Leach options emerge for Parks Reef

TWO alternative leach processes have been identified to treat near surface platinum group metals-rich oxide mineralisation at Podium Minerals’ Parks Reef project in Western Australia’s Mid West region.
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Two leaching processes show PGM promise.

The processes both use atmospheric leaching at low to moderate temperatures.
The two testwork programs were conducted with WildIP, a process technology company associated with former WMC CEO Hugh Morgan's Comet Minerals, and the Western Australian School of Mines.

WildIP developed a proprietary process for leaching nickel.

That process has shown potential for broader applications, which is why Podium worked with WildIP to test the process for PGMs. It was the first time the WildIP process was applied to PGMs.

The WildIP process uses ferric chloride in an electrochemical redox ionic substitution process to leach the target metals in a weakly acidified solution at low to moderate temperatures.

An important characteristic of the WildIP process is that the reagents are not directly consumed.

An acidic environment is created for the process and after the payable metals have been extracted the leach solution can be recharged with acid and reused.

The WASM testwork led to a sulphuric acid-chloride leach system that showed it could rapidly leach the tested samples under atmospheric conditions at temperatures between 70C and 90C.

It used sulphuric acid in saline process water, created with the addition of salt and calcium hypochlorite - pool chlorine - as an oxidant.

The process could be suitable for either a simple tank leach or vat leach configuration.

Both testwork programs demonstrated programs to leach the payable metals from the oxide mineralisation with high rates of metal extraction and fast leach times.

Futher testwork of both the WASM and WildIP processes are underway.

The scheduled WASM work is to test a sample of highly oxidised material from the lower PGM horizon, which is comparable to the sample most successfully tested by WildIP.

Ongoing WildIP work will further test the process under milder conditions to obtain more data of the potential of the process.

Podium Minerals' CEO Tom Stynes said the success of the initial leaching programs was exciting.

"The leaching process route provides an opportunity to maximise the value of the oxide mineralisation with the testwork achieving high rates of metal extraction plus the potential to produce a product in a form suitable for sale direct to metal refineries," he said.