycling Rates

Despite the low recovery rates, the Cu route is the only route in which high-quality closed-loop CE products are obtained. Hence, only for this route, the individual recycling rates are presented by the Material Recycling Flower in Figure 28.

Discussion of Results of Recycling Processing of the Additional Brake Light of Leon III

The overall recycling results and individual material recycling rates of the Additional Brake Light show that the results of the recycling assessment of this module of Leon III are comparable to the results of Leon II. Due to the (small) differences in composition, minor differences in the recyclability of both modules of these car types can be observed for this car module. The Cu content of the Additional Brake Light of Leon III is slightly higher, therefore resulting in a slightly higher recycling rate of Cu and related valuable metals in the Cu route. The discussion of the results of the Brake Light of Leon II is equally valid for that of Leon II.

Conclusions

As the results of the recycling assessment of the Brake Light of Leon III are comparable to that of Leon II and its composition is quite similar (despite small differences), the conclusions defined for Leon II and III are equally applicable for this car module type of Leon III.

5.4. Results of Recycling Assessment After Additional Disassembly (Level 2) of the Combi-Instrument of Leon II

Within TREASURE, the disassembly of the car modules is investigated. To determine the effect of a more in-depth disassembly of the car modules into different sub-modules, which should have a more homogeneous composition due to further disassembly (e.g., disassembly into PCB-containing modules, plastic modules and Fe-based modules), the recycling of the level 2 disassembly for the case of the Combi-instrument of Leon II is assessed. The results are discussed in this section and compared to those of the recyclability of the Combi-instrument without further disassembly, as discussed in Section 5.3.3.

5.4.1. Composition of the Sub-Modules of the Combi-Instrument of Leon II

The Combi-instrument of Leon II is further disassembled into three main fractions/modules, which, for some modules, consist of different sub-modules (but are considered here as one module; however, this can be further separated if needed from a recycling point of view), as follows:

Plastic/organic modules (four different modules dismantled)—74.3 mass% of the Combi-instrument.
PCB-containing modules (three different modules dismantled)—25.5 mass% of the Combi-instrument.
Ferrous-based modules (one module dismantled)—0.2 mass% of the Combi-instrument.

These three fractions comprise the entire Combi-instrument, and no remaining modules are left after disassembly. The mass distribution over the three different fractions/modules reveals that the ferrous module only covers a very small fraction of the total Combi-instrument. Figure 29 shows the composition of the different sub-modules of the Combi-instrument of Leon II after disassembly. When comparing these graphs to that of the composition of the Combi-instrument, it becomes immediately clear that the additional disassembly of the Combi-instrument into plastic-, PCB- and ferrous-based sub-modules creates sub-modules, with a much more segregated composition, matching better with the different sections of the Metal Wheel, i.e., the compatibility of materials within the different metallurgical (and plastic/organics) processing routes.

Figure 29a reveals that the composition of the plastic modules is characterized by a high percentage of plastics/organics, which is higher than 85% on average. When looking at the four different plastic modules, it becomes apparent that three out of four modules consist of (almost) 100% plastics/organics and the one other module contains a percentage of inorganics and other metals, which affects the average composition of these plastic modules. Figure 29b shows that the PCB modules are significantly higher in Cu and valuable metal content compared to the Combi-instrument without disassembly. Figure 29b reveals that the PCB modules still have an average Fe content of more than 6% and a light metals content of more than 7%. Both Fe and light metals are not recovered as metals but are directed to the slag. Also, the organic fraction is very high in these modules (>65%), which is also directed to the slag. Comparing the composition of the two individual PCB modules reveals a large spread in, e.g., Cu content (38% versus 7%), Fe content (34% versus 2%), SiO₂ content (10% versus 72%) and light metal content (0% versus over 8%). Figure 29c reveals that the ferrous-based module is characterized by a very high Fe content (>90%), which is a significant difference with the Combi-instrument without further disassembly (Figure 14).

Based on their content and their average composition, the following recycling routes are assessed for the processing of the different sub-modules, which are, in this case, processed as the sum of the different sub-modules. The difference in composition between the sub-modules of the same category can, however, lead to a difference in recycling performance if processed/assessed as separate modules. This is not considered here but can be included at a later stage to support disassembly decisions and DfR in more detail.

Cu processing route for the processing of the PCB-based modules.
Steel processing route for the processing of the ferrous-based module.
Energy recovery for the processing of plastics/organics-based modules.

