Challenges and Opportunities for the Development of Urban Mining in Brazil

Abstract

This article examines urban mining in Brazil, highlighting its unique context compared to other regions. While European Union focuses on critical metal supply and advanced Waste Electrical and Electronic Equipment (WEEE) legislation and circular economy, Brazil’s urban mining is primarily driven by waste management and social inclusion. The current investigation was underpinned by the PRISMA extension for Scoping Reviews (PRISMA-ScR framework), using targeted searches on the Web of Science platform for technological processes and the Brazilian scenario, complemented by an analysis of legislative evolution and a Critical Discourse Analysis of national policies. The results indicate that, despite advanced legislation, significant gaps exist between discourse and practice, highlighting the need for technological appropriation, specific public policies that incentivize reverse logistics and the integration of the informal sector, and overcoming infrastructural challenges. It concludes that Brazil has a unique opportunity to develop an urban mining model that pioneeringly integrates environmental sustainability, technological innovation, and social inclusion, demanding coordinated efforts to overcome existing barriers.

1. Introduction

Urban mining, conceived as a circular economy strategy, encompasses various concepts that complement each other by aiming to transform waste into valuable secondary resources. Attention towards this type of mining has been growing in discussions about secondary raw materials, although its application in developing countries is often limited by local resources, technology, and ineffective legislation on electronic waste (e-waste) [1].

Kazançoglu et al. [2] describe urban mining as a management approach that aids the supply of secondary raw materials through the recycling of precious metals, contributing to improved consumption patterns and decreased resource use. Ghisellini et al. [3] expand on this idea, defining urban mining as a process (encompassing collection, separation, sorting, and processing) at the city level for waste streams such as Construction and Demolition Waste (CDW) and Waste Electrical and Electronic Equipment (WEEE), aiming for their return to a new production cycle.

These concepts complement each other by highlighting that urban mining is an activity embedded within the context of the circular economy, with the main objective of recovering resources from waste, thereby decreasing the reliance on virgin raw materials. They differ, on the other hand, in the scope of the waste considered and the level of detail of the process. While some authors focus primarily on e-waste, others include a broader range of urban waste, such as CDW. Although considered for the development of urban mining, CDW is not included in the discussions in the discussions of this article.

In the context of the circular economy, urban mining operationalizes the principle of material circulation, transforming what would be discarded into a new source of resources. Fatimah et al. [4] state that efforts to overcome the e-waste problem exist, and urban mining is an essential component of these efforts. Ouro-Salim [5] also emphasizes the synergy between urban mining and the circular economy, highlighting that the former serves as a critical mechanism to realize the principles of the latter and minimize environmental impacts.

In the realm of sustainability, urban mining presents itself as a practice with the potential to generate positive impacts in various dimensions. Environmentally, it contributes to the reduction of pollution associated with the inadequate disposal of hazardous waste, such as those present in e-waste [1,5,6,7,8]. Economically, it can generate new business opportunities and green jobs, in addition to reducing costs for industries by providing secondary raw materials [1,9,10]. Socially, it can promote the formalization of the informal recycling sector and improve the working conditions of those involved [3,10].

Urban mining of e-waste is a new frontier to be explored in Brazil, with the potential for economic valorization and waste minimization [9]. Its successful implementation can play important roles in promoting several Sustainable Development Goals (SDGs), including sustainable cities and communities (SDG 11) and responsible consumption and production (SDG 12) [4].

When contrasting the approaches to urban mining in different global regions, such as Brazil and the European continent, it is noticeable that, although a common goal of sustainability may be shared, the urgency and motivators manifest in distinct ways. Specifically, the European Union (EU) presents a case of advanced regulatory development for WEEE and circular economy, though implementation and focus can vary.

The European Union (EU), in particular, driven by concerns over resource scarcity and a commitment to environmental leadership, has developed strong environmental regulations and ambitions to lead the transition to a circular economy. This positions urban mining as a central strategy to ensure access to essential materials and reduce import dependency. Baldé et al. [11] highlight that European countries, especially those within the EU, are often cited as examples in legislating and managing e-waste. The growing consumer awareness and the pressure for responsible business practices also drive this activity as a strategic priority for industrial competitiveness and security of supply within this bloc and other developed European nations.

On the other hand, Brazil, possessing vast mineral reserves, faces the challenge of reconciling economic development with the effective application of its environmental legislation, which often presents gaps and enforcement challenges. Although the country has abundant mineral resources, the uncontrolled exploitation and environmental impacts associated with conventional mining generate considerable social and environmental costs. In this context, urban mining in Brazil reveals itself as a necessity to promote sustainable development, reduce social inequalities, and protect its vast natural heritage.

A critical analysis reveals that the different socioeconomic and regulatory contexts shape the implementation of urban mining in Europe and Brazil. While Europe invests in advanced recycling technologies and the creation of value chains for recovered materials, aiming to strengthen its strategic autonomy and reduce its ecological footprint, Brazil still faces significant challenges. Among these challenges are the public’s lack of knowledge about the correct destination of WEEE, the informality in the recycling chain, the lack of an official database on the generation and flows of WEEE, and the difficulties related to the traceability of this waste [10].

Additionally, Brazil’s continental dimensions and the concentration of recyclers in the South and Southeast regions of the country, coupled with the scarcity of processing units for precious metals, increase logistical costs and may increase greenhouse gas emissions resulting from transportation, including for export. The lack of a specific and unified taxation policy for the sector also generates legal uncertainty and can discourage urban mining entrepreneurs. In contrast, the European Union, with its more developed infrastructure and cohesive policies regarding the circular economy and waste management, presents a more favorable scenario for the expansion of urban mining on a large scale. However, it is important to note that even within the EU, the effectiveness and implementation of these policies can vary, with challenges in meeting collection and recycling targets remaining [11].

Considering the presented panorama, this article proposes to analyze the challenges and opportunities for the development of urban mining in Brazil, focusing on the dimensions of knowledge production, technological appropriation, and the effectiveness of current and necessary legislation to drive this activity. Through the investigation of these pillars, this analysis seeks to contribute scientifically to a deeper understanding of Brazil’s specific conditions, offering subsidies for future research and for the formulation of public policies that can effectively promote urban mining as a strategy for sustainability and the utilization of secondary resources in the country.

Despite growing global attention to urban mining, a comprehensive understanding of its development within the unique Brazilian context—marked by distinct socioeconomic drivers, technological capacities, and regulatory challenges compared to scenarios like the European one—remains limited. Specifically, while extensive research exists on urban mining in developed nations, there is a notable gap in the literature concerning its specific challenges and opportunities in developing countries such as Brazil, which possesses vast mineral reserves but faces significant hurdles in reconciling economic development with effective environmental legislation. This study addresses this critical research gap by systematically analyzing the dimensions of knowledge production, technological appropriation, and legislative effectiveness in Brazil, moving beyond the implied need for urban mining to a direct examination of its operationalization and support systems within a unique national context.

Therefore, this scoping review seeks to bridge this understanding gap by systematically investigating the current state and future perspectives of urban mining in Brazil through a multi-dimensional lens. Specifically, this study is guided by the following research questions:

• What is the current state of knowledge production regarding urban mining in Brazil, and how does it compare with international trends?
• What are the main technological routes being explored or required for urban mining in Brazil, and what are the challenges for their effective appropriation in the national context?
• To what extent is the current Brazilian legislation effective in driving urban mining, and what are the main legal and regulatory obstacles that need to be overcome?
• How do the challenges and opportunities for urban mining in Brazil compare with those observed in the European context, considering their distinct socioeconomic and environmental drivers?

2. Methodology

This study was conducted as a comprehensive scoping review to analyze the challenges and opportunities for the development of urban mining in Brazil, focusing on the dimensions of knowledge production, technological appropriation, and the effectiveness of legislation. The reporting of this review was guided by the principles outlined in the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) extension for Scoping Reviews (PRISMA-ScR) Checklist [12].

