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 pyrohydrometallurgical 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. 2.3.Carbon footprint assessment of WEEE recovery Life Cycle Assessment (LCA) literature consistently shows that metal recovery from Waste Electrical and Electronic Equipment (WEEE) delivers substantial greenhouse gas (GHG) reductions compared to conventional mining. Under cradle-to-gate system boundaries, recycling and reuse pathways typically avoid between 0.85 and 1.14 tCO₂eq per ton of WEEE processed, primarily by displacing energy-intensive extraction, beneficiation, smelting, and refining stages required in Business as Usual (BAU) metal production [20]
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