5.4.2. Overall/Total Recycling Rates

The overall recycling rate for this car module for the assessed routes is given in Figure 30 and Figure 31 by the Recycling Index (RI). The crucial difference with the results of the recycling of the entire car module without further disassembly is that, in this case, all results are achieved and not just with one of the routes as all modules are processed in their most suitable recycling route, implying that all routes are applied at the same time for each of the different modules. This reveals the true benefit and positive effect of additional disassembly on recycling performance. The recycling rates for the total car module (Combi-instrument) based on the processing of the sub-modules in the most suitable processing routes, as discussed, are given in Figure 30 and Figure 31.

5.4.3. Individual Material Recycling Rates

Figure 30 and Figure 31 show that both in the Cu route and the steel processing route, high-quality closed-loop CE products are obtained. Therefore, for both module types, the individual material recycling rates can be presented (see Figure 32). Figure 32 makes clear that, e.g., Fe can now be additionally recovered to high rates. The high recovery of Cu in the steel processing route is unwanted as this is a harmful element in steel processing and results in a decrease in the iron alloy quality.

5.4.4. Discussion of Results of Recycling Processing of the Car Sub-Modules After Additional Disassembly (Level 2) of the Combi-Instrument of Leon II

Figure 30, Figure 31 and Figure 32 show that both Cu and related valuable metals, as well as ferrous in the ferrous module, can be recovered at the same time. Also, the high recovery of energy from the plastic/organics modules in the energy route can be achieved simultaneously. As each module is directed to the most appropriate recycling route, no choice must be made here. This is different from the results for the non-disassembled modules. Figure 30 and Figure 31 also make clear that the creation of lower-quality, open-loop products such as slags and flue dust is much lower than when the Combi-instrument is processed in its totality. This is thanks to the fact that the streams better match the processing capabilities of the applied processing routes, and the presence of slag forming or volatile components (ending up in the flue dust) is much lower. Also, the creation of a metal mix during energy recovery is avoided as no (or a very low amount of) metals are present in these modules.

The effect of the disassembly (level 2) might not become directly apparent when looking at the total recycling results for the Combi-instrument, as given in Figure 31 (based on the summation of the three applied processing routes, one for each fraction/module). This figure does not show a significant increase in the total recycling rate compared to the processing of the Combi-instrument without dismantling. However, the additional disassembly has clear effects on the recycling efficiency as follows:

Both Cu and valuable metals (mainly contained in the PCB modules) as well as energy from the plastics/organic compounds can be recovered at the same time, without having to make a choice between one or any other processing option.
The ferrous material can be recovered to a relatively high-purity alloy.
The individual material recycling rates (e.g., for Cu and Fe) are higher.
The creation of open-loop CE products (slag and flue dust) is (to an extent) mitigated due to the much more segregated composition of the different modules. Losses and the required additional physical sorting and/or chemical upgrading (and the related requirement of primary resources/energy) are therefore minimized or decreased.

This assessment could be extended by an assessment of the possibility of the physical recycling of (some of) the plastic modules to transform them into new high-quality plastic products. This would also require detailed information on the type of plastics applied, the quality requirements of the manufacturer for adopting high-quality recycled plastics, and information on, e.g., quality degradation during recycling and/or use.

Since the Fe content in the Combi-instrument is very low (see Figure 14), it is evident that the disassembly and separate processing of this ferrous module is not contributing much to the increase in the recycling rate in total in this case. This will, however, be different for modules with a high Fe content, such as the Infotainment unit, which is characterized by a very high Fe content (which can, according to the recycling assessment, only be recovered as a very impure alloy that needs a high input of primary processing to be diluted). For the Infotainment unit, it can already be predicted, based on the results of the level 2 disassembly on recycling, that for this module, the increase in recyclability will be much more evident. This should, however, be taken care of, by an additional disassembly of the Fe fractions of, e.g., the Infotainment unit, whereby the presence of harmful elements for iron/steel production (such as Cu, Sn, Sb, etc.) can be separated from the Fe module(s) to ensure a high enough quality of the produced iron alloy.

5.4.5. Conclusions on the Effect of Additional Disassembly on Recycling Performance

The recycling assessment on the level 2 disassembly for the Combi-instrument from Leon II reveals that separating sub-modules, with a more comparable composition, that match the different segments in the Metal Wheel allows for a better recyclability of the car module. This can be observed via the following:

An increase in the total recovery (although this depends very much on the mass contribution in the total module of each of the separated leading materials (e.g., Fe content, Cu content, etc.)) of the product into closed-loop CE high-quality products that meet the functional requirements.
An increase in the recovery of the individual elements/materials.
A mitigation of the creation of open-loop CE products (such as slags/flue dust).
A recovery of (in)compatible materials, which is possible via different processing routes.
An ability to recover both (valuable) metals and energy content, without losses of valuable metals e.g., as open-loop CE products (to be processed into a closed-loop CE) such as mixed metal alloys and/or calcine.