2.1. Eligibility Criteria (PRISMA Item 6)

Sources of evidence included original research articles and review articles. Priority was given to publications from the last five years (approximately 2020–2025), with consideration for seminal works up to 10 years old to ensure a robust overview of the current panorama while also identifying research gaps and avoiding duplications. Articles were primarily sought in English and Portuguese. The focus was on studies directly addressing urban mining concepts, processes, challenges, opportunities, and legislative aspects pertinent to Brazil or offering comparative insights. Studies that did not clearly align with these themes were excluded.

2.2. Information Sources and Search Strategy (PRISMA Items 7 and 8)

The primary information source for scientific literature was the Web of Science (WoS) platform. The most recent search was conducted in March 2025. The search strategy involved specific term combinations designed to capture different facets of urban mining relevant to the study objectives.

For the analysis of processes and technologies employed in urban mining (Section 4), combined searches were performed for the term “urban mining” with the main chemical recovery processes: “hydrometallurgy”, “pyrometallurgy”, and “biohydrometallurgy”. To examine knowledge production and technological appropriation in Brazil (Section 6), the term “urban mining” was used, filtering the results by Countries/Regions: “Brazil”. For all situations, we apply the filter by document type in order to obtain only original research articles and review articles.

Table 1. Quantification of searches versus keywords used.

Keywords	Records Obtained 1
“urban mining” and “hydrometallurgy”	27
“urban mining” and “pyrometallurgy”	9
“urban mining” and “biohydrometallurgy”	10
“urban mining” and filtering the results by Countries/Regions: “Brazil”	41

¹ Search Period = the last search was conducted in March 2025.

summarizes the results for the main searches used:

Additionally, the methodological approach for the analysis of the legal dimension (Section 7) involved a review of legislative documents and policies pertinent to Brazil and the European Union. This analysis focused on providing an overview of the evolution of legislation on solid waste, with a comparison between Brazil [13,14,15,16] and the European Union [17,18,19,20,21], dedicating special attention to Waste Electrical and Electronic Equipment (WEEE) as a central raw material for urban mining. The National Solid Waste Policy [22] and its subsequent decrees [23,24,25,26] were detailed, explaining concepts such as shared responsibility and reverse logistics.

Further relevant sources, in addition to those initially identified by the term combinations (Extra sources), were included whenever they were considered relevant to enrich the discussion and provide a more comprehensive understanding of the theme.

2.3. Selection of Sources of Evidence (PRISMA Item 9)

The selection process involved an initial screening of titles and abstracts of the articles retrieved from the database searches based on their relevance to the review’s objectives and the eligibility criteria. Articles clearly outside the scope were excluded during this initial phase. Full-text articles deemed potentially relevant were then assessed for eligibility through a critical reading based on the criteria outlined above. This assessment focused on confirming the direct relevance and contribution to the specific analytical dimensions of this review (knowledge production, technological appropriation, legislative aspects, processes, and the Brazilian context). Articles that did not meet the inclusion criteria after full-text review were excluded, and the reasons for exclusion were noted.

To transparently illustrate the systematic selection of studies included in this review, a PRISMA flow diagram (Figure 1) has been rigorously adapted and presented. This diagram meticulously details the number of records identified from databases and other sources, the quantity screened, those assessed for eligibility, and ultimately, the total number of studies included. Furthermore, the diagram explicitly outlines the reasons for exclusion at each stage of the review process, thereby enhancing the reproducibility and clarity of our methodology in accordance with PRISMA-SCR guidelines. This comprehensive visual representation ensures a thorough understanding of the evidence selection process and addresses the need for adequate presentation and discussion of the flow of information through the different phases of this scoping review.

2.4. Data Charting and Synthesis of Results (PRISMA Items 10, 11, 13)

Data charting focused on identifying key information from the included studies relevant to the review questions and objectives. Variables for which data were sought included the study’s focus (e.g., specific urban mining process, type of waste, geographical scope, policy analysis), methodology of the primary study, key findings related to challenges and opportunities, technological approaches discussed, and legislative aspects analyzed.

The data were synthesized narratively and thematically, rather than through a quantitative meta-analysis, which is characteristic of scoping reviews. The findings were grouped and presented within the corresponding sections of this review, addressing the dimensions of knowledge production, technological appropriation, and the legal framework for urban mining in Brazil, often contrasting with the European context.

For the legal dimension (Section 7), a qualitative Critical Discourse Analysis (CDA), based mainly on the theoretical-methodological proposal of Norman Fairclough [27], was employed to analyze Brazilian policies related to WEEE. This analysis sought to identify the existing gaps between the official discourse and the operational reality, the lack of clarity and ambiguities in the definition of responsibilities, as well as the practical difficulties in the implementation of legal guidelines. The application of CDA allowed a more in-depth evaluation of the effectiveness of the current legislation, highlighting challenges such as the informality of the sector, the insufficient awareness of the population, and the need for investment in infrastructure, contributing directly to the analysis proposed in the article.

Extra sources, although not strictly part of a systematic database search, were included when they provided important context or complementary information not found in a systematic way within the search results. Information from these sources was integrated into the narrative synthesis where relevant.

3. Fundamentals of Urban Mining

Urban mining, which consists of the recovery of valuable materials and the coordination of materials, information, and services that enable the recovery of value from industrial and urban activities, can be understood as the set of processes and activities related to the production of secondary raw materials from Urban Solid Waste (USW) [28]. The term is applied exclusively to the recovery of secondary raw materials from waste under the concept of the 3Rs (reduce, reuse, and recycle), with the premise that valuable materials can be recovered from waste in a manner analogous to traditional mining, producing high-value and sustainable secondary raw materials [9].

The main components of urban mining (Figure 2) involve the collection and dismantling of waste; pre-treatment, which includes steps such as size reduction, grinding, and separation of metallic and non-metallic fractions; and processing for the recovery of valuable materials, using physical, chemical, or biological methods [29].

Various types of urban waste can be used as raw materials in urban mining, including: Waste Electrical and Electronic Equipment (WEEE) or e-waste, which has high potential due to its diversity and concentration of metals—this waste contains precious metals (Au, Ag), base metals (Cu, Al), and critical metals (Li, Co); Construction and Demolition Waste (CDW), from which recycled aggregates and other materials can be recovered; Urban Solid Waste (USW), including plastics, metals, and even incineration ash; industrial waste, such as electrical and non-electrical equipment, and infrastructure waste, such as pavement, end-of-life vehicles (ELV), and landfill mining waste, with the potential for the recovery of plastics and metals [29].

Urban mining presents significant pros, encompassing the conservation of natural resources through the use of secondary sources [10], the mitigation of environmental impacts associated with traditional mining, such as lower energy and water consumption, and a reduction in waste generation and pollution [9,10]. This activity also promotes the economic valorization of waste, transforming discarded materials into valuable raw materials, and drives the circular economy, reintegrating materials into the production cycle and extending the lifespan of resources [9,10]. Other advantages include the reduction of dependence on primary raw materials and the risks in their supply chain, as well as the potential for job creation in the sectors of collection, processing, and material recovery [9,29].

However, there are challenges associated with urban mining that need to be recognized: the complexity of reverse logistics due to the variety of waste with different compositions, which hinders collection, transportation, and sorting; the costs involved in reverse logistics and recovery processes are also a challenge, which may question the economic viability of the activity in the context of the circular economy, with viability dependent on the quality and volume of the material; the need for specific technologies and technical knowledge for the processing and recovery of materials can be a barrier due to their limited availability or accessibility [10,29].

In addition, the presence of hazardous substances in some waste, such as in WEEE, requires special care in handling and processing to avoid contamination and health risks [29]. The informal recycling market, operating without adequate standards, hinders the formalization and control of the value chain [10]. The lack of specific regulations and economic incentives for the formal chain discourages urban mining compared to virgin raw materials, with the taxation of WEEE being a possible disincentive [10,29]. The need for correct waste disposal by consumers is essential to feed the chain, just as the scale of production and the diversity of electronic products impact the generation and treatment of WEEE [10].

4. Processes Used in Urban Mining

This section presents the main processes (Figure 3) employed in the recovery of valuable metals from urban waste: Hydrometallurgy (processing in aqueous solutions), Pyrometallurgy (processing at high temperatures), and Biometallurgy (use of microorganisms). Various technologies, both traditional and emerging such as electrochemistry and supercritical fluids, can be applied in the scenario of Rare and Precious Metal (RPM) recovery as presented by Wang et al. [30], while Xavier et al. [29] offer a comprehensive review on key concepts and treatment methods for materials in urban waste. Additionally, Firmansyah et al. [31] reviews technological advances focused on the recycling potential of electronic waste.

