Cleaner tech to wow at Gap

RESOURCE Mining has developed more environmentally friendly and cost effective technology to extract nickel and cobalt from its Wowo Gap site following successful trials of a new organic acid.
Cleaner tech to wow at Gap Cleaner tech to wow at Gap Cleaner tech to wow at Gap Cleaner tech to wow at Gap Cleaner tech to wow at Gap

The successful trials have used organic acid to extract nickel and cobalt from both the shallower limonite and deeper saprolite ores and provide a cost effective alternative to a standard high pressure acid leach process which uses sulfuric acid as the leaching agent.

The company said the new acid is bio-renewable, and is significantly less harmful to the environment and employees when compared to the acid previously used.

Test work undertaken by the company indicated leach rates are typically in the order of one hour to achieve maximum metal extraction.

The company also believes the new acid could save it some capital, as the new process is not high-pressure, suggesting the cost of each leach vessel could be significantly less than an HPAL plant.

Research conducted by the company in 2007 found the Wowo Gap saprolite ore contained large amounts of magnesium silicate so that under normal HPAL treatment the magnesia in these ores was preferentially consumed by the acid.

The research confirmed very high concentrations of sulfuric acid must be used to leach nickel from saprolite, and because sulfuric acid is the major consumable in an HPAL plant, excessive use has a negative impact on project economics if saprolite only was to be processed.

A 2008 feasibility study discovered the HPAL process was economically viable for the shallower but lower grade limonite ores and the system could utilise high magnesia saprolite ore to neutralise the sulfuric acid.

While these results were encouraging, the majority of the higher grade and deeper saprolite ore was unable to be processed and so in 2010 the company looked to science-based innovation using alternative leaching agents to find a solution.

Resource Mining managing director Warwick Davies said the new technology would lead to better extraction rates while minimising the impact of the bleaching process on the environment.

"The results are particularly encouraging because it has the potential to change the project economics from a development perspective and be better for the environment," Davies said.

"Our research confirmed very high concentrations of sulfuric acid must be used to leach the nickel from the saprolite and because sulfuric acid is the major consumable in an HPAL plant, excessive use has a negative impact on project economics if saprolite only was to be processed.

"Importantly, the new technology also allows metal extractions up to 70 per cent for nickel and more than 95 per cent for cobalt in the shallower limonite ores."

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