As level 2 disassembly changes the composition of the different car (sub-)modules, the model-based approach allows for the optimization of the system architecture of the physical and metallurgical recycling processes linked to this improved disassembly strategy. Each sub-module or component can be directed into the most optimal recycling route, through which both metal recovery and energy recovery are optimized and the creation of losses and dissipation of energy and exergy can be minimized. A recommendation to guide the disassembly for both level 2 and 3 is to pay special attention to minimize the presence/mix of incompatible materials to reduce the presence of elements that could be harmful to steel processing. In this way, dilution by primary materials to obtain the required alloy quality, and the related environmental impact thereof, can be minimized or avoided.

5.5. Results of Recycling Exergy Assessment of the Combi-Instrument of Leon II

The focus of this paper is on quantifying the recycling rates of the various modules discussed in this paper. To an extent, the environmental impacts were provided. This section shows that one can also estimate the exergy [35] dissipation while recycling the modules. This is discussed as a downward spiral of a circular economy system [1], with reference to numerous papers that discuss this in detail such as [1,15,18]. Figure 33 succinctly shows the significant dissipation of exergy, more than 80% if both copper and slag are products in the shown flowsheet, but at the same time, the recoveries are high. This raises the following significant question: what is a true circular economy? Here, we specifically consider the exergy of the module feed exergy, which is 20 t/h of the material, reduced from 146 MW to 3.6 MW of the copper cathode and 7.9 MW for slag. While these values are indicative, they do highlight significant 2LT dissipation. While Nanz et al. [36] correctly highlight the significance of a systemic view, in the end, if the system is not analyzed rigorously using at least simulation approaches that deliver exergy as an outcome (among others), these discussions remain superficial.

6. Conclusions and Recommendations

This paper uniquely applies a simulation basis to generate a unique body of recycling rate data for seven car modules. This is visualized with a recycling index as well as a material flower.

In addition, this paper created a significant body of data visualizing the large variation in recycling rates achievable for a range of car modules. This is for both the entire car module as well as all individual materials contained, as a function of disassembly depth and different recycling system flowsheet options. This contribution shows the rather complex “mineralogy” or composition of the modules and the effect of this on recyclability and the important role of disassembly actions to improve recyclability.

The following discussion provides a summary of the insights and contributions of this paper. It shows that based on rigorous processing flowsheets incorporating thermochemistry and extensive industrial experience, true recycling rates and energy recovery can be quantified.

6.1. Recycling System Modelling

Complex car modules with intricate functional material combinations can only be analyzed with detailed simulation models. This paper shows the application of the authors’ process simulation model [1] to estimate the recyclability of real functional modules from SEAT cars.

6.2. Data Processing and Automation

This paper shows how a typical MISS file (as provided by SEAT [29]) can be transformed into a useful form so that it can be applied in process simulators. This paper shows that this can be carried out and therefore opens the path to link computer-aided design (CAD) from the automotive industry to recycling simulation models. The authors of this paper already proposed this within the EU’s sixth framework project SuperLightCar [37]. The linkage of computer-aided design with complex simulation tools was, at the time, problematic and development of this has been tardy. It is clearly now possible, as this paper clearly shows, to evaluate the true recyclability of products. Granularity is therefore given to perform true DfR and understand, in real time, the effect of (re-)designs.

6.3. KPIs

We show, in this paper, that by rigorous calculation, Recycling Indices [1] for an entire module, as well as calculations of the individual recycling rates of all materials in a product, car module, sub-module and component, can be carried out. This is presented in terms of the Material Recycling Flowers [1]. Whereas the overall recycling rates provide information on the recyclability of the entire module or product, the individual recycling rates—KPIs—are the basis for true CE assessment. Therefore, the Material Flowers are significant visual tools to help make the choice for a certain recycling route, not only driven by weight-based considerations but addressing the recycling of materials and elements, which are of interest to recycle. This provides the required focus in selecting the most optimal recycling options as a function of design. A clear distinction is made in the circularity level of the recycling KPI viz. closed-loop CE, open-loop CE, and open-loop CE (intermediate), as shown in the results.

In addition to the Recycling Indices, which are expressed in kg/h, t/h or %, physics-based recycling standards based on exergy (kW) and energy (kW) can also be derived from the simulation models. While only briefly shown, the exergy dissipation (kW) is significant, which seriously questions the policies focusing only on recycling rates. The reader is also referred to various examples in the Handbook of Recycling [1], which show various exergetic analyses. This highlights that material flows are also energy flows but degrade in quality, which is expressed as exergy dissipation, which are the true losses of the system.

