Concept and background
The term grew from Professor Michio Nanjo's 1980s idea of treating accumulated urban waste as an above-ground mine. A tonne of mobile phones contains roughly 150-300 g of gold, far more than a typical tonne of gold ore (about 5 g). The UN Global E-waste Monitor 2024 counted 62 million tonnes of e-waste in 2022, of which only 22.3% was formally collected and recycled.
The process
- Collection: gathering discarded electronics through take-back systems.
- Dismantling and sorting: separating circuit boards, batteries and plastics, then shredding and magnetic or eddy-current separation.
- Refining: pyrometallurgy (smelting) or hydrometallurgy (acid leaching and electrolysis) to recover high-purity metals.
Benefits and limits
Urban mining can cut energy use and emissions compared with primary mining, secure critical metals and keep hazardous substances out of the environment. But collection rates are low, complex products are costly to dismantle, and informal recycling in developing countries harms workers' health. Extended producer responsibility schemes require take-back in many countries, including Korea.
References
- Baldé, C. P., et al. (2024). The Global E-waste Monitor 2024. ITU and UNITAR.
- Cossu, R., & Williams, I. D. (2015). Urban mining: Concepts, terminology, challenges. Waste Management, 45, 1-3.
- UNEP (2011). Recycling Rates of Metals: A Status Report. International Resource Panel.