697 Parallel to this trend, the accelerated consumption of electronic devices, particularly mobile phones, has led to a rapid increase in Waste Electrical and Electronic Equipment (WEEE), which represents both a growing environmental burden and a strategic secondary resource. By 2025, it is estimated that more than 18 billion mobile phones will be in use globally, while only 22.3% of global e-waste is formally collected and recycled [7], [8]. These devices contain high concentrations of valuable metals, often exceeding those found in primary ores, yet insufficient recycling infrastructure has resulted in the accumulation of end-oflife mobile phones and the loss of critical materials [9], [10]. Urban mining, through Recovery and Reuse (R&R) processes, has therefore emerged as a complementary strategy to conventional mining, enabling the valorization of secondary metals while reducing energy use and GHG emissions compared to linear extraction models [11]. Despite its relevance, quantitative comparisons between conventional mining and urban mining remain limited, particularly for resource-producing countries such as Peru. Although Peru is a leading global supplier of copper, gold, and silver, it also faces growing WEEE generation and limited domestic capacity for advanced electronic waste recovery, resulting in the export of high-value fractions to specialized facilities abroad [12], [13]. Existing studies rarely assess international urban mining pathways under consistent methodological frameworks or consider the joint recovery of multiple metals required for economic viability. To address this gap, this paper presents a comparative carbon footprint assessment of three metal supply models, conventional mining (Business as Usual, BAU), recovery and reuse of mixed electronic boards (R&R), and recovery and reuse of mobile phone electronic boards (R&R-MP), based on a real transboundary case linking WEEE generation in Peru with advanced metallurgical recovery in Europe. By evaluating the combined recovery of gold, silver, and copper, this study provides evidence on the potential of urban mining to complement primary extraction and contribute to more resilient, lower-carbon mineral supply chains. 2. STATE OF THE ART 2.1 Metal Composition And Recovery Potential In WEEE The literature consistently demonstrates that WEEE, particularly end-of-life mobile devices, contains metal concentrations significantly higher than those found in primary mineral ores exploited by conventional mining. Studies by Kumari [11] and Gómez [14] report that one metric ton of end-of-life mobile phones can contain approximately 53 kg of copper, 141 g of gold, and 270 g of silver, values that greatly exceed typical primary ore grades (e.g., <5 g/t Au in conventional gold mining). This enrichment is even more pronounced in printed circuit boards (PCBs), where concentrations of up to 278 kg of copper, 678 g of gold, and 1.3 kg of silver per ton of PCB have been reported [14], [15], despite PCBs accounting for only 15–20% of the total device mass. This disproportionate relationship between mass and metal values constitutes one of the core technical and economic arguments for urban mining, supporting the concept of WEEE as a high-grade secondary resource. 2.2 Pre-Treatment And Metal Recovery Technologies For WEEE Due to their structural complexity, material heterogeneity, and the presence of hazardous substances, WEEE requires dedicated pre-treatment stages focused on dismantling, separation, and concentration of metal-rich fractions prior to metallurgical processing [16], [17]. At industrial scale, the most widely applied recovery routes are pyrometallurgical and hydrometallurgical processes. For copper recovery from electronic waste, pyrometallurgical routes typically achieve recovery efficiencies in the range of 40– 45%, while exhibiting high energy demand and elevated greenhouse gas (GHG) emissions [18]. In contrast, hydrometallurgical processes report recovery efficiencies exceeding 95–99%, metal purities above 99%, and energy consumptions on the order of 4.5 kWh/kg of recovered copper. More recent studies highlight the increasing adoption of hybrid pyro-hydrometallurgical configurations, which enable the simultaneous recovery of copper, lithium, nickel, and cobalt with overall efficiencies approaching 98–99%, while reducing energy intensity and associated emissions [19]. These integrated technologies are currently regarded as best available practices by leading international WEEE recovery companies.
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