Mining electronic waste for precious metals

Professor John Blacker and colleagues around the world are finding ways to reclaim valuable materials from discarded electronics.

On the outskirts of Ghana’s capital city, Accra, on the banks of the Korle Lagoon, is the Agbogbloshie electronic waste dump.

This huge 20-acre scrap yard — that’s about the size of eleven football pitches — is the country’s main centre for e-waste recycling. Surrounded by towering piles of computers, laptops, old phones, printers, cables and plastic components, many people live, eat and work on the site.

It is here, and at other similar sites, that some of world’s electronic waste ends up.

The UK alone generates 1.6 million tonnes of electronic waste a year, much of which is exported to low or middle-income countries, especially Ghana and India.

This e-waste usually arrives at landfill sites where it is processed by hand by e-waste workers who extract the materials they can sell on, such as copper and silicon. Without access to sophisticated recycling technologies, the workers have no option but to do this by hand: stripping cables, hammering out components, or using chemicals or heat. It creates dangerous working conditions, and the money the workers make is small.

Professor John Blacker of the University of Leeds explains:

“To separate the materials, e-waste workers have to burn components in open pots, or dip them in vats of acid. That results in toxic bi-products and smoke — and it’s rare that any protective equipment is ever provided. The acids and bi-products sometimes leach into soil and groundwater, which has a wider ecological impact on the whole community.”

On top of the environmental impact, the workers and their communities aren’t able to extract the most valuable parts of the waste they process.

Rare earth elements, like neodymium and dysprosium, and even precious metals such as gold, are used in electronics to give them certain properties and are correspondingly valuable.

Dysprosium, which allows phones to vibrate, can sell for £5,000 a kilogram, but is found in trace elements in a smartphone. Gold, which sells at about £40,000 a kilogram, is found in bigger quantities, but still just 34 milligrams per phone.

The difficulty of extracting these materials is not only due to the very low quantities involved. The technique also requires expensive processing equipment. Only a few companies in the world — in China, France, Estonia, Malaysia and the USA — are able to do this type of processing.

That’s something that Professor Blacker and his colleagues in Ghana, Tanzania, Uganda, India, Indonesia and at the University of Leeds hope to change, as part of a project funded through the Global Challenges Research Fund.

“We believe we can come up with a small-scale way of getting out those precious and rare elements,” explains Professor Blacker. “If we can make this technology at a low enough cost to be accessible to e-waste workers in Africa and India, this should help them to gain more value from the waste they process.”

Palm-size technology

Working with his colleague at the University of Leeds, Professor Nik Kapur, Professor Blacker has already developed a technology that could be adapted for this use. ‘Freactors’™ are small processing units — about the size of the palm of a hand — which can perform multiple chemical processes. They are made from inexpensive materials and are easily assembled and operated.

The process of separating rare earth elements can involve many different stages and the team hope to use the ‘Freactors’™ as part of the solution to the problem.
The Freactor (TM) is a small device developed by University of Leeds professors John Blacker and Nik Kapur

“Mixtures of rare earth metals can be separated with powerful solvents. We hope to apply our continuous separation technology and build a test system that will eventually cost in the hundreds, rather than millions of pounds”, says Professor Blacker.

This more cost-effective method would open up the technology to smaller companies and local authorities, allowing more income to be created from materials that would otherwise go to waste.

Alongside this, researchers have been engaging with e-waste sectors in Dar es Salaam in Tanzania, Mumbai in India, Kampala in Uganda and Kumasi in Ghana. They found that, as rare earth element or precious metal extraction is not currently practised, the technology has potential economic benefits for the community.

By building relationships with potential users of the new technology, the aim is to eventually test its effectiveness in real world conditions.

Professor Blacker says. “Our research has shown that this kind of extraction could help to improve working and living conditions in the communities who draw their livelihoods from e-waste recycling, create more wealth and job opportunities.”

This method could help the planet too. The recovered metals could potentially be recycled and used in new electronics, reducing the mining of rare earth metals, a process that causes extensive environmental damage and pollution.

And hopefully in the future it could also help the workers such as those in Agbogbloshie, by making dangerous and polluting processes a thing of the past.
The team involved in this research are:

  1. University of Leeds, UK: Professor John Blacker, Professor Nik Kapur, Professor Animesh Jha, Dr Chris Holt, Dr Katherine Norman
  2. Dar es Salaam Institute of Technology, Tanzania: Dr Consalva Msigwa
  3. Centre for Research in Energy and Energy Conservation, Uganda: Mary-Suzan Abbo
  4. Winneba College of Technology, Ghana: Dr Kwabena Gyimah
  5. Institute of Chemical Technology, India: Professor Vishnawath Haily Dalvi
  6. Institute of Technology Bandung (ITB), Bandung, Indonesia: Dr Saut Sagala
  7. Federal University Of Technology Minna, Minna, Nigeria: Professor Abiodun Musa Aibinu

Culled from University of Leeds. The University of Leeds was founded in 1904, and its origins go back to the nineteenth century with the founding of the Leeds School of Medicine in 1831. This paper was first published in 2021


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