Gold from Gadgets

The Royal Mint

The Royal Mint’s Tony Baker and Julian Cox explain to Adam Duckett how a solution in a beaker was transformed into a world-first chemical plant

WHEN you hear the words “Royal Mint”, I doubt your first association is “process innovation”.

Before I discovered that the UK’s maker of coins was installing a world-first chemical plant in South Wales – one that is now recovering gold from electronics waste – the Royal Mint conjured in my mind centuries-old tales of unmechanised production, cocktails of toxic chemicals, and cameos from some of the greatest heroes and villains from English history.

Picture the scene: Henry VIII is at the Tower of London, the mint’s historic home, and he’s turning red. People have started calling him Old Coppernose – behind his back of course – because in a desperate push to raise cash he’s had the Royal Mint debase the nation’s currency. The corruption is so extensive that only a thin layer of silver remains atop his copper-filled coins. Ashamedly, it’s rubbing off his front-facing portrait to reveal the reddish metal beneath.

And then there’s Isaac Newton. Having formulated his laws of motion, amid his groundbreaking work on optics and heat transfer, he’s serving as Warden of the Mint. And this is no ceremonial role. To sure up confidence in UK currency, Newton’s in disguise, sleuthing through the ill-lit taverns of 17th century London hunting down counterfeiters and eagerly bringing them to justice.

Let’s not forget William Foxley, a worker at the mint who in the 1540s fell asleep for a fortnight. It caused such a stir that Henry VIII visited to witness with his own eyes this “sleeping beauty” whom no one could rouse. Having woke from what is now thought to have been a coma brought on by exposure to heavy metals used at the mint, Foxley lived with no apparent lasting effects for another 40 years.

These lingering impressions of old, dirty practices are quickly put out of my mind as Tony Baker and Julian Cox talk me through how their new plant at the mint’s home in Llantrisant, South Wales works.

A greener route to gold

Baker, who is the director of manufacturing innovation, says the purpose of the project was to create a more sustainable source for the precious metals used by the mint.

“My role was to set up from scratch a brand-new project group of chemists, and chemical, mechanical, and electrical engineers to design and develop a full scaleup plant. All from chemistry that was very much in a beaker at the time.”

Cox joined as head of development two years ago, persuaded by Baker to come “join the adventure” and help establish the new processes required for the full-scale plant.

In short, the plant has the capacity to process 4,000 t/y of printed circuit boards (PCBs) removed from discarded gadgets like your unwanted phone or laptop. There’s a lot of value locked up in that volume of “waste”. Around half a tonne of gold, 1,000 t of copper, 2.5 t of silver, and 60 kg of palladium. Yet most waste circuit boards from the UK are exported and often smelted at high temperatures, recouping some of their value but also releasing emissions and dioxins if not done responsibly. There are hydrometallurgical recovery methods too, but these involve the use of toxic acids.

The mint is piloting a more environmental approach.

How it works