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Better ways to recover metals needed for technology from #ElectronicWaste could benefit the #environment and human health
Published: December 3, 2024
"As if our tech consumption hadn’t pushed demand for these metals through the roof in recent years, COVID also helped to make it worse. The pandemic drove sales of new electronics, contributing to more waste as old equipment became obsolete. The change to work-from-home/hybrid working saw more purchases of laptops and mobile phones. People also saw the pandemic as an opportunity to upgrade their televisions and games consoles.
"This has made it all the more important to recover the crucial materials we need from e-waste. One response has been from the Royal Mint, which has opened a recycling plant to recover 450kg of gold from 4,000 tonnes of e-waste per year – potentially enough for around 13 million phones. The average smartphone contains around 34mg of gold, which accounts for over 60% of the value of the metal-based parts of the phone per device.
"The Royal Mint initiative is an important milestone towards adopting a greener approach to metal recovery from discarded hardware. The mint is using an ambient temperature process, which means that precious metals can be recovered at room temperatures rather than being sent to smelters. The same process also allows for the selective recovery of other metals from the waste, such as palladium, silver, copper, iron, steel and aluminium.
Toxic methods
"The Royal Mint initiative is important because the recovery of technology-critical metals from recycled electronics typically employs much harsher conditions. Waste electronics generally first undergo what’s called pyrometallurgy, the extraction and purification of metals involving the application of heat in a smelter. This is done to liberate the metals from their casings.
"Further purification – both for the Royal Mint and other recovery processes – is carried out using methods collectively known as hydrometallurgy. This uses water-based solutions to recover purer forms of the metal, but also produces harmful waste: strong acids, such as sulphuric acid or nitric acid, as well as a group of chemicals called lixiviants, which can include cyanides, may be used to dissolve materials.
"Further treatment is required before these substances can be safely discharged back into the environment. Not doing so risks significant environmental impacts like the reported 'cancer villages' in China, which some have linked to factories and polluted waterways.
"Also environmentally troublesome is what’s known as artisanal, or small-scale, #mining – involving individuals, groups or co-operatives, rather than corporations. This accounts for 12%-15% of the global mined gold supply, accounting for around 2,000 tonnes per year.
"This mining occurs in over 70 different countries. The UN Environmental Programme estimates that artisanal and small-scale mining involve 10 to 15 million miners globally, including 4 to 5 million women and children.
"The cheapest and simplest method of extracting gold from ores, as well as from waste electronics, involves using mercury. This involves boiling off the mercury, releasing toxic mercury vapour into the environment. This can significantly reduce the life expectancies of people exposed to the resulting pollution, as well as causing significant damage to local water-sources and to soil.
"The opening of the metal recycling plant by the Royal Mint is therefore beneficial for various reasons besides being relatively environmentally friendly. It will lead to fewer toxic metals going to landfill that could potentially leach out into water supplies, and it will reduce our reliance on artisanal and small-scale mining for gold, reducing pollution and the risk to human health."