Chinese Scientists Develop Ultra-Efficient, Low-Cost Method to
Recover Gold from 10mn tonnes E-Waste
New method can extract precious metals from
old mobile phones, computers and home appliances in less than 20 minutes
A
Chinese research team has unveiled what it claims is the world’s most efficient
and cost-effective technology for extracting gold and other precious metals
from electronic waste, potentially transforming the fast-growing “urban mining”
industry. The new method can recover gold from discarded CPUs and printed
circuit boards in under 20 minutes at room temperature, achieving a gold
leaching efficiency of over 98 per cent and palladium recovery of more than 93
per cent.
Developed
by scientists from the Guangzhou Institute of Energy Conversion, the Chinese
Academy of Sciences and South China University of Technology, the technique
uses a self-catalytic leaching process based on a simple aqueous solution of
potassium peroxymonosulfate and potassium chloride.
Crucially, it requires no external catalysts, high temperatures or toxic
chemicals.
Treating
10kg of circuit boards yields about 1.4g of gold at a cost of roughly US$1,455
per ounce—less than one-third of current international gold prices—making it
the most economical e-waste gold recovery method reported so far. Compared with
traditional cyanide-based techniques, reagent costs are cut by over 90 per cent
and energy use by more than 60 per cent, while generating significantly less
pollution.
As
China produces more than 10 million tonnes of e-waste annually, the
breakthrough offers a scalable, environmentally friendly solution to resource
scarcity and pollution, reinforcing Beijing’s push to position urban mining as
a cornerstone of sustainable precious-metal recovery.
Chinese
scientists have unlocked a method to harvest gold from electronic waste at a cost
less than a third of the present market price.
This
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.
It
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.
Treating
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.
As
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.
Gold,
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.
Mining
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.
Recent
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.
To
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.
They
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.
The
ingenuity of the technique lies in its “self-catalysis” mechanism – the precious
metals act as catalysts to initiate and accelerate the dissolution process.
On
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.
These
oxidants then break down the metal atoms, allowing chloride ions to grab and dissolve
them into the solution for easy recovery.
The
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.
The
value of this study extends beyond impressive lab results – its economic and environmental
benefits highlight considerable application potential.
Compared
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.
The
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.
China’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.
Although
many companies operate in this sector, their scale and efficiency vary widely, indicating
substantial potential for improved resource recovery.
As
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.