The transition towards a circular economy is being increasingly envisaged in Europe. Increased utilisation of secondary construction aggregates poses a great opportunity in this regard given its potential to avoid waste disposal, natural resource extraction, and reduce costs. Nevertheless, the Swedish construction aggregates market is dominantly characterised by primary aggregates utilisation. This study employs a qualitative approach to analyse the Swedish construction aggregates market from the user perspective in order to identify the challenges of increased utilisation of secondary aggregates. The dominant and systematic utilisation of primary aggregates is chiefly driven by market processes allowing economic advantages and convenience for the users in doing so, whereas the situational and non-systematic utilisation of secondary aggregates is opportunistically driven by different actors in order to seize opportunities such as avoided costs and improved environmental performance. The realisation of increased secondary aggregates utilisation needs to be first facilitated via changes to the institutional structure that makes such materials a priority issue for the supply chain actors, which necessitates national-level policy interventions and supply chain actor collaborations. Second, the competitiveness of secondary aggregates needs to be lifted to a comparable state to that of primary aggregates, which necessitates the development of specific sectoral application standards and vertical integration of secondary aggregates supply by construction corporations.

In the context of circular economy in the European region the role of the recycling industry has become ever important. Shredder fines (or fines) is a heterogeneous fine-granular production residue of the shredding industry, and is currently disposed of. Shredder fines presents a disposal problem and incurs handling costs to the shredding industry. More importantly, its disposal reduces the resources efficiency of our society. This thesis aims to contribute systems-oriented knowledge to facilitate the valorisation of shredder fines in the Swedish context. In doing so, it contributes to two knowledge. Knowledge area one portrays the current picture concerning fines management in terms of the underlying factors of the current practice of fines management and the market prospects for secondary construction aggregates. Knowledge area two showcases the potential approach to initiate process development in terms of assessments of the resource potential of fines and the environmental impact of fines-valorisation. 

The findings of knowledge area one show that the studied shredding company is more inclined towards continuing on the current disposal-oriented management of fines. That is because of both incentives for utilising fines as landfill cover materials and disincentives for valorising fines, created by various policy, market, and organisational factors. On the other hand, a significant need exists to improve the prospects of secondary aggregates in the construction aggregates market. Currently, the market is chiefly characterised by processes and underlying structures that sustain dominant primary aggregates utilisation, whereas secondary aggregates utilisation is situational and driven by different supply chain actors due to different individual reasons.

The findings of knowledge area two show that process development for fines valorisation has several technical and environmental challenges. The resource potential assessment of the fines shows that the initial technical feasibility of fines valorisation is considerable, however different resource recovery strategies would require different levels of processes for upgrading and resource recovery. The ex-ante life cycle assessment of fines valorisation shows that potential fines valorisation is environmentally more promising compared to landfill-related disposal, however, different resource recovery strategies would create different levels of environmental impacts and present different needs for improvements.

Facilitating fines valorisation calls for different measures on the institution and actor levels. Drastic policy measures are required to remove the incentives for the disposal of the material and compel shredding companies to seek valorisation alternatives. In order to ensure long-term sustenance of fines valorisation, fines-derived secondary raw materials need secure outlets and clear market and regulatory playing rules for their generation and application. Additionally, environmentally feasible and cost effective upgrading and resource recovery processes have to be developed.

The origin of circular economy is grounded in restoring the environmental balance and reducing the throughput of natural resources in anthropogenic systems. Nevertheless, the current conceptualisation of circular economy is predominantly focusing on the economic progress, which somewhat promotes “business as usual”. This thesis attempts to reinstate the original resource conservation idea of circular economy in relation to heterogeneous industrial residue valorisation.

In concomitance with the growing developments around the circular economy concept in the region, the resource recovery and recycling of industrial production residues is increasingly being envisaged in the European Union and its member states. The role of the recycling industry has become ever important in this context. The shredding industry is based on shredding discarded products such as end-of-life vehicles, and municipal white goods, and subsequent retrieval of (primarily) metals. Shredder fines (or fines) is a heterogeneous fine-granular production residue of this industry, which is currently disposed of. Shredder fines presents, and will continue to do so in the foreseeable future, several challenges that need to be addressed. It creates a disposal problem given the shrinking landfill availability and incurs handling costs to the shredding industry. Furthermore, it reduces our resources efficiency in general.

This thesis aims to contribute knowledge on the challenges of facilitating the valorisation of shredder fines in the context of Sweden. In doing so, the current situation concerning fines and its management was investigated by addressing the research questions; 1) What is the resource potential of fines generated at the studied shredding plant, and 2) Why is the current disposal-oriented management of shredder fines sustained in Sweden. There, a systems perspective was employed, where the research questions were addressed on the material, actor, and institution levels, based on three scientific articles, which are appended.