Recently, Kankanamge et al. [6] investigated the factors that influence the design and adoption of technologies to make urban mining of electronic waste more sustainable, proposing a taxonomy that groups these factors into four categories: the device cluster, referring to the intrinsic characteristics of the technologies; the process cluster, which encompasses variables such as efficiency and cost; the organizational cluster, relating to the structure and policies of the entities involved; and the macro cluster, which includes external influences such as data security and intellectual property. In the following subsections, we will assess the efficiency, environmental impact, and economic viability of each process, conducting a comparative analysis of their advantages and disadvantages, aiming to identify future perspectives for metal recovery in the context of a circular economy.

4.1. Hydrometallurgy

Hydrometallurgy, which extracts metals through chemical reactions with acidic or basic solutions, typically comprises steps such as leaching, precipitation, solvent extraction, and electrodeposition. According to Tunsu et al. [32], the advantages of applying hydrometallurgical methods for the urban mining of Rare Earth Elements (REEs) include the ability to process low-quality and complex materials, obtain products of higher purity, generate less gaseous pollution compared to pyrometallurgy, reduce dependence on primary mining, and enable the recycling of materials. However, it faces significant challenges such as the complex logistics of collection and sorting, the heterogeneity of materials that require flexible processes, the need for efficient separation methods for materials with low REE content, the intensive use of chemicals with the potential generation of secondary waste, and the costs of development and industrial implementation.

4.1.1. Leaching

Leaching consists of the selective dissolution of metals from solid waste using acidic or alkaline solutions, being applied in the recovery of valuable metals from electronic waste and spent catalysts. Gomes et al. [33] reviewed the acid leaching of REEs from WEEE, pointing to urban mining as a promising strategy. Anwer et al. [34] compared different acids in the extraction of metals from printed circuit boards (PCBs), highlighting organic acids (such as citric acid) as a more sustainable alternative. Alternatively to the traditional process, Prodius et al. [35] demonstrated a hydrometallurgical route using copper salts to recover REEs and cobalt from magnetic and electronic waste, with subsequent precipitation of the REEs for reuse as oxides.

Arya et al. [36] used chemical leaching to recover copper (Cu) and lead (Pb) from WPCBs (Waste Printed Circuit Boards), warning about the need for proper management of the waste generated. Acid leaching is also fundamental in the recovery of cobalt in lithium-ion batteries, using acids such as hydrochloric and sulfuric acid, to dissolve the components, followed by techniques such as solvent extraction, ion exchange, or precipitation to separate the cobalt, as highlighted by Botelho Júnior et al. [37]. Rocchetti et al. [38] proposed multi-stage countercurrent leaching as an innovative solution to recover indium from discarded Liquid Crystal Display (LCD) screens. This approach consists of using the same acid solution to treat several stages of LCD waste, concentrating the metal in the leaching solution. Oliveira et al. [39] suggested acid leaching as the most suitable method for recovering gallium and REEs from LEDs (Light Emitting Diodes).

Martins et al. [40] explored a three-stage sulfuric leaching to recover metals from WPCBs, especially in motherboard and memory board: the first stage focuses on the recovery of iron (Fe), aluminum (Al), and tin (Sn); the second, in an oxidizing medium, selectively recovers copper (Cu), silver (Ag), nickel (Ni), and zinc (Zn); and the third, with nitric acid, solubilizes the remaining metals, with the extraction efficiency dependent on the metal/acid ratio. Agrawal et al. [41] developed an eco-friendly hydrometallurgical route to recover manganese (Mn) and nickel (Ni) from discarded tantalum capacitors, using selective leaching with hydrochloric acid that dissolves Mn (99.9%) and Ni (98.9%) while isolating tantalum (Ta), followed by solvent extraction. Finally, Tran et al. [42] reviewed leaching with thiosulfate as a benign alternative to cyanidation for recovering gold (Au) and silver (Ag) from WPCBs, addressing the specific challenges of its application in urban mining, such as reagent consumption and reaction complexity.

4.1.2. Precipitation

Precipitation separates dissolved metals by adding reagents that form poorly soluble compounds. In contrast to traditional and energy-intensive thermal treatments for dismantling PCBs, Yang et al. [43] proposed a green alternative that involves immersing PCBs in spent tin stripping solution (TSS) at room temperature, followed by the recovery of leached metals by chemical precipitation by adjusting the pH in different stages, achieving approximately 99% recovery of Sn, Pb, Fe, Cu, and Zn. This process offers advantages such as energy efficiency, waste reuse, and efficient metal recovery.

Caldas et al. [44] explored methods for selective silver recovery, proposing an effective route with two stages of sulfuric leaching, with 100% of the silver recovered, followed by silver purification by precipitation as AgCl with NaCl and the production of silver nanoparticles (AgNPs) by the Turkevich method. Lima et al. [45] used chemical precipitation as an initial step to recover aluminum from NCA (Nickel-Cobalt-Aluminum) batteries, a challenge due to the presence of aluminum in the cathode, then proceeding with the recovery of cobalt by solvent extraction and nickel/lithium by precipitation.

4.1.3. Solvent Extraction

This process involves the selective transfer of metals from an aqueous solution to an organic solvent, being applied in the recovery of precious metals and REEs from electronic waste. Tunsu et al. [46] tested different extractants (acidic, solvating and mixed extractant systems) for REEs in simulated acidic solutions and identified that the blended DEHPA–Cyanex 923 is effective in minimizing the co-extraction of iron. The use of Ionic Liquids (ILs) and Deep Eutectic Solvents (DESs) as alternatives to conventional REE recovery processes was explored by Quijada-Maldonado et al. [47] and Arrachart et al. [48], respectively. Alguacil e Robla [49] conducted a comprehensive review showing the potential of solvent extraction to recover various metals (rare earths, copper, lithium, gold, silver, palladium, platinum, etc.) from various sources using different types of extractants, discussing challenges and the future of the technique.

Zhang et al. [50] employed supercritical fluid extraction (SCFE) using supercritical carbon dioxide and a tributylphosphate–nitric acid adduct (TBP–HNO₃) to recover REEs, such as terbium (Tb), europium (Eu) and yttrium (Y), from fluorescent lamp waste, achieving extraction rates greater than 70% for yttrium and europium, and 50% for terbium. Castillo-Ramírez and Janssen [51] explored Pseudo-Protic Ionic Liquids (PPILs) for the extraction of metals relevant in urban mining. The authors tested four different PPILs for the extraction of indium, neodymium, yttrium, and lanthanum, with tri-hexylammonium octanoate showing high efficiency for all. And that indium was particularly well extracted by all PPILs tested. The authors reported the recyclability of most of the PPILs tested and the relative ease of yttrium and neodymium recovery.

4.1.4. Electrodeposition

Electrodeposition recovers metals in elemental form by applying electric current to an ionic solution, being used to obtain high-purity metals, such as copper, gold, and silver. Reyes-Valderrama et al. [52] combined acid leaching with selective electrochemical recovery, demonstrating the recovery of Cu by electrodeposition at pH 1.5 and of Zn at pH 5, although nickel did not show relevant deposition under the tested conditions. Recently, Son et al. [53] developed a gold electrodeposition process using a thiourea-based electrolyte, a less toxic alternative to cyanide, achieving 97% gold recovery with drastically reduced energy consumption (0.129 kWh/kg Au), attributed to the oxidation of thiourea at the anode. Although thiourea decomposes, electrodeposition slightly slows down this degradation compared to chemical deposition, possibly due to its regeneration at the cathode.

