American Chemical Society, Environmental Science and Technology, 13(49), p. 7981-7988, 2015
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In recent years, recovery of metals from electronic waste within EU has become increasingly important due to potential supply risk of strategic raw material and environmental concerns. Electronic waste, especially a mixture of end-of-life electronic products from a variety of sources, is inherently with high complexity in composition, phase and physiochemical properties. In this research a closed-loop hydrometallurgical process was developed to recover valuable metals, i.e. copper and precious metals, from an industrially processed information and communication technology (ICT) waste. A two-stage leaching design of this process was adopted in order to selectively extract copper and enrich precious metals. It was found that the recovery efficiency and extraction selectivity of copper both reached more than 95% by using ammonia-based leaching solutions. A new electrodeposition process has been proved feasible with 90% current efficiency during copper recovery and the copper purity can reach 99.8 wt.%. The residue from the first-stage leaching was screened into coarse and fine fractions. The coarse fraction was returned to be re-leached for further copper recovery. The fine fraction was treated in the second-stage leaching using sulphuric acid to further concentrate precious metals which could achieve a 100% increase in their concentrations in the residue with negligible loss into the leaching solution. By a combination of different leaching steps and proper physical separation of light materials, this process can reach closed-loop recycling of the waste with significant efficiency.