How long before it will be profitable to mine landfill sites? © Getty Images

How long before it will be profitable to mine landfill sites?

It's hard to say for sure, but with precious metals and discarded electronics littered around our landfill sites, we could soon be sitting on a goldmine.

Asked by: John Loader, Leyburn

Advertisement

A growing number of firms believe that landfill mining could soon be economically viable. The idea is to plunder waste sites for resources like precious metals from discarded electronic equipment. Circuit boards contain small amounts of copper, tin and even gold. It turns out that a tonne of electronic waste contains as much gold as 17 tonnes of ore.

It’s hard to say definitively when landfill mining will become a truly commercial proposition. First, we need to crack the technology for efficiently harvesting valuable materials from waste. Various magnetic techniques already exist for removing ferrous – and even non-ferrous metals. But a US aluminium company called Alcoa is working on a method called fractional crystallisation for separating alloys from each other. I’d love to tell you how it works, but Alcoa owns the technology and isn’t giving anything anyway.


Advertisement

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.