4.2. Pyrometallurgy

Pyrometallurgy [54,55,56,57,58] is a non-ferrous metal extraction process that uses high temperatures and consumes a lot of energy. It involves enrichment steps by smelting, conversion, and refining, being considered the most traditional and industrially used treatment. Its advantages include the ability to treat large volumes of waste, recover metals in high concentration, and process complex materials [59]. Application examples include the recovery of copper (Cu) [54], gold (Au) [60], zinc (Zn) and indium (In) [61], gallium (Ga) [62], among others. The key step is smelting (melting to separate metals by melting points), which can be performed by flash smelting processes, which use oxygenated gas for autogenous conditions, or by bath smelting, where the reaction occurs in a melt pool.

However, pyrometallurgy inevitably generates slag, soot, and toxic gases, requiring strict environmental controls, such as filters and gas treatment, to minimize pollution and ensure sustainability. The equipment is expensive, and energy consumption is high, making it unsuitable for small and medium-sized enterprises. Furthermore, it lacks selectivity for rare and precious metals and presents complexity in the recovery of pure metals [59]. The choice between hydrometallurgy and pyrometallurgy depends on the characteristics of the waste, the target metals, and environmental and economic factors, and in many cases, the combination of both may be the most efficient and sustainable solution. Therefore, future research is needed to optimize pyrometallurgical processes, reduce their impacts, and develop integrated technologies.

4.3. Biohydrometallurgy

Emerging as a promising, ecological, and economic alternative for the treatment of electronic waste, biohydrometallurgy uses microorganisms to extract and recover metals. Its main process, bioleaching, employs microorganisms such as bacteria (Acidithiobacillus ferrooxidans and Thiooxidans), fungi (Penicillium, Aspergillus, Fusarium, Alternaria, Candida), and their metabolites. Efficiency is demonstrated by works such as that of Madhavan et al. [63], who recovered copper (Cu) and gold (Au) from PCBs using Alcaligenes aquatilis; Rodrigues et al. [64] who demonstrated high efficiency of the fungus Aspergillus niger in the bioleaching of copper and gold and Thakur e Kumar [65] who used the bacterial strain Bacillus sporothermodurans ISO1 for copper and silver recovery. Other biohydrometallurgical processes include bioaccumulation (adsorption of metals in microbial cells) [66] and bioreduction (reduction of metal ions to the elemental form) [67]. The biorecovery of critical metals, such as from lamp phosphor powder, exemplifies the transition to a biologically based circular economy [68].

The advantages of biohydrometallurgy include being a sustainable process (minimizes hazardous waste and emissions, reduces energy/chemical consumption), efficient (selective recovery even at low concentrations), and flexible (adaptable and integrable with other technologies) [54]. Despite this, it has limitations such as low reaction rates, the possibility of metal precipitation, long process times, and potential toxicity of metals to microorganisms. Factors such as microorganism choice, surface area, pulp density, precursor, temperature, and pH are essential for success [54]. Although it still faces optimization and industrial scalability challenges, continuous development indicates a promising future for its application in waste recovery, contributing to sustainability and the circular economy.

4.4. Comparative Analysis Between the Processes

The economic viability of recovering metals from WEEE is multifaceted. Figure 4 presents an overview of the main aspects of each method, focusing on efficiency, scalability, economic viability, and environmental impact.

The purity of the recovered metals is generally high in formal processes (hydro and pyro), with pyrometallurgy being capable of achieving very high purity on a large scale, and hydrometallurgy proving effective for high purities in specific cases. Transportation costs and the absence of specific tax incentives in Brazil are significant economic barriers that negatively affect the viability of all formal methods. Furthermore, each method has its own cost/benefit factors: pyrometallurgy requires high capital investment and consumes a lot of energy, being mainly viable on an integrated large scale; hydrometallurgy has lower energy costs and is suitable for a smaller scale, but faces costs with chemical reagents and effluent disposal; biohydrometallurgy is promising due to its low cost and minimal use of chemicals, but still lacks economic feasibility studies on an industrial scale.

5. Perspectives of Urban Mining: A Comparison Between Brazil and the European Union Context

Since the main objective of urban mining is to extract precious metals, base metals, plastics, glass, and other reusable components, transforming what was previously considered waste into economic resources for some productive chain, the inputs produced compete with the extraction of virgin natural resources, and may, in principle, reduce the environmental impacts associated with conventional mining.

Many studies address the opportunities offered for the recycling of composite materials from different waste streams [69] and few contemplate the barriers and challenges faced by urban mining [1,2]. Its development faces challenges as complex as those of conventional mining, although of different natures.

While traditional mining deals with resource depletion, large-scale environmental impacts, and social conflicts related to land ownership [70], urban mining stumbles upon issues such as the complexity of waste composition, the presence of hazardous substances, the lack of adequate collection and processing infrastructure, the informality of the sector, the need for efficient and economically viable separation technologies, and the implementation of public policies that encourage recycling and extended producer responsibility.

Table 2. Characteristics of Conventional and Urban Mining.

Characteristic	Conventional Mining	Urban Mining
Source of Resources	Mineral deposits (ores) located in the Earth’s crust, generally in remote and specific areas.	Waste and discarded products in urban areas, including electronic waste, construction and demolition waste, end-of-life vehicles, and urban solid waste.
Environmental Impact	Destruction of ecosystems, deforestation, soil and water pollution, waste generation (tailings and sterile material), landscape alteration.	Reduced pressure on natural resources, decreased pollution, lower energy consumption, reduced volume of waste sent to landfills, recovery of degraded areas.
Location	Generally in rural or remote areas, often in regions of great biodiversity or environmental importance.	Predominantly in urban and peri-urban areas, close to consumption and waste generation centers.
Complexity	Complex extraction, beneficiation, and refining processes, which require large investments in infrastructure and technology.	Complex processes of collection, sorting, dismantling, separation, and refining, which require cutting-edge technologies and efficient logistics. The heterogeneous composition of waste is a major challenge.
Regulation	Rigorous environmental legislation, complex environmental licensing, requirements for the recovery of degraded areas, need for constant monitoring.	Legislation under development, need for specific regulation for the sector, definition of responsibilities, incentives for recycling and reverse logistics, combating informality.
Economy	Traditional sector, with a large impact on the global economy, job creation, and foreign exchange earnings, but also with negative externalities (environmental and social costs).	Growing sector, with the potential to generate green jobs, reduce dependence on imports, boost technological innovation, and promote the circular economy.
Challenges	Resource depletion, social conflicts, environmental impacts, increasing extraction costs, rigorous environmental regulations.	Efficient selective collection, separation technologies, reverse logistics, traceability of materials, economies of scale, public awareness, specific regulations, combating informality.
Perspectives	Development of more sustainable mining technologies, recovery of degraded areas, corporate social responsibility.	Expansion of selective collection, development of advanced recycling technologies, promotion of the circular economy, creation of markets for recycled materials, public awareness.

presents a comparison between conventional and urban mining.

In the global scenario, Brazil and Europe contrast in their approaches to mining, both conventional and urban. Brazil, possessing vast mineral reserves and marked by social inequalities that have historically sustained the workforce in conventional mining, faces the challenge of reconciling economic development with the effective application of its environmental legislation, often permeated by gaps and enforcement challenges [70]. The European Union (EU), on the other hand, driven by resource scarcity and growing environmental awareness, as evidenced by its policies on critical raw materials, directs its efforts toward urban mining as a central strategy to ensure access to essential materials, reduce dependence on imports, and promote a circular economy [11,71,72]. This is reflected in its comprehensive legislative framework for WEEE, such as the WEEE and RoHS Directives [11]. In addition, the mastery of specific technologies applicable in urban mining within developed European nations allows for the establishment of virtuous partnerships to the capital and geopolitics of selling technologies or services and acquiring products thus mined at a low price and without pollution in European countries.

In view of this, while Brazil seeks to optimize the management of its natural resources and mitigate the socio-environmental impacts of traditional mining, many European countries, particularly within the EU, invest in advanced recycling technologies and in the creation of value chains for recovered materials. This aims to strengthen their strategic autonomy and reduce their ecological footprint [1,5], although Baldé et al. [11] note that even EU Member States face challenges in meeting legally binding collection targets for e-waste.

The fundamental distinctions in urban mining approach and infrastructure between Brazil and the European context, particularly the European Union, are multifaceted and reflect their different socioeconomic, environmental and regulatory landscapes.

Table 3. Structural and approach differences in urban mining—Brazil vs. Europe/European Union.