6.4. Recyclability Results and Most Suitable Recycling Routes for Processing of Car Modules

Depending on its composition and therefore suggested classification, the most suitable recycling routes are assessed to determine their recyclability. This is carried out using Cu (recovering many elements), steel (producing alloys) and energy routes (and calcine that returns to the copper route). There is no one best option to process these different modules. Each of the processing options will lead to the recovery of certain elements and losses of others, as depicted qualitatively by the Metal Wheel [1]. A selection of the best recycling route depends on the focus of the recycling optimization, i.e., whether total recycling rates or specific material recycling rates should be optimized, which can include minimizing exergetic dissipation [1].

The general conclusion on the recyclability of these SEAT modules to maximize the recovery of valuable metals (Cu and associated/compatible materials) is to process them via the Cu processing route, where the valuable metals can be recovered in a high-quality closed-loop CE application. The produced slag and flue dust can be applied as lower-quality open-loop CE applications, and a module of the energy present in the organics is recovered. Due to the low presence of metals in the considered modules, the recycling rate for the modules is very low. Due to their low Cu content, the recycling of the different car modules requires a significant input of heat and primary resources to obtain the correct operation point. This can be considered a negative point for this processing route.

Considering the high content of organics in all modules as well as in the Combi-instrument and Additional Brake Light, energy recovery processing could also be considered a possible option to process these modules to maximize the recovery of the contained energy. However, in this route, a metal phase and calcine are also produced, and these are both open-loop CE fractions, which require further physical sorting into different metal fractions (the metal phase) and chemical upgrading. This can be carried out by following the Cu processing route (sorted metals and calcine) to achieve the required high-quality material properties and alloy quality to render a closed-loop CE. However, smelting this “junk” has an economic cost and is not desirable from an exergetic point of view, as Figure 33 reflects.

The steel processing route is not a feasible option for the processing of entire car modules without further level 2 disassembly. This also applies to car modules with a higher Fe content (e.g., the Infotainment unit) due to the very contaminated, low-quality iron alloy that is created. Due to the presence of many other metals in the car modules, which will dissolve in the alloy, only a low-quality iron alloy is created. To render this alloy a closed-loop CE product, this alloy must be diluted by pig iron or Direct Reduced Iron (DRI), but this may not meet the tight specifications of steel alloys and carries with it the carbon footprint of the primary pig iron production. Therefore, this has a negative environmental consequence due to the addition of high amounts of primary sources, and the many harmful elements will also then have a negative impact as mentioned due to steel alloy specifications. It would be best to simply dissolve the iron in a slag and use the slag as building material while recovering the valuable elements in base metal flowsheets of the Metal Wheel, i.e., copper, nickel, zinc, lead, and tin.

For the processing of the sub-modules, which are created through additional disassembly (level 2), a combination of the different recycling routes (Cu route, steel processing and energy recovery) can be applied. This results in a more optimized recycling of the module under consideration. The additional disassembly permits creating feeds that are better harmonized with the compatibility of the metals and materials that can be processed in the different recycling routes, as shown by the Metal Wheel [1]. In addition to the Cu and energy recovery route, the steel processing route is feasible. These routes can be applied together to process the different sub-modules to achieve the most optimal recycling performance, instead of having to select one recycling route for the processing of the total module, which inevitably leads to losses. However, the disassembly has an increased cost, which is a negative.

6.5. Recommendations on Additional Disassembly and DfR (Eco Design)

Additional disassembly is recommended to optimize the recyclability of the car modules and to ensure plastics and organics are recovered in their original quality, i.e., maintaining their exergy levels. The approaches are shown to permit this analysis and help evaluate what degree of disassembly makes sense and what does not.

The positive effect on recyclability is illustrated by the assessment of the level 2 disassembly, which shows an increase in material recycling rates, improved energy recovery, and a minimization of losses and/or the creation of lower-quality open-loop products from recycling. Therefore, a recommendation for additional disassembly is to separate the organics-containing sub-modules from the Cu and related metal-based modules or components to increase the concentration of valuable elements in the Cu-based module. The metal content of the organics-based fraction for energy recovery should be decreased. Harmonizing the composition of the created sub-modules with the compatibility of the metals in the different sections in the Metal Wheel is recommended. This avoids losses and the presence of harmful elements to produce high-quality closed-loop CE products. However, the very complex mixture of functional plastics suggests using their C, H, O, and other components to their best effect as chemicals as well as energy creation. Physical separation hardly makes sense.

