Chinese team unveils world’s most efficient e-waste gold recovery tech

Chinese scientists have unlocked a method to harvest gold from electronic waste at a cost less than a third of the present market price.\nThis gold-mining method can extract precious metals from discarded central processing units (CPUs) in old mobile phones and computers and printed circuit boards (PCBs) removed from home appliances through chemical washing in less than 20 minutes.\nIt achieves over 98.2 per cent gold leaching efficiency from waste CPUs and PCBs at room temperature, along with a 93.4 per cent extraction rate for palladium while producing much less pollution than traditional methods.\nTreating 10kg (22lbs) of PCBs can yield around 1.4g (0.05 ounces) of gold at a total cost of about US$72, or US$1,455 per ounce, according to the researchers. This is the most cost-efficient method reported to date and makes e-waste gold recycling an incredibly lucrative business: in early January, international gold prices exceeded US$4,472 per ounce.\nAs China produces several million tonnes of e-waste each year, this technological breakthrough offers a potentially game-changing solution to both resource scarcity and environmental harm as Beijing positions urban mining as the future of sustainable precious metal recovery.\nGold, platinum, palladium and other precious metals are widely used in electronics, catalysts and jewellery due to their excellent stability, conductivity and catalytic properties. However, they are scarce and mining them often leads to habitat destruction and soil and water pollution.\nMining e-waste for precious metals is profitable and sustainable – a practice called “urban mining”. But existing methods often use highly corrosive or toxic chemicals that harm the environment and human health.\n\n\nRecent efforts to develop milder leaching techniques, such as photocatalysis, still rely on external catalysts, transition metal additives or extra energy – often making the process complex, wasteful and energy-intensive.\nTo tackle these challenges, a research team from the Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences and South China University of Technology came up with a new approach, outlined in a study published in Angewandte Chemie International Edition in November.\nThey proposed a self-catalytic leaching strategy that uses only a mixed aqueous solution of potassium peroxymonosulfate (PMS) and potassium chloride (KCl) to efficiently recover gold and palladium at room temperature without any external catalyst.\nThe ingenuity of the technique lies in its “self-catalysis” mechanism – the precious metals act as catalysts to initiate and accelerate the dissolution process.\nOn the surface of gold or palladium, PMS and chloride ions (Cl⁻) in the solution are activated; they react and generate two key species: singlet oxygen and hypochlorous acid.\nThese oxidants then break down the metal atoms, allowing chloride ions to grab and dissolve them into the solution for easy recovery.\nThe research team uncovered this mechanism through quenching experiments and spectroscopic analysis. Through systematic trials, they also determined the best amounts of chemicals to use for maximum efficiency.\n\nThe value of this study extends beyond impressive lab results – its economic and environmental benefits highlight considerable application potential.\nCompared to traditional cyanide methods, reagent costs are reduced by about 93.2 per cent, mainly due to the use of inexpensive and readily available PMS and KCl without costly catalysts. It uses far less energy – about 62.5 per cent less – by running at room temperature without needing extra power.\nThe process is also simpler and more environmentally friendly, reducing secondary waste like sludge. The leachate can be treated directly after reduction with ascorbic acid, concentration and calcination to obtain pure gold.\nChina’s annual e-waste volume has exceeded 10 million tonnes and continues to grow rapidly, according to data from the China Resources Recycling Association. Apart from discarded mobile phones and computers, household appliances such as televisions and refrigerators also contain circuit boards.\nAlthough many companies operate in this sector, their scale and efficiency vary widely, indicating substantial potential for improved resource recovery.\nAs reported by China Science Daily, this research provides a more sustainable and efficient recycling method for recovering precious metals from electronic waste. With its scalability, it can help reduce reliance on mining and promote the transition of the precious metal recovery industry towards greener and more advanced practices.\n