Characteristic	Brazil	Europe/European Union
Main Drivers and Primary Focus	Reduction of waste volume in landfills; social inclusion of the informal workforce.	Resource scarcity; circular economy goals; security of critical metals supply.
Legislative Framework	National Solid Waste Policy (PNRS) and decrees: legal framework under development, with gaps in implementation, enforcement, and clarity of responsibilities.	More advanced and harmonized legislative framework (WEEE, RoHS Directives, Circular Economy Package), focusing on Extended Producer Responsibility; Variation in effectiveness among member states.
Infrastructure	Lack of adequate selective collection and processing infrastructure; logistics challenges (continental dimensions).	More developed and formalized collection and recycling infrastructure, despite challenges in meeting collection targets.
Technology and Innovation	Significant technological barriers; initial processing primarily local, export of noble-metal-rich components; growing research and development phase.	Investment in advanced recycling technologies and value chain creation; technological mastery and pursuit of strategic autonomy.
Informal Sector Integration	Prominent presence of informal collectors; need for inclusive approaches and formalization.	Predominantly formalized sector; challenges in uniform policy implementation.
Public Awareness	Low public awareness regarding correct WEEE disposal.	Growing consumer awareness and pressure for responsible practices.
Economic and Fiscal Incentives	Logistics costs and lack of specific fiscal incentives as barriers.	Pursuit of strengthening economic autonomy and reducing ecological footprint; creation of markets for recycled materials.

summarizes the main structural and focus differences that shape urban mining development in each region.

In contrast to the challenges observed in Brazil, European countries, guided by the WEEE Directive and national regulations, have developed relatively consolidated WEEE management systems, characterized by established collection schemes and formal recycling infrastructure [73]. Extended Producer Responsibility (EPR) plays a central role, assigning responsibility for end-of-life management to producers, who often operate or finance collective take-back schemes. These systems aim to maximize collection rates and channel WEEE towards appropriate treatment facilities to recover valuable materials and minimize environmental impacts [73,74].

Beyond basic recycling, there is a growing emphasis on higher tiers of the waste hierarchy, such as preparation for re-use. Experiences from several EU member states, including the UK, Belgium, France, Austria, and Spain, demonstrate that successful preparation for re-use is enabled by factors such as clear targets, adequate funding mechanisms, collaboration among stakeholders (including social enterprises), and infrastructure that facilitates collection and assessment of WEEE suitability for re-use [75]. Furthermore, analyses focusing on specific product streams, like small WEEE in Germany, highlight how manufacturer take-back systems and the implementation of tailored end-of-life strategies such as component reuse and remanufacturing can significantly improve resource recovery and potentially offer economic and environmental benefits compared to conventional recycling [76].

Despite these advancements and consolidated systems, challenges persist in Europe, including issues related to unreported WEEE flows through scavenging, mixing with other waste streams, and illegal exports [74]. Nevertheless, the European experience, particularly in developing formal collection networks, implementing EPR effectively, and promoting higher-value recovery strategies like re-use and remanufacturing, offers valuable insights and potential models for countries like Brazil seeking to enhance their urban mining capabilities within a framework of circular economy.

Therefore, the transposition of models observed in European countries, especially those from the European Union with advanced legislative frameworks, to Brazil requires a critical analysis, considering the distinct socioeconomic, environmental, technological, and regulatory specificities of the country. The rationale for focusing comparative legislative analysis on the EU lies in its harmonized and advanced directives on WEEE and circular economy, which serve as a significant international benchmark, despite variations in national implementation [11].

The direct application of European models to the Brazilian context ignores the profound existing differences. Brazil, although a country rich in mineral resources, faces complex challenges to ensure that conventional mining is conducted sustainably. Institutional fragility, precarious enforcement, and the prevalence of negligent practices have resulted in serious environmental and social disasters, such as the collapse of the Barragem do Fundão em Mariana (Minas Gerais) [77], a tragic landmark that exposed the flaws in the licensing system and the lack of socio-environmental responsibility of mining companies in this country.

The Mariana disaster, a tragic landmark of Brazilian conventional mining, serves as a stark warning: negligence and precarious enforcement cannot be repeated in the implementation of urban mining. Although promising, this modality, if conducted improperly, can replicate negative environmental and social impacts [78,79], such as soil and water contamination by heavy metals present in electronic waste, the exposure of workers to toxic substances during sorting and processing, and the creation of environmental liabilities resulting from the inadequate disposal of non-recoverable waste.

To avoid repeating the mistakes of conventional mining, urban mining must be guided by rigorous control and prevention measures. This includes conducting detailed and comprehensive environmental impact studies, adopting clean and innovative technologies for the separation and processing of materials, and guaranteeing the active participation of civil society in the planning and oversight of activities. Furthermore, it is essential that mining companies assume extended responsibility [80,81,82] for the management of waste generated at all stages of the process, from selective collection to environmentally sound final disposal, prioritizing the traceability of materials and the implementation of circular economy practices.

Even so, the urgency of urban mining manifests itself differently in the Brazilian context compared to the European one, although they may share common sustainability goals. Within Europe, and particularly in the European Union, the perception of natural resource scarcity, the existence of strong environmental regulations (such as the EU WEEE Directive), and the ambition to lead the transition to a circular economy drive a pressing need to implement urban mining on a large scale [11]. Dependence on imports of critical raw materials, coupled with growing consumer awareness and pressure for responsible business practices, makes urban mining a strategic priority to ensure the competitiveness of European industry and security of supply.

From a geopolitical and economic point of view, security of supply for items that Europe does not produce can be achieved through diversified partnerships in Asia, Africa, and Latin America with contributions of technology and capital sufficient to transform their strategic needs into commodities. This strategy has been used by several economic and technological powers throughout recent history, marking a kind of neocolonialism.

Furthermore, while Europe stands out for its selective collection and recycling infrastructure, Brazil still faces significant challenges in the management of urban solid waste. Informality in collection, lack of adequate infrastructure, and low public awareness hinder the separation and routing of waste to urban mining. Also, some situations related to conventional mining demonstrate that Brazilian environmental legislation, although advanced in some aspects, lacks effective mechanisms to guarantee the accountability of companies and the reparation of damages caused by their activities [70,83,84]. Therefore, urban mining in Brazil cannot be presented as an environmental merit in itself without a set of guarantees of its efficacy, efficiency, and effectiveness.

Another point that deserves highlighting is the social issue. The experience of the city of Trento, in Italy, illustrates the implementation of a program coordinated by local recycling companies. Collaboration with entities specialized in waste management suggests a more formalized approach through selective collection [82,85,86]. In Brazil, informality and the presence of recyclable material collectors in situations of social vulnerability require a differentiated approach, which promotes social inclusion and income generation for this population.

In Brazil, the urgency of urban mining is revealed in a less immediate, but equally relevant way. Although the country has abundant mineral resources, conventional mining is only considered an effective social function at the beginning of the undertaking, after which it responds to the demands of the national and international market by lowering its costs, increasing its production without assuming all the environmental and social externalities it generates in the process and in the increase in the scale of production [70,83,84]. Therefore, unbridled conventional mining brings significant environmental impacts and social and environmental costs. Urban mining emerges as an alternative to diversify sources of raw materials, reduce pressure on fragile ecosystems, and promote social inclusion through the generation of green jobs and the formalization of the sector [87,88,89].

In addition, the increasing production of electronic waste and other complex waste streams requires urgent solutions to prevent soil and water contamination, protect public health, and recover valuable materials that can be reintroduced into the production chain. Thus, while Europe sees urban mining as a matter of economic security and environmental leadership, Brazil needs to adopt it as a strategy to promote sustainable development, reduce social inequalities, and protect its vast natural heritage.

The news from the National Electric Energy Agency [90] about the expressive growth of 8.84 GW in micro- and mini-distributed generation of electricity, in 2024, highlights a critical point for the sustainability of the Brazilian energy sector: the urgent need to prepare the country for the management of the life cycle of the equipment used in these facilities. As in the case of large solar plants, the expansion of micro and mini-distributed generation, driven by photovoltaic solar panels installed in homes, businesses, and rural properties, will inevitably lead to a significant increase in the volume of electronic waste (e-waste) containing valuable and potentially hazardous materials [91].