In general, physics-based disassembly strategies should be targeted. The mixture of incompatible materials in sub-modules and/or components must be separated as much as possible into different sub-modules, if this is possible from a structural design point to view. Based on the processed MISS data, specific recommendations can be made for each module under consideration, also including exergy as a concrete decision variable, to direct sub-assemblies into the correct segments of the Metal Wheel. In this way, both the overall as well as individual material and element recycling rates can be increased, and the losses and required additional physical sorting and/or chemical upgrading (and the related requirement of primary resources/energy) can be minimized or decreased. The creation of low-valuable intermediate materials is therefore, to an extent, mitigated, as illustrated for the case of the level 2 disassembly. This process may also be considered to separate organics-containing modules, in which organics are present as well-liberated and “clean” plastics, to enhance physical separation. However, complex functionally mixed materials challenge this.

Additional disassembly changes the composition of the different car (sub-)modules. This simulation-based approach permits the optimization of the system architecture of the physical and metallurgical recycling processes, thus helping to advise policy on what metallurgical and recycling infrastructure needs to be available for optimal resource efficiency. Design for recycling is limited by, among other factors, this available infrastructure and obviously the solution chemistry to maximally recover materials and energy.

6.5.1. Disassembly and Recycling Rules and Advisory for Infotainment Unit to Optimize Recyclability

Examples of disassembly and recycling rules/advisory to optimize recyclability, as defined for one of the car electronic modules assessed (Infotainment unit), are given below:

Separate the module into sub-modules, with more comparable/compatible composition matching with the different segments in the Metal Wheel, to allow for a better recyclability of the materials into the following:
○
Cu/PCB-containing modules.
○
Fe-based modules.
○
Plastic-based modules.
○
Al-based modules (separate the Al heat-sink from the other sub-modules, hence creating an Al-based fraction to be sent to an Al processing route).
Harmonize the composition of the created sub-modules with the compatibility of the metals in the different sections in the Metal Wheel as follows:
○
b.1 Fe-based sub-modules should be further disassembled to remove modules/components containing harmful elements for Fe alloy production.
■
Remove modules or components from the Fe modules, which contain Pb, Cu, Sn, Sb, As, Bi, Ga, In, Ge, Be, S, and/or P.
○
b.2 Fe-based sub-modules should be further disassembled, if possible, to remove modules/components containing elements that are lost in the steel processing route (Au, Ag, Pd, Ru, Pt, etc.) to increase their recovery.
■
Further disassemble the “Drive” sub-module to separate Fe-based and PCB-based sub-modules/components (containing Au, Ag, Pd, Ru, and/or Pt).
○
b.3 Cu/PCB-based sub-modules should be further disassembled, if possible, to more intensively separate Fe-containing modules/components from the Cu/PCB-based sub-modules (to be sent to steel processing after disassembly), noting that the limitation is that alloy specification limits what elements may be processed in the steel cycle (see the Metal Wheel).
■
Rule A2 should be considered here with respect to the separated Fe-based parts.

6.5.2. Design for Recycling Rules and Advisory

DfR as a module of eco-design recommendations can also be defined based on the performed recycling assessment. DfR should be focused, within the limits of product functionality, on designing sub-modules and modules with their composition compatible with the different sections in the Metal Wheel. The individual recycling rates calculated in the recycling assessment quantitatively support and help choose which options in both additional disassembly and/or DfR will have the highest impact in the improvement of recyclability. Below is an example of design-specific DfR rules for the work discussed in this paper. Within the limits of design and product functionality, the following rules for the Infotainment unit can be considered:

Design (sub-)modules and modules, in which their composition is harmonized with the compatibility of the metals in the different sections in the Metal Wheel.
Avoid the use of Pb, Cu, Sn, Sb, As, Bi, Ga, In, Ge, Be, S, and/or P (and compounds) in combination with/closely linked to or integrated with Fe.
Avoid the irreversible or non-disassemble combinations and connections of Cu and linked recoverable materials (e.g., Au, Ag, Pd, Pt, etc.) with non-compatible materials/compounds/elements marked in yellow and red in the Metal Wheel for this processing route (e.g., Ta, Ti, Zr, Nb, Mg, Al, Fe, Ca, Si, etc., and compounds of these substances).
More precisely specify and detail the DfR rules by linking them up with the MISS data file that is linked to the simulation software.

Such rules can be set for each module and can be generalized. However, as stated a few times in this paper, the complexity of each module will dictate each set of recommendations. This makes simulation-based DfR so powerful as it provides the basis to (re-)calculate each situation and each redesign immediately on a physics and technology basis.

7. Definitions

Alloy: a mixture of elements in a metal defined by a specific compositional specification and functionality.

