Abstract:

Technological innovations have led to an unprecedented production of electrical waste. As a result, e-waste has become the fastest growing component of municipal solid waste stream. With a near doubling in just 16 years, the global volume of e-waste is expected to reach 74.7 million metric tons by 2030. In addition, the Americas produced 13.1 Mt of e-waste by the end of 2022 with only 9.4% recycled. The value of metals lost in the 180 kt/year of Canadian e-waste can be estimated at over $CAD 550 million.

Classified in different categories, mobile phones constitute the most concentrated fraction of strategic metals in electrical waste. Thus, these devices are a boon for precious and strategic metals (rare earths, gold, silver, nickel, etc.). In this new circular economy paradigm, it is imperative to find ways of recycling these elements.

This research project has developed a hydrometallurgical process (selective acid leaching, solvent extraction, electrowinning, precipitation) that recovers different groups of metals of interest:

Over 79% of the rare earths were recovered as oxides, with a purity of 91%, for a yield of 93%;
100% of the copper is solubilised and recovered by electrowinning followed by precipitation of the nickel in oxide form;
100% of silver and over 72% of gold are solubilized.

Keywords: Electrical waste, spent mobile phone, recycling process, precious and strategic metals, acid leaching, solvent extraction, electrowinning, precipitation, circular economy, sustainability.

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Dr. Lan-Huong Tran