In this scenario, urban mining becomes a key piece to ensure the environmental and economic sustainability of micro and mini-distributed generation. By recovering materials such as silicon, silver, copper, and aluminum present in end-of-life solar panels, urban mining can reduce the demand for virgin raw materials, reduce the environmental impacts of ore extraction and processing, and create new business opportunities and green jobs. However, the implementation of urban mining on a large scale in the context of micro and mini-distributed generation presents specific challenges. The geographical dispersion of facilities, the lack of adequate collection and sorting infrastructure, and the absence of specific regulations for the management of solar panel waste hinder reverse logistics and efficient material recovery.

To overcome these challenges, it is essential that the Brazilian government, in partnership with the private sector and civil society, develops public policies that encourage selective collection, the creation of specialized recycling centers, the promotion of extended producer responsibility, and the awareness of consumers about the importance of the correct disposal of end-of-life solar panels. In addition, it is necessary to invest in research and development of innovative recycling technologies, which allow the efficient recovery of materials present in solar panels, minimizing the costs and environmental impacts of the process.

By embracing urban mining as an integral part of the strategy to expand micro and mini-distributed generation, Brazil will be able to ensure that the energy sector becomes not only cleaner and more decentralized, but also more circular and sustainable. Thus, the role of the government is, first and foremost, to regulate the market so that it is virtuous by imposing on the private sector and, indirectly, on photovoltaic generators, the environmental costs of this technology. In this way, whoever profits and whoever benefits must internalize the environmental costs of the activity within a long-term vision that goes from production to decommissioning.

6. Knowledge Production and Technological Appropriation on Urban Mining in Brazil

The mapping of Brazilian scientific production on urban mining reveals a field of investigation that, although it demonstrates a recent growing interest, is still in a phase of development compared to other environmental areas or international production, especially European. A search carried out in March/2025 on the Web of Science resulted in 633 documents found for the term “urban mining” (all fields), of which 573 are articles, with 75 being reviews. Brazil ranks 6th among the countries that have produced the most articles on the topic, Figure 5.

The existing literature, dispersed in journals of various areas (engineering, chemistry, environmental sciences, management), conference proceedings, and, expressively, in theses and dissertations, tends to concentrate on specific thematic niches. Studies dedicated to the quantitative and qualitative characterization of flows such as Waste Electrical and Electronic Equipment (WEEE), in which it seeks to identify precious and critical metals, and Construction and Demolition Waste (CDW), whose focus lies on the potential for reuse of aggregates, predominate.

Investigations on technological routes for the processing of these wastes were also recovered, ranging from physical pre-treatments to metallurgical processes on a laboratory or pilot scale, often adapting technologies or seeking lower-cost alternatives. An analysis of this corpus suggests a preference for applied technical approaches, whose central objective seems to be the establishment of the technical–economic feasibility of material recovery, precluding discussions about the social, political contexts and the broader implications of urban mining in Brazil to a secondary plane.

Considering the growing challenge of managing WEEE in Brazil, whose generation exceeds population growth and which stand out for their complexity, potential hazard, and for containing valuable materials, the National Solid Waste Policy instituted Reverse Logistics Systems (RLS) as fundamental instruments for the transition to the circular economy [10,22]. In this context, urban mining emerges as a strategy fostered by RLS, although the effectiveness of both approaches faces significant paradoxes. High costs, logistical challenges, the informality of the recycling chain, public ignorance, the lack of adequate infrastructure and specific tax policies are bottlenecks that question the real contribution of these approaches to sustainability and emissions reduction, demanding the recognition of these obstacles to drive technological and regulatory solutions [10]. The lack of formal RLS, especially in metropolitan regions, contributes to a recycling rate estimated at only 2%, also influenced by the lack of reliable data, the significant role of the informal sector, and the continental dimensions of the country [92].

Aiming to improve urban mining, studies have focused on the detailed characterization of waste and the development of processing routes. Castro e Pereira-Filho [93], for example, carried out an exploratory study of the chemical composition of Printed Circuit Boards (PCBs) from hard drives, where it was possible to identify about twenty chemical elements through Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Flame Atomic Absorption Spectrometry (FAAS). Using exploratory data analyses such as Principal Component Analysis (PCA) and correlation maps, it was also possible to make significant associations, demonstrating that the direct analysis of fragments combined with chemometrics is promising for the characterization and planning of recycling routes.

In a complementary way, Castro et al. [94] proposed the combined use of Laser-Induced Breakdown Spectroscopy (LIBS) and Parallel Factor Analysis (PARAFAC) to characterize PCBs, improving the identification of interferents and the accuracy in the classification of elements such as Au and Ag. The characterization of other WEEE, such as Light-Emitting Diodes (LEDs) and lithium-ion batteries, reveals not only the presence of valuable and critical materials (Cu, Ga, Y, In, Au, Ag in LEDs and Co, Ni, Li in lithium-ion batteries), but also toxic elements (such as Pb and As in LEDs) and a compositional heterogeneity that challenges recycling processes [95,96].

Overcoming technological barriers is identified as a critical factor in Brazil, which, despite being the largest generator of e-waste in South America, only performs the initial processing stage locally [97]. Using the DEMATEL (Decision Making Trial and Evaluation Laboratory) method based on expert opinion, the authors pointed out technology as the only primary and causal barrier, directly influencing others such as technical knowledge, pollution control, costs, and consumer. This lack of advanced technologies and specialized knowledge, added to the low collection flow (~2%), makes it impossible to install sophisticated recovery plants in the country, resulting in the export of components rich in noble materials [97]. In view of this, several processing approaches have been investigated. Hydrometallurgy is frequently cited as a promising route [29,45,55], with studies focusing on the optimization of parameters such as acid leaching (e.g., H₂SO₄, HNO₃, aqua regia), solid/liquid ratio, pH, and redox potential to recover metals such as Cu, Ag, Fe, Au, Ga and Rare Earth Elements (REE) from PCBs, LEDs, and other sources. Separation techniques such as selective precipitation, solvent extraction, ion exchange, and membrane separation (nanofiltration, reverse osmosis) are explored for the purification and concentration of metals and recovery of reactants [45,98].

Alternatives and emerging technologies are also highlighted in the search for sustainability. Bioleaching using fungi such as Aspergillus niger has proven efficient in the recovery of Cu and Au from PCBs, also enabling the synthesis of metallic nanoparticles [64]. Bio-hydrometallurgy in general is pointed out as a promising innovation, especially for critical raw materials [29,37,68]. Biphasic Aqueous Systems (BAS) emerge as a “green” alternative for the recovery of bismuth and gold, minimizing the use of organic solvents and operating under mild conditions [99,100]. Magnetic Nanohydrometallurgy (MNHM) is presented as an innovative nanotechnological approach for the selective separation of lanthanides [101].

Other techniques such as gravity concentration [102], hybrid (mechanical-thermal) approaches for photovoltaic panels [103] and supercritical water (SCW) technology for simultaneous recycling of solar panels and effluent treatment [104] are also investigated. The recovery of REE, given their technological importance and supply risk, is a particular focus, although acid leaching still predominates and recovery from PCBs remains a challenge [33,105]. Similarly, the recovery of indium from LCDs faces analytical and market challenges in Brazil [106].

As already mentioned, urban mining is not restricted to WEEE, also covering CDW, where the concept of buildings as material banks proposes to treat buildings as recoverable sources [107]. Although Brazil has research in the area, it contrasts with European countries due to the lack of robust public policies, with systematized data and incentive policies being necessary to overcome the competitiveness of virgin materials. The incorporation of waste such as milled asphalt pavement [108] and polyethylene [109] in asphalt mixtures also demonstrates potential, although the environmental benefits depend on the technologies and energy matrices employed and more Life Cycle Assessment (LCA) studies are needed. The recovery of lead from motorcycle batteries also presents economic and environmental relevance, with significant forecasts of obtaining it via urban mining, but faces capacity and illegal recycling challenges [110].