Compound: material defined in its stoichiometric chemical composition, i.e., aluminum as Al, Al₂O₃, etc.

Design for Recycling: designing a product or module with the objective of optimizing its recyclability into high-quality recycling functional material products that can find an application in possibly the same product.

Disassembly: includes dismantling and implies taking selected car modules from the entire EoL car as well as understanding if the disassembled car modules can be further selectively disassembled into smaller modules that can be channeled into the correct processing for optimal recycling.

Energy recovery: plastic compounds are used as an energy source as well as for feedstock recycling, e.g., using C and H as reductants.

Feed composition: the simulation model requires a full description of the compounds as input to the model, which must add up to 100% in weight.

Flows: all the flows of materials, solution, mixture, phases, gasses, and dust (among others) are quantified in terms of enthalpy and entropy (kWh/h) values in addition to the mass flows (both total mass flows and mass flows per compound) in kg/h or tonnes/h.

Flowsheet: A logical sequence of reactors that convert the input into among other high-quality materials, compounds, alloys, metals, building materials, and energy as well as residues and intermediates that can be ponded or used in further processes. These flowsheets are industrially realistic and economically viable for different processing routes.

Material-Centric Recycling: focusses mainly on an element, disregarding the effects of all other elements, compounds, and materials in a product.

Metal Wheel: depicts the paths of recycling materials into different processing infrastructures.

Module: This is a functional unit within a car that can perform a required task. These are selected car modules for disassembly from an EoL car (these can also be called parts, sub-parts, etc.).

Part: another name for module (see above).

Plastic compounds: The full composition of all organic molecules of C, H, O, N, Br, Cl, metals atoms, etc., in addition to fillers within the plastic. These are complex functional materials that are difficult to recycle to produce the same quality of products as the original plastic compound.

Product-Centric Recycling: this considers the full module with all materials, elements, compounds, etc., included, therefore embracing all thermochemical interactions that can occur during refining.

Product data: This is the complete composition of the product, thus covering all compounds, functional materials, alloys, plastics, etc., and their spatial position in the modules. This means aluminum can manifest itself, among other manifestations, as Al, one of the many alloys of aluminum, Al₂O₃ as an oxidized (also anodized) layer on the aluminum, hydroxide, or a filler in plastics or numerous other inorganic compounds, etc.

Reactor: a unit in which the input of material is converted to a product, energy, off gas, solution, or something similar.

Recycling rate: Within the CE paradigm, this means producing the same-quality material, alloy, metal, or compound that can be used within the different car modules. The recycling rate of each element thus implies recycling into high-quality products that can go back into the same module or product.

Recycling for circular economy: The recycling of a product within a CE implies creating the same material quality after recycling so that it can be applied in the same product.

Simulation of a process: predicting the flows of all compounds and phases throughout the complete flowsheet on a thermochemical, Gibbs free/energy, and kinetic basis, including the functional detail of the different reactor types in the system, which are dictated by mass and heat transfer as well as fluid flow.

Sub-modules: specific modules on the car module that can possibly be disassembled into smaller modules, removed, and sent to more dedicated processing to maximize the recovery of elements, compounds, alloys, energy, etc.

TREASURE: An EC-funded project www.treasureproject.eu [29] (accessed on 13 October 2024).

Author Contributions

Conceptualization, A.v.S. and M.A.R.; methodology, A.v.S. and M.A.R.; software, A.v.S. and M.A.R.; validation, A.v.S. and M.A.R.; formal analysis, A.v.S. and M.A.R.; investigation, A.v.S. and M.A.R.; resources, A.v.S. and M.A.R.; data curation, A.v.S. and M.A.R.; writing—original draft preparation, A.v.S. and M.A.R.; writing—review and editing, A.v.S. and M.A.R.; visualization, A.v.S. and M.A.R.; project administration, A.v.S.; funding acquisition, A.v.S. All authors have read and agreed to the published version of the manuscript.

Funding

The work and research as presented in this paper was funded by the European Union in a European Union’s Horizon 2020 research and innovation program under grant agreement No 101003587 (EU Treasure project). The views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or European Health and Digital Executive Agency (HADEA). Neither the European Union nor the European Health and Digital Executive Agency (HADEA) can be held responsible for them.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

This paper provides a considerable amount of data in the various graphs and tables. These have been generated with a process simulation model based on Gibbs and reaction equations, that have been documented elsewhere and will not be repeated here.

