Cleaner copper

AN AUSTRALIAN company is on the verge of commercialising a process that could unlock some mineral deposits previously thought uneconomic.
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Noel Dyson

It is called the Toowong Process and while it may lead some to recall a film with Patrick Swayze, Wesley Snipes and John Leguizamo in drag, it is actually something that could make make a big difference to copper miners.

Actually, speaking of films involving the late Patrick Swayze, it is hard to fathom the thinking behind the suggestion to remake the cult classic Road House with Ronda Rousey. That’s right, the same Ronda Rousey that lost her bantamweight belt in Australia on the weekend.

The Toowong Process actually refers to the Brisbane suburb and is from Core Resources – the same laboratory company that had a role in the Albion Process.

Yes, that is another process named for a Brisbane suburb. The Glencore-owned technology uses a combination of ultrafine grinding and oxidative leaching at atmospheric pressure to treat sulphides.

With the Toowong Process the aim is to remove deleterious elements from the copper at the mine site. These are elements such as arsenic, antimony, mercury and tin.

The patented process has already gone through a pilot stage and Core Resources is looking to pursue commercialisation opportunities.

It has also been named a finalist in the Australian Innovation Challenge awards.

The Toowong Process is the only mining finalist in its category.

Normally copper with these sort of elements bound up will be sent to the refinery for it to sort it out.

That leaves the refinery with the problem of dealing with them and can create a host of environmental problems there.

In some cases the material cannot be treated by the refineries because the levels of things such as arsenic are too high. In other cases the revenue returns from the refinery are much lower – possibly even making mining uneconomic.

These deleterious elements are a problem for mines such as Tampakan, Tempang and Wafi-Golpu.

Core Resources business development manager David Walker said the Toowong Process was a hydrometallurgical process that was essentially a largely self-sustaining alkaline leach.

The reagents are either generated from the concentrate in situ in the leach or recovered downstream and recycled.

The leached arsenic is fixed using standard technologies into a stable, non-toxic form.

So what becomes of this arsenic?

Walker said it was put back where it came from.

While that may not sound like the most environmentally friendly approach, he argued it was a lot better than the problems the arsenic could cause coming out of the stacks of a refinery.

Besides, the fixing technology makes the arsenic much more stable than it was when bound up in the mineral.

So what of the tin and the mercury?
 Walker said those too would be stabilised and returned to whence they came.

Sure there could be some value in the tin and mercury but the quantities are often too small to be commercial and these mines are focused on copper – not tin or mercury.

It has taken about six years for the Toowong Process to get this far.

Work started on it in 2009.

Three years ago Core designed, built and operated a $4.5 million pilot scale demonstration plant at its Queensland headquarters.

That plant treated 1.2 tonnes of concentrate from Tampakan over 34 days.

The plant stripped more than 90% of the arsenic from the concentrate at steady state conditions.

That lowered the arsenic grade from 1.1% to 0.1% and produced a cleaned copper concentrate that was suitable for sale.

Tampakan was the mine the Toowong Process was originally developed for. Back then it was an Xstrata-owned operation.

Core traces its heritage back to the old MIM, which was swallowed up by Xstrata and, subsequently, became part of Glencore.

Mineralurgy senior principal consulting engineer called the process a potential “win-win” because miners could use it to treat ore from existing operations that was high in arsenic or develop deposits containing arsenic.

“Smelters will receive ‘clean’ copper concentrate, minimising the problem of disposing of toxic wastes and residues that is become a major issue for operations even in China,” he said.

JK Tech’s professor David Way said the Toowong Process could “unlock sites throughout the world that are currently considered unviable mineralisations for sustainable mining”.

Core is weighing up options to commercialise the technology.

“We’re interested in licensing the technology to projects that want to use it,” Walker said.

 

“Alternatively there may be a large engineering group that maybe wants the technology for itself.”