Innovative Extraction Processes Could Unearth Billion of Dollars of Nickel

Australian technology firm, Direct Nickel Limited (DNi) has teamed up with CISRO scientists in Perth to develop a commercially viable method for extracting nickel from low-grade ore.

The project has the potential to impact the industry on an international scale, which could translate to billions of dollars worth of nickel made available for processing.

Traditional sulphate ore bodies are depleting and thus, the focus is shifting to laterite and saprolite ores, which contain approximately 70 percent of the world’s nickel. The new extraction technology has been six years in development since DNi sought the patent for nitric acid recycling. At the same time the firm approached CISRO regarding a collaboration to develop the process for metallurgical processes.

How the process works

The process, developed by DNi and CISRO replaces sulphuric acid with nitric acid during the high-pressure acid leaching process. Nitric acid as opposed to sulphuric acid eliminates problems associated with waste treatment and disposal and therefore is a lot more cost effective.

Furthermore, nitric acid is far more aggressive than sulphuric acid and as such can extract nickel at a much lower pressure and temperature, eliminating the need for expensive titanium lined equipment.

From small scale testing the project has grown to a $5 million pilot plant with the ability to recover 95 percent of reagents for reuse, reducing operating costs while extracting the majority of the nickel and cobalt from the deposit.

The fact that acid can be captured and recycled is a huge plus point for both parties involved owing to the fact that it eliminates the major cost associated with sulphuric acid plants; the neutralization of acid waste.

Dave Robinson, a spokesperson for CISRO Perth says: “There’s probably billions of dollars of nickel in Australia that needs this type of technology to turn it into a commercially attractive proposition. There’s a vast ore body out there that the current cut-off grade for sulphuric acid processing is too high for.”

According to Robinson, current plants such as Murrin Murrin (north-eastern Goldfields) are processing about one percent nickel. “If we can lower that [cut off grade] to 0.7 or 0.75, then there is billions of dollars worth of nickel that’s available for processing,” he says.

Environmental benefits

The process doesn’t only mean that nickel extraction from low-grade ore will become an economically viable possibility; it will become an environmentally viable possibility as well. During the process all NOx gases are captured and converted to reusable nitric acid and any leach residue is mainly silicates with minor residual nitrate content. Furthermore any nitrates caused by the residue, break down to form usable nitrogen for plant growth and return to the natural Nitrogen Cycle.

Production of saleable magnesia solves the magnesium disposal problem experienced by HPAL operations. According to DNi the mass of waste residues is less than half that of HPAL processes due to minimal disposal of reagent and neutralising agents – and production of saleable co-products. This is a major advantage in high-rainfall tropical environments.

“In summary [the process is] a highly efficient and elegant solution to the world’s nickel supply problems,” states DNi.

As Robinson concludes, “You can change the value of what is in the ground in Australia.”

The next stage of the project is to build a 30,000 tonne per annum nickel plant to demonstrate full-scale production and DNi is currently seeking a partner to develop such a plant. CISRO has spoken out to confirm that it will continue to develop the extraction process for wider application in the mining industry. Watch this space.