The studied material carries a certain amount of potentially recoverable resources, nevertheless shows a significant need for upgrading pertaining to the user requirements and regulatory standards of different recovery applications. The full recovery of fines requires integrated processes that could simultaneously harness these resource opportunities and resolve the material constraints. When it comes to the current practice of managing fines in Sweden, the utilisation in landfill covering offers the shredding companies a secure outlet for the material, given it is a well-established practice that has evolved over decades of operations and there is still a significant demand for landfill cover materials. Additionally, it provides shredding companies with a legislatively-compliant low-cost disposal option for managing fines. On the other hand, the complex materiality, lack of marketability of secondary raw materials (SRMs), and unfavourable governmental regulation of waste recovery create strategic disincentives for shredding companies in opting for fines valorisation.

Fines valorisation calls for change in the well-established current practice of utilising the material in landfill covering. Thus, drastic policy measures such as phasing out landfilling and mandating resource recovery and recycling of fines are required to remove the incentives for fines disposal and compel the shredding industry to seek valorisation alternatives for its management. In order to ensure long-term sustenance, applications based on fines valorisation need favourable and more predictable circumstances and settings on different societal levels. There, secure outlets for potential fines-derived SRMs is one of the essential elements. Governmental interventions to create demand and alleviate valorisation investments via market and financial instruments play a significant role in that regard. The other primary requirement to facilitate fines valorisation in the long term is to set clear market and regulatory playing rules. Established supply and demand structures would enable clear pricing mechanisms for fines-derived SRMs and accurate economic assessments of fines valorisation, thus reducing the investment risk for shredding companies. On the other hand, clear regulatory standards and favourable regulatory practices would reduce the uncertainty of the realisation of valorisation applications and gain trust among actors.

The recycling-industry residue called shredder fines (fines) presents a disposal problem,incurs handling costs, and reduces resource efficiency in general. This study aims to identify thechallenges of facilitating fines valorisation in the Swedish context. Hence, the shredding companyperspective of the underlying factors that sustain the current practice of fines management isestablished by studying the case of a specific shredding company using semi-structured interviews.Utilisation in landfill covering offers the company a secure outlet and a legislatively-compliant lowcostdisposal option for fines. Additionally, lack of specific regulatory standards, unfavourableregulation of waste reutilisation, and lack of market demand for secondary raw materials (SRMs)create disincentives to develop valorisation options. Also, the lack of corporate-level focus on theissue has resulted in a lack of organising for and capacities to improve the handling of the material.Initiating fines valorisation needs to challenge these prevailing circumstances and thus necessitatesgovernmental interventions. Simultaneously, favourable conditions for SRM utilisation are needed;that is, established outlets for fines-derived SRMs and clear regulatory and market playing rulesthat reduce uncertainty and investment risk of developing tailored processes for upgrading andresource recovery need to be available.

Millions of tonnes of shredder fines are generated and disposed of globally, despite compelling reasons for its recovery. The absence of a review of previous literature, however, makes it difficult to understand the underlying reasons for this. Thus, this study attempts to investigate and assess what, to what extent, and in what ways shredder fines have been addressed in previous research. In doing so, guidelines are drawn for future research to facilitate the valorisation (upgrading and recovery) of shredder fines. Previous research concerning shredder fines was identified with respect to three main research topics. The material characterisation studies are predominantly confined to the occurrence of metals due to their recovery and contamination potential. The process development studies have often undertaken narrowly conceived objectives of addressing one resource opportunity or contamination problem at a time. Consequently, the full recovery (the retrieval of valuable resources and the bulk-utilisation as substitute material) potential of shredder fines has been largely overlooked. The main limitation of policy and regulation studies is the absence of in-depth knowledge on the implications of governmental waste- and resource-policies (macro-level) on actors’ incentives and capacities (micro-level) for fines valorisation, which is necessary to understand the marketability of fines-derived resources. Undertaking a systems perspective is the key to recognising not only the different aspects within the individual research topics but also the inter-relations between them. It also facilitates the internalisation of the inter-relations into topical research.

The lack of process development based on a comprehensive understanding of the material characteristics and the marketability of recoverables is the primary reason why the valorisation of shredder fines has not been realised in practice. In response, a systematic approach was undertaken consisting of 1) strategic sampling and material characterisation, 2) establishing gate and regulatory requirements of potential valorisation applications, and 3) initial feasibility assessment of the selected applications, to guide future research.

The material was sampled over ten weeks in order to obtain both average values and variations of the physical and chemical composition. Thus weekly, primary fractions and sieved fractions ZA (7.10–5.00 mm), ZB (5.00–3.35 mm), ZC (3.35–2.00 mm), ZD (2.00–0.25 mm), and ZE (0.25–0.063 mm) were prepared, and analysed, and benchmarked against the requirements pertaining to five potential applications. The mercury and aluminium concentrations are the biggest challenge in copper smelting and only ZA and ZB show significant potential. Energy recovery is limited to ZA, ZB, and ZC, provided the chlorine and metals concentrations are decreased. Regarding the recovery as bulk-material in construction, the reduction of the metal content would likely be a pre-requisite.