The spatial and social perspective of urban mining reveals additional complexities. A study in the Metropolitan Region of Rio de Janeiro (MRRJ) identified significant potential, but also a concentration of recyclers that leaves areas of high generation isolated, reinforcing the need to optimize routes and improve data management and collection [81]. Universities emerge as promising sources of WEEE (“urban mines”), however, even in higher education communities, there is ignorance about proper disposal and reverse logistics, with the lack of infrastructure and information being significant barriers [111]. Urban mining is strongly connected to Sustainable Development Goals (SDGs) such as industry/innovation (SDG 9) and responsible consumption/production (SDG 12), but presents social trade-offs, especially linked to informality and precarious working conditions of waste pickers, demanding ethical and inclusive approaches [28].

The geography of urban mining is uneven, shaped by the local political economy, resulting in disparities in practices and technologies between different urban contexts. For example, while the London Larger Urban Zone (LLUZ) and Sao Paulo Macrometropolis (SPMM) stand out for the predominance of formal companies and advanced recycling technologies, the Greater Accra Region (GAR) faces significant challenges with informal collection and rudimentary techniques that generate environmental and health impacts [82]. In addition, the mining activity itself, even urban, can entail socio-environmental risks, such as subsidence in Maceió, requiring tools such as Geographic Information System (GIS) and Multi-Criteria Decision Aid (MCDA) for mapping vulnerabilities and supporting urban planning [112]. The lack of standardization in sustainability reports on waste management also hinders a complete view of flows and the advancement of the circular economy [113].

In summary, urban mining, aligned with the principles of the circular economy, is presented as an important strategy in the face of pressure on primary resources and the increase in waste generation in Brazil. Although it represents an opportunity to recover valuable and critical materials from various anthropogenic sources, such as WEEE and CDW, its consolidation depends on overcoming technological, logistical, economic, informational, and socio-political barriers. The development and implementation of characterization and processing technologies, combined with effective public policies, functional reverse logistics systems, greater public awareness, and socially inclusive approaches, are fundamental for urban mining to reach its potential to contribute to sustainability and the efficient management of resources in the country.

7. Legal Dimension of Urban Mining: Effectiveness of Brazilian Legislation and Obstacles to Overcome

Regarding the legal dimension, urban mining, particularly with regard to the utilization of WEEE, is intrinsically linked to the normative framework that regulates the management of solid waste in the country. The evolution of this legislation, from the establishment of the National Solid Waste Policy (NSWP) [22], in 2010 to the most recent decrees [23,24,25,26] that improve the regulation of WEEE management, demonstrates a normative progress towards shared responsibility and reverse logistics. However, the mere existence of a set of laws and regulations does not guarantee its effectiveness.

This section proposes to deepen the critical analysis of Brazilian legislation applicable to urban mining, examining to what extent the current legal framework is effective in driving this activity, as well as the main persistent challenges in its practical implementation and enforcement. From an assessment of the normative scenario and the obstacles encountered in its application, it will be possible to identify the gaps and the needs for legislative improvement for the full development of urban mining as a strategy for sustainability and the utilization of secondary resources in Brazil.

The trajectory of waste management in the European Union [17,18,19,20,21], with its progressive legislative sophistication guided by the search for sustainable practices and the principles of the circular economy, serves as an important benchmark for the analysis of policies in other regions. Although Brazil has its particularities and challenges inherent to international experiences, such as the European one, often influence the adoption of models and the normative evolution in developing countries. In this context, the understanding of international approaches and the principles that govern the management of WEEE helps to examine the effectiveness of Brazilian legislation applicable to urban mining.

The evolution of waste management in the European Union (Table 2) demonstrates a progressive legislative sophistication, guided by the search for sustainable practices. The

Table 4. Waste legislation in Europe.

Year	Approach
1970	Europe: Directive 75/442/CEE—prioritization of waste elimination
1990	Directive 91/156/CEE—introduction of the paradigm of integrated management and prevention at the source
2006–2008	Directive 94/62/CE—specific directives for packaging Consolidation and improvement of the legal framework (Directive 2006/12/CE and Waste Framework Directive 2008/98/CE)
2008	Incorporation of the principles of the circular economy

shows that, in the 1970s, Europe adopted Directive 75/442/CEE [17], which prioritized the elimination of waste, with the aim of mitigating the environmental impacts associated with final disposal. Although this approach was fundamental, it focused on solving the problem in a reactive way, that is, after the generation of waste.

Directive 91/156/CEE [18], in the 1990s, introduced the paradigm of integrated management, shifting the focus to prevention at the source and the valorization of waste. This change represented a significant conceptual advance, promoting the hierarchization of management strategies. Concomitantly, specific directives for waste streams, such as 94/62/CE for packaging, were promulgated, complementing the framework legislation and establishing specific requirements for each type of waste.

The period between 2006 and 2008 was characterized by the consolidation and improvement of the legal framework. Directive 2006/12/CE [19] codified the pre-existing legislation, while the Waste Framework Directive (2008/98/CE) [20] consolidated the management hierarchy, with emphasis on prevention, reuse, recycling, and valorization, and strengthened producer responsibility.

From 2008 onwards, the legislation incorporated the principles of the circular economy. The 2018 Circular Economy Package, for example, established ambitious targets for recycling and reducing final disposal, aiming for a transition to a more sustainable production and consumption model. This trajectory demonstrates the EU’s commitment to sustainability in waste management, continuously seeking to optimize policies and internalize the principles of circularity.

The European directives on WEEE are well formulated, with a focus on Extended Producer Responsibility, which seeks to involve manufacturers in the product life cycle. The EU WEEE Directive, for example, sets criteria for collection, treatment, and recovery [11]. However, its effectiveness across Member States varies; efficient enforcement, public awareness, and adequate infrastructure for collection and recycling are crucial. Baldé et al. [11] report that while Europe (as a region) documents a formal collection and recycling rate of 42.8% for e-waste, many EU Member States struggle to meet their specific, legally binding collection targets, with only a few achieving them by 2022. For WEEE policies to be successful, it is necessary to invest in these areas and ensure coordination between legislation, companies, consumers, and government agencies.

Although Brazil is independent, some practices of European companies (and those of other countries) influence the use of some models already adopted by other countries. The search for sustainable practices in waste management has driven legislative evolution in various regions of the world, Brazil has demonstrated a progressive development of its normative structure for the governance of WEEE, consolidating a comprehensive legal framework that encompasses laws, decrees, normative instructions, and technical standards. This normative set aims not only to minimize the negative impacts of improper disposal but also to promote the transition to a circular economy model, promoting the use of resources present in WEEE.

The National Solid Waste Policy (Law nº 12.305/2010) [22] bases the management of Waste Electrical and Electronic Equipment (WEEE) on shared responsibility and reverse logistics. Distributing responsibilities among manufacturers, importers, distributors, merchants, consumers, and the government, the NSWP integrates management, aiming at proper disposal. The policy aims to assign manufacturers the responsibility for the environmental costs of the production, use, and disposal of WEEE (such as pollution and resource depletion), encouraging these costs to be reflected in the final price of the products. This encourages the prevention of waste generation, through the development of more durable and less polluting products.

In addition, the NSWP prioritizes the reuse of equipment, the recycling of its components, and the recovery of valuable materials, thus minimizing the amount of waste that reaches landfills and the associated environmental impact. Co-responsibility encourages sustainable practices, from product design to its disposal, closing the life cycle and promoting the circular economy. The aforementioned Policy thus seeks to mitigate waste generation, conserve natural resources, and reduce pollution, contributing to sustainable development. Reverse logistics operationalizes the manufacturer’s responsibility, ensuring the collection and proper processing of WEEE, while consumer participation is fundamental for the success of the system.

Complementing the NSWP, recent decrees have improved the regulation of WEEE management, with emphasis on Decree nº 10.240/2020 [23], which establishes goals and deadlines for the implementation of reverse logistics; Decree nº 10.657/2021 [24], which, by promoting the Pro-minerals Policy and defining criteria for strategic minerals, indirectly drives urban mining of WEEE; and Decrees nº 10.936/2022 [25] and nº 11.413/2023 [26], which promote improvements in the regulation of the PNRS and institute the Reverse Logistics Recycling Credit Certificate, the Structuring and Recycling Certificate of General Packaging, and the Future Mass Credit Certificate, within the scope of reverse logistics systems, respectively. The convergence of these legal instruments strengthens the regulatory structure and creates an environment conducive to the development of urban mining, a practice that aims at the recovery of metals and other valuable materials from WEEE, aligning with the principles of the circular economy.

