Ardea to drive more value from ore via an 'ESG edge' at Kalgoorlie Nickel Project

Ardea Resources’ (ASX:ARL) latest metallurgical testwork has allowed the company to identify a pathway forward to getting more value out of nickel-containing ores at its Kalgoorlie Nickel Project, while minimising the amount of waste acid left over by traditional refining processes. 

Let’s dive into some background. Ardea is mining laterite-type nickel deposits, which require a more thorough downstream processing regimen which requires applications of liquid acids. 

In a traditional laterite-type nickel leach, ore is introduced under pressure and high temperature into a solution of sulfuric acid; nickel enters the solution, but iron and other unwanted materials do not. 

This acidic solution, containing nickel, is then further processed, requiring more purification and combination with other reactants until nickel sulphide precipitates. 

 The issue of sulfuric acid 

This process of turning nickel laterite into sulphide is environmentally risky (given the waste acid) and is typically relegated to countries like China where special economic zoning rules allow for the disposal of waste acid into waterways, something which just isn’t kosher in tier-1 jurisdictions. 

Ardea’s technical team has found a way around that problem: by using magnesite left over from first-stage processing, the company’s geotechnical team will be able to neutralise the sulfuric acid used, which would otherwise need to be treated with caustic or lime, posing more issues for disposal.

Under Australian law, acid must be neutralised before it can be disposed of, which comes at greater cost than is otherwise witnessed in less rigorous jurisdictions allowing for the disposal of acidic materials. 

For this reason, nickel sulphides are seen as a superior style of nickel mineralisation by many nickel explorers in Australia. In short, it's less onerous to process, and less loose ends are left over from a compliance point of view.

Decarbonisation angle 

Ardea also highlights that by using magnesite to neutralise sulfuric acid, the company can cut its emissions profile by foregoing truck deliveries of limestone to the project.

As an added benefit, Ardea’s metallurgy research suggests it can retrieve up to an additional 200,000 tonnes of additional ore to feed through processing plants by using this method, which it highlights ultimately means more potential nickel recovery at a low cost, making it economically viable. 

In this way, Ardea is effectively getting a higher value of nickel from its ore that would otherwise be wasted. 

Significant breakthrough: Management 

“The Feasibility Study for the Kalgoorlie Nickel Project’s Goongarrie Hub has been focussing on the metallurgy of [nickel laterite and sulphides respectively] to allow various mineralisation styles to be specifically matched,” Ardea’s MD Andrew Pekethman said. 

“[Our discovery of this] simple low-cost screening is a significant processing breakthrough.” 

In the background, Ardea continues to upgrade its JORC-compliant ore reserve at the project, as well as touching up mine design plans towards the view of an open pit operation. 

Environmental permittage documentation is being progressed, as well as a larger overhead Pre-Feasibility Study, which will incorporate Ardea’s novel approach to processing management. 

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