Conflicts of Interest

Author Antoinette van Schaik was employed by MARAS B.V. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Abbreviations

1LT	First law of thermodynamics
2LT	Second law of thermodynamics
AI	Artificial intelligence
BAT	Best available technology
BoL	Beginning of Life
BoM	Bill of materials
CAS number	Chemical Abstracts Service number
CE	Circular economy
CRMs	Critical Raw Materials
DfR	Design for Recycling
DRI	Direct Reduced Iron
EAF	Electric Arc Furnace
EC	European Commission
ELV	End-of-Life Vehicle
EoL	End of Life
FMD	Full material declaration
HSC Sim 10	Process simulation software by www.metso.com
kW	Kilowatt—unit of energy and exergy flow kW/h (or MJ/h)
TREASURE	EU H2020 project www.treasure.eu
MFA	Material Flow Analysis
MISS	Material Information Systems
LCA	Life Cycle Assessment
RI	Recycling Index
RE	Resource efficiency
TBRC	Top Blown Rotary Convertor
TSL	Top Submerged Lance bath smelter
UNEP	United Nations Environmental Programme
WEEE	Waste Electric and Electronic Equipment

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Figure 8. Major materials of the Infotainment unit of Leon II (simplified classification due to confidentiality reasons).

Figure 9. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route, steel processing and energy recovery)—Infotainment unit of Leon II. Compare this with Figure 12 for the Leon III unit.

Figure 10. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product (in the other two routes, no closed-loop high-quality product is produced directly from the route).

Figure 11. Major material classification of Infotainment unit of Leon III (simplified classification due to confidentiality reasons).

Figure 12. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route, steel processing and energy recovery)—Infotainment unit of Leon III. Compare this to Figure 9 for the Leon II unit.

Figure 15. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route and energy recovery)—Combi-instrument of Leon II.

Figure 16. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product.

Figure 18. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route and energy recovery)—Combi-instrument of Leon III.

Figure 19. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product.

Figure 20. Major material classification of the Combi-instrument of Ibiza IV (simplified classification due to confidentiality reasons).

Figure 21. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route and energy recovery)—Combi-instrument of Ibiza IV.

Figure 22. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product.

Figure 23. Major materials classification of the Additional Brake Light of Leon II, which is a simplified classification due to confidentiality reasons (values with 0 are below 2 decimals of accuracy).

Figure 24. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route and energy recovery)—Additional Brake Light of Leon II.

Figure 25. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product (note that the elements presented with gray bullets are not present in the car module).

Figure 26. Major materials classification of the Additional Brake Light of Leon III (values with 0 are below 2 decimal of % accuracy).

Figure 27. Recycling Index for closed- and open-loop CE products and energy recovery because of the processing of the car module in different recycling routes (Cu processing route and energy recovery)—Additional Brake Light of Leon III.

Figure 28. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the car module in the Cu processing route for the valuable metal product.

Figure 29. Major composing materials of the sub-modules of the Combi-instrument of Leon II with composition in main material classes of (a) the plastic modules (summed), (b) the PCB modules (summed), and (c) ferrous-based module, a simplified classification due to confidentiality reasons. (values with 0 are below 2 decimals %).

Figure 30. Recycling Index for closed- and open-loop CE products and energy recovery as a result of the processing of the car sub-module in the most suitable recycling routes (Cu processing route for the recovery of the PCB modules, steel processing for the recovery of the ferrous module, and energy recovery for the processing of the plastics/organics modules from the Combi-instrument of Leon II (all results are achieved at the same time; this is different from the options presented in Figure 15).

Figure 31. Recycling Index for closed- and open-loop CE products and energy recovery of the total Combi-instrument as a result of the processing of the car sub-module in the most suitable recycling routes (Cu processing route for the recovery of the PCB modules, steel processing for the recovery of the ferrous module, and energy recovery for the processing of the plastics/organics modules.

Figure 32. Material Recycling Flower showing recycling rates for a range of selected elements for the recycling of the (a) PCB modules of the Combi-instrument of Leon II in the Cu processing route for the valuable metal product and (b) the ferrous module of the Combi-instrument in the steel processing route.

Figure 33. Exergy flows (kW) [36] for the PCB modules of the Combi-instrument of Leon II in the Cu processing route for the valuable metal product. Compare this figure to Figure 3, that shows the respective tonnes/h flows, underlining the thermochemical basis of the simulation model.

Table 2. A small selection of environmental (LCA) indicators, which can be derived from the recycling process simulation models as HSC Sim is directly linked to environmental assessment- here shown only as a general example.

