Most are unsightly and useless, and they may even be toxic. But the castoffs from 200 years of mining in regional Australia could be a golden opportunity in the rush for green energy.
A series of supply shocks has awakened the world to the value of critical minerals and rare earths. They are used in the production of lightweight but strong alloys, batteries, electric motors and resilient electronics and are vital for high-performance and miniaturised technologies.
But they’re hard to find, costly and dirty to extract and refine, and their supply and prices are immensely volatile.
“Some 70–80% of the supply of most of these minerals is controlled by just one country – China,” says Monash University associate professor Mohan Yellishetty.
But this doesn’t need to be the case. Rich reserves of these minerals sit – on top of the ground – right under our noses.
They’re usually in remote and regional Australia, amid mining boom towns that have seen better days. But those boom days can come again, says resources engineering expert Yellishetty.
Much of the environmental and economic cost of mining these minerals has already been paid. The explosives have been detonated, the drills have done their boring. The diesel has been burnt to haul the ore out of the ground. And it’s often already partially refined.
Why do this all over again if such easy pickings are available?
“If you look at Olympic Dam [in South Australia], which we have studied a few times, it could supply quite a big chunk – up to 40% – of the world’s demand for rare earths,” says Yellishetty. “But only if BHP is happy to recover them.”
Most rare earths and critical minerals are found paired with a more common metal. So we know where to look. Olympic Dam, for example, is Australia’s largest copper mine. But associated with copper are the elements yttrium, cobalt and tellurium.
“At present, no critical minerals are extracted,” Yellishetty says. “They all end up in tailings. So all the hard work of digging them out of the ground has already been completed. It’s just a matter of finding a business and legal model to refine them.”
Australia’s made a start, he adds.
Geoscience Australia’s $225 million Exploring for the Future project is surveying national mine waste sites to map their potential.
For example, the Hellyer gold mine in western Tasmania has some $1.5 billion worth of gold, silver, lead and zinc sitting in its tailings dams.
Century mine at Lawn Hill in Queensland’s Gulf Country has the potential to become the world’s fourth largest zinc mine – thanks to the discarded tailings.
Sometimes, the results appear to defy logic.
OneVictorian gold mine, Yellishetty says, at times produces particularly high concentrations of antimony. This is needed for ammunition, cables and enamels.
“This is where the relevant legislative/regulatory structure may have to be agile to account for these dynamics so we can get most of our mineral ores.”
And that represents a failing of state and national policies. There are no legal means of separately licencing the rights to recover such by-products. And exactly who owns and can access what on a disused mine is yet to be determined.
But moves are afoot to change this, Yellishetty says. A few bold miners and the Exploring for the Future project are identifying opportunities.
“There’s still a lot of nitty-gritty that needs to be worked out,” Yellishetty concludes. “But at least there are positive moves. It’s a matter of having something is better than having nothing.”
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