The standardization of processes and the guarantee of safety and efficiency in the management of WEEE are ensured by technical standards of the Brazilian Association of Technical Standards. Brazilian Standard—NBR 10.004:2004 [13] establishes the classification of solid waste according to its risks, providing guidelines for the proper handling of WEEE. Standards NBR 16.156:2013 [14] and NBR 15.833:2018 [15] specify the requirements for the reverse manufacturing of electro-electronics and refrigeration appliances, respectively, promoting recycling and material recovery. Additionally, NBR IEC 63.000:2019 [16], harmonized with the European RoHS (Restriction of Hazardous Substances) Directive, regulates the restriction of hazardous substances in electrical and electronic equipment, contributing to the protection of human health and the environment.

Although the normative advance is remarkable, the full implementation of WEEE management in Brazil still faces significant challenges. The complexity of the production chain, the high informality in the recycling sector, the insufficient awareness of the population about the correct disposal, and the need for greater investments in collection and processing infrastructure represent obstacles to be overcome.

To achieve the sustainability objectives outlined in the NSWP, the intensification of enforcement of compliance with the legislation, the stimulation of technological innovation in recycling processes, the strengthening of articulation between the different levels of government (municipal, state, and federal), and the promotion of environmental education campaigns become essential. Future research should prioritize the evaluation of the impact of current legislation, the identification of bottlenecks in the implementation, and the proposition of solutions for the improvement of the system, aiming at a more efficient and fully aligned WEEE management with the principles of the circular economy.

In Brazil, many practices are still in initial stages or are adopted incompletely. This difference can be explained by the variation in environmental regulations and the level of social and economic pressure that motivates companies to adopt more sustainable practices. In developed countries, stricter environmental legislation and the growing consumer demand for sustainable practices contribute to greater adherence to these initiatives.

Critical Discourse Analysis

Critical Discourse Analysis (CDA) is a valuable theoretical-methodological approach for critical organizational studies, as it contributes to the reflection on contemporary social issues and seeks to denaturalize beliefs that sustain structures of domination. Although the use of CDA in Administration is not recent, its application is still limited, and the analysis of the textual dimension is not always explored in depth. Our article relies on the theoretical and methodological assumptions of CDA, as proposed by Norman Fairclough (2010) [27], and we offer subsidies for the analysis of the representational dimension, illustrating its operationalization. Our objective is to clarify aspects related to the linguistic analysis of normative texts between Brazil and Europe.

The analysis of the National Solid Waste Policy (NSWP) from the perspective of Critical Discourse Analysis (CDA) reveals a discrepancy between its normative discourse and practical application. Textually, the technical language present in Law nº. 12.305/2010 [22], such as in Article 9 when defining the waste management hierarchy, hinders comprehension by the lay public and limits citizen participation in social control and guideline implementation. Furthermore, the legislation presents ambiguities in the definition of responsibilities. Article 18 attributes waste management to municipalities, while Articles 16 and 17 stipulate that states complement the guidelines, leading to an overlap of competencies and hindering the efficient execution of actions.

Another critical aspect is the emphasis on sanctions rather than incentives. Article 3 of Decree nº. 12.189, enacted in 2024, prescribes penalties for non-compliance with regulations, which may generate resistance among the involved stakeholders. To foster voluntary adherence to sustainable practices, it is imperative to combine punitive mechanisms with incentive and engagement strategies.

Discursively, the adoption of the formal and impersonal language characteristic of legal norms can distance official discourse from the needs of the population. The legal language of the NSWP, specifically in Article 3, paragraph XVII, defines “shared responsibility for the life cycle of products”, but without clarifying practical means of implementation. This lack of clarity impedes effective application of the norm. The interconnection between laws also complicates understanding of the policy. Article 51 of Law nº. 12.305/2010 [22] refers to Law nº. 9.605/1998 [114], which addresses environmental sanctions, thereby requiring knowledge of various norms for a comprehensive interpretation.

Waste generators are depicted solely as passive agents, subject to legal obligations without incentives for active participation. Article 33 of Law nº. 12.305/2010 [22] imposes upon manufacturers, distributors, and retailers the creation of reverse logistics systems, yet lacks clear guidelines for engagement and awareness, thereby limiting their effectiveness in promoting sustainable practices.

Socio-historically, the NSWP reflects the ideology of ecological modernization, which seeks to balance economic development and sustainability. Article 7, item II, stipulates that waste management should “stimulate sustainable development through the use of environmentally sound technologies”. This modernization is further underscored by Article 44, which provides for incentives for sustainable practices, thus combining regulation with economic stimuli.

However, this ideology can justify greenwashing practices, masking unsustainable production and consumption models. Article 33 of Law nº. 12.305/2010 [22] mandates reverse logistics systems, but without efficient oversight, this allows for merely formal compliance. Power dynamics in the formulation and implementation of public policies frequently result in the marginalization of vulnerable groups. Although Decree nº. 10.936/2022 [24] recognizes the participation of recyclable and reusable waste pickers, legitimizing their inclusion in the production chain through Article 36, the normative text does not specifically detail their rights and duties. This lack of detailed specification can limit their effective integration and protection within the formal waste management system.

Despite its robust structure, the legislation often fails in practice, rendering shared responsibility fragile and leading to problems in waste disposal. Consequently, the lack of planning adapted to the reality of each municipality exacerbates environmental challenges. Article 54 of Law nº. 12.305/2010 [22] mandates the elimination of open dumps and the implementation of sanitary landfills, but without considering local specificities, which hinders its application. For cities with fewer than 50,000 inhabitants, the deadline for compliance was set for 2 August 2024, however, many municipalities have yet to meet this requirement, highlighting implementation difficulties and the need for solutions more tailored to regional conditions.

The effective adoption of circular business models, the strategic use of technology, and the strengthening of Extended Producer Responsibility are fundamental elements for a more efficient and equitable waste management system. In this context, CDA is an essential tool for highlighting hegemonic discourses and revealing the power relations underlying environmental policies, thereby contributing to the improvement of regulatory frameworks and the inclusion of historically marginalized actors.

8. Conclusions

Urban mining in Brazil is distinct from models in other regions, like the EU, primarily focusing on waste reduction and integrating the informal workforce rather than critical metal scarcity. Significant gaps exist in Brazil regarding knowledge production and technological appropriation for critical metal recovery from WEEE, which requires sophisticated technologies and greater incentives for research and development. The Brazilian legal framework, despite evolving, faces challenges in practical implementation due to a lack of clarity, ambiguities, and enforcement difficulties. The informal recycling sector and low public awareness further contrast with the more consolidated infrastructure in many European countries.

To advance this sector, policy recommendations include implementing fiscal incentives such as tax exemptions and credits for companies investing in advanced recycling technologies and formalizing informal workers. Crucially, technical and professional training programs are needed to empower workers for efficient and safer recycling technologies, fostering better working conditions and integration into industrial processes. Establishing quality standards for recovered metals is also vital to encourage their reinsertion into the productive chain.

Future research should prioritize developing efficient and sustainable recycling technologies adapted to Brazil’s heterogeneous waste. Detailed analyses of the social and environmental impacts of urban mining in various national contexts are necessary, alongside evaluating the economic viability of different business models. Further investigations should focus on technological solutions tailored to the Brazilian reality, identifying bottlenecks in reverse logistics, and exploring social inclusion models that ensure fair working conditions. Assessing the real impact of current legislation and identifying obstacles to its practical application are also critical research areas.

9. On the Use of Artificial Intelligence

In accordance with the guidelines for the ethical and responsible use of Generative Artificial Intelligence (AI), the production of this article was aided by AI tools at various stages of the research, writing and image production process. It is essential to emphasize that all outputs generated by AI tools were subjected to rigorous curation and validation by the authors, ensuring the scientific accuracy and integrity of the final content.