The utilisation of fines in the individual applications would either leave a significant amount of fines un-valorised or overlook the recovery of valuable resources. The upgrading of the material to suit the different applications would also require addressing multiple material constraints simultaneously. Therefore, realising the full resource potential of shredder fines would require the integration of different upgrading and recovery processes.

Shredder fines is a residue of the shredding industry and is currently landfilled or used as landfill cover in Sweden. Throughout the time, the heterogeneity and small particle size have rendered resource recovery and recycling of it challenging. In spite of that, European policies envisioning circular economy, in concomitance with stringent resource recovery requirements and increased landfill taxes are challenging the current disposal practices of the shredding industry. As an attempt to address this issue, the present study has developed a systematic approach for performing an initial assessment of the feasibility of several selected mainstream applications for valorisation of shredder fines.

First, sampling of shredder fines from a major shredding plant was obtained twice a week over a 10 weeks period. The main focus of the sampling program was to encompass the variation in the material’s physical and chemical composition. The two samples from each week were then mixed and divided into six subsamples. That is, one original fraction and five size fractions; ZA (7.10-5.00 mm), ZB (5.00-3.35 mm), ZC (3.35-2.00 mm), ZD (2.00-0.25 mm), and ZE (0.25-0.063 mm). These sub-samples were subsequently sent for laboratory analysis for characterisation of contaminants, potentially valuable metals and energy recovery related properties. Second, three potential main stream applications for shredder fines were identified based on existing research on similar industrial residues (e.g. municipal waste incineration bottom ash) and current practices of the Swedish shredding industry. The selected applications are; Smelting for copper, Energy recovery in cement kilns and municipal solid waste incinerators, and Substitution of aggregates in concrete making and road construction. Third, the gate requirements of potential users and legislative requirements with regards to the identified applications were established, and the characteristics of shredder fines were benchmarked against them.

As far as copper smelting is concerned, the presence of high concentrations of lead and chromium is the biggest challenge. Otherwise, the fractions; ZA, ZB, and ZD show some potential due to manageable concentrations of arsenic, cadmium, and mercury. Concerning energy recovery, the calorific value apparently narrows down the options to municipal waste incinerators. There, the chlorine concentration only allows utilisation of the ZC fraction whereas heavy metal concentrations are too high with regards to all the fractions. With regards to the use as substitute material in construction, legislative requirements in Sweden for total content and leachate content of metals are too strict for shredder fines.

In conclusion, the benchmarking reveals the need for prior upgrading of shredder fines with respect to the different applications. Thus, integrated upgrading processes that could handle the complexity of the material in terms of contaminants and valuable recoverables is needed in order to achieve holistic valorisation of the material.

Residue products often pose a huge challenge to material recycling industry. Especially heterogenic and fine granular residues. It increases the cost and reduces the efficiency of material separation and recovery. Currently, the most common practice is to landfill such residue products. However, decreasing availability of landfills, increasing landfill costs, and new policy instruments require higher rates of resource recovery. In spite of that, business initiatives for recovering secondary raw material from residue products are often deterred by stringent environmental legislation emphasizing human toxicity concerns. Shredding industry plays a huge role in the context of circular economy via recycling important waste streams such as end-oflife vehicles (ELVs), municipal white goods, construction and demolition waste, and different industrial wastes. The core business model of industrial shredding is driven by recovering different metals while a variety of residue products including plastics, rubber, foam, wood, glass, and sand are generated. Shredder fine residue (also called shredder fines) is a fine granular residue product with intrinsic heterogeneity, which is produced by the shredding industry. A share of 15-20% of the input would end up as shredder fines in a typical plant.

The overall aim of this study is to draw technical, market and regulatory boundary conditions for improved material recovery from shredder fines. Thereby to build a framework of principal guidelines to support systematic identification, development, and evaluation of different valorization options for shredder fines. The outcome of this study is also envisioned to provide generic conclusions to the valorization of heterogenic residue products in general.

The study is performed in collaboration with a major shredding company in Sweden. The methodology reflects the Swedish context and consists of two phases. During the initial phase, firstly, the overall shredding industry structure of Sweden is studied to understand the governing regulatory framework, level of competition, and the scale of operation. Secondly, the collaborating company is studied to gain knowledge on technical feasibility of implementing recovery processes, economic, business and market aspects, and implications of national and local legislation, from the shredding company perspective. Empirical methods such as interviews and study of documentation are used in this phase.

During the second phase, detailed material and elemental characterization tests are performed on shredder fine samples. Thereby the distribution of basic elements, metals, heating value, and ash, in shredder fines as well as across different size fractions of shredder fines is established. The results are compared and contrasted against literature values. An extensive survey is also carried out to identify potential users for different materials which are possibly recoverable from shredder fines. Such potential users are then mapped against materials. Leaching tests are also performed to assess the mobility of heavy metals and thereby the potential environmental risk and human toxicity.

As the main contribution of this study, knowledge is developed and synthesized, boundary conditions are set, and principal guidelines of general relevance are drawn in order to facilitate improved valorization of fine granular residue products.