new studies to boost laterite production

New studies to boost laterite production
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Friday, 10 July 2009
Colin Jacoby -- MINING NEWS --

BREAKTHROUGH research into nickel laterite processing has shown that an improvement in the quality of slurry used in high-pressure acid leaching (HPAL) may boost nickel production, spelling good news for Australia’s small pool of laterite plays.

While making up the bulk of Australia’s nickel resources, nickel laterite ore bodies have been viewed with scepticism in the past.

Lower grade and much more difficult and expensive to process than their better off nickel sulfide cousins, laterite ore bodies have taken a back seat to sulfide production in Australia.

On top of that, laterite has become are real stumbling block for nickel miners what with BHP Billiton and Norilsk mothballing their Ravensthorpe mine and Cawse mine respectively in the past year, not to mention the production problems faced by failed Anaconda Nickel at Murrin Murrin in remote Western Australia.

However, there is some positive news for laterite plays with ongoing research conducted by the Parker Cooperative Research Centre for Integrated Hydrometallurgy Solutions finding that rheology – the way fluids perform under pressure – of nickel laterites could be improved during the HPAL process by reducing the viscosity of the slurry and increasing the pulp density through the HPAL autoclaves.

CSIRO Minerals senior research scientist Dr Goutam Das told MiningNewsPremium that smectite ores – nickel laterites commonly mined in Western Australia – has a high slurry viscosity and are difficult to pump into HPAL autoclaves.

“Smectite ores are basically a clay-based mineral and so it exhibits poor rheological behaviour,” he said.

“We have been able to reduce the viscosity of the smectite slurry by mixing it with coarser particles and other minerals which resulted in improving the pulp density of the slurry under different conditions.”

Das said results from the studies, which are being conducted through the Minerals Down Under Flagship, have shown an increase of up to 20% in pulp density.

“Of course, it will differ from one ore body to other as the mineralogy varies, even differs within same operation,” he said.

According to Das, a 1% increase in the density of the slurry could result in a 2-3% increase in nickel production that would positively impact on the company’s profits.

“For example, a 2-3 percent increase in nickel output on a nickel mine producing 30,000 tonnes per annum could result in a more than $A10 million increase in the company’s profits,” he said.

Research is also being conducted to see the impact of water quality on the nickel laterite slurries used in the HPAL process.

“In general, salt water has a positive impact in improving the viscosity [of the slurry] and will be lower compared to freshwater where viscosity will be higher,” Das told MNP.

“The processing of the ore body depends on quality of the water locally available, so we are investigating systematically to understand the effect of various salts present in the process waters on improving of smectite slurry rheology.”

Research on how drying the nickel laterite ore would improve its rheology is also being carried out.

“It is understood in one of the minesites that drying of the smectite ore has a beneficial effect on improving the rheology, however we haven’t looked at that yet,” Das said.

“We expect to conduct research on that later this year.”