Environmental Indicators	Amount	Unit
Cu processing route
Scope 1 GWP	0.43	kg CO₂/kg Module
Scope 1 AP (SO_x + NO_x)	Low	kg SO_x-eq/kg Module
Energy recovery route
Scope 1 GWP	0.42	kg CO₂/kg Module
Scope 1 AP (SO_x + NO_x)	Low	kg SO_x-eq/kg Module

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van Schaik, A.; Reuter, M.A. Simulation-Based Design for Recycling of Car Electronic Modules as a Function of Disassembly Strategies. Sustainability 2024, 16, 9048. https://doi.org/10.3390/su16209048

AMA Style

van Schaik A, Reuter MA. Simulation-Based Design for Recycling of Car Electronic Modules as a Function of Disassembly Strategies. Sustainability. 2024; 16(20):9048. https://doi.org/10.3390/su16209048

Chicago/Turabian Style

van Schaik, Antoinette, and Markus A. Reuter. 2024. "Simulation-Based Design for Recycling of Car Electronic Modules as a Function of Disassembly Strategies" Sustainability 16, no. 20: 9048. https://doi.org/10.3390/su16209048

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Simulation-Based Design for Recycling of Car Electronic Modules as a Function of Disassembly Strategies

Abstract

1. Introduction

2. The Approach: Simulation-Based Recycling Assessment and DfR

2.1. The Nexus of Processes Simulation and CE—Using Thermodynamics for Maintaining Quality of Materials and Energy Flows into and out of a Product

2.2. KPIs and Information from Simulation Models

2.3. Design for Recycling and Design for Circularity

2.4. Simulation-Based LCA

3. The Data: Data Processing of Car Module Data and Transforming to Compatibility for Simulation

3.1. Data Analyses and Processing

3.2. Car Modules Included in the Recyclability Assessment

3.3. Results of Data Analyses and Processing

3.3.1. Classification of Organic Compounds

3.3.2. Full Compositional Build-Up of the Car Modules—Results of the Data Processing

3.4. Automation of Data Processing for TREASURE Platform and Digitalization for CE Assessment

4. Recyclability Assessment and Data for Modules

4.1. Recycling Process Simulation Model

4.2. Recycling Assessment of Car Modules and Selection of Most Suitable Processing Routes

5. Results of Recycling Assessment

5.1. Model Definitions and Set Up for Recycling Assessment of Car Modules Selected for Disassembly

5.2. Assessment of Different Recycling Routes for Recycling of Car Modules and Sub-Modules

5.3. Results of Recycling Assessment Different Car Modules (Level 1 Disassembly)

5.3.1. Results of Recycling Assessment Infotainment Unit of Leon II

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of Infotainment Unit from Leon II

Conclusions

5.3.2. Results of Recycling Assessment Infotainment Unit of Leon III

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of Infotainment Unit from Leon III

Conclusions

5.3.3. Results of Recycling Assessment Combi-Instrument of Leon II

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of the Combi-Instrument from Leon II

Conclusions

5.3.4. Results of Recycling Assessment of Combi-Instrument Leon III

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of the Combi-Instrument from Leon III

Conclusions

5.3.5. Results of Recycling Assessment of Combi-Instrument Ibiza IV

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of the Combi-Instrument from Ibiza IV

Conclusions

5.3.6. Results of Recycling Assessment of Additional Brake Light Leon II (Mirror/Lighting)

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of the Additional Brake Light of Leon II

Conclusions

5.3.7. Results of Recycling Assessment of Additional Brake Light of Leon III (Mirror/Lighting)

Composition of Car Module

Overall/Total Recycling Rates

Individual Material Recycling Rates

Discussion of Results of Recycling Processing of the Additional Brake Light of Leon III

Conclusions

5.4. Results of Recycling Assessment After Additional Disassembly (Level 2) of the Combi-Instrument of Leon II

5.4.1. Composition of the Sub-Modules of the Combi-Instrument of Leon II

5.4.2. Overall/Total Recycling Rates

5.4.3. Individual Material Recycling Rates

5.4.4. Discussion of Results of Recycling Processing of the Car Sub-Modules After Additional Disassembly (Level 2) of the Combi-Instrument of Leon II

5.4.5. Conclusions on the Effect of Additional Disassembly on Recycling Performance

5.5. Results of Recycling Exergy Assessment of the Combi-Instrument of Leon II

6. Conclusions and Recommendations

6.1. Recycling System Modelling

6.2. Data Processing and Automation

6.3. KPIs

6.4. Recyclability Results and Most Suitable Recycling Routes for Processing of Car Modules

6.5. Recommendations on Additional Disassembly and DfR (Eco Design)

6.5.1. Disassembly and Recycling Rules and Advisory for Infotainment Unit to Optimize Recyclability

6.5.2. Design for Recycling Rules and Advisory