Producing nickel and cobalt at Murrin Murrin

We are wholly owned by Glencore, one of the world’s largest global diversified natural resource companies. Our Murrin Murrin operations in Western Australia’s north-eastern Goldfields mine, process and refine nickel and cobalt to produce LME grade metal briquettes on site.

There are several steps involved in the process of extracting and processing nickel and cobalt from the ore, some of which are highly complex.

Our process plant consists of High Pressure Acid Leaching (HPAL) technology and a Refinery.

As an owner-operator, we also run our own utilities on site which incorporates:

• a 90 Megawatt (MW) power station (including steam and gas turbines)
• a 4400 Tonnes Per Day (TPD) acid plant (one of the largest in the southern hemisphere)
• a 6 Tonnes Per Hour (TPH) Hydrogen Sulphide plant
• a reverse osmosis water treatment plant which draws from our bore fields.

The laterite ore mined at Murrin Murrin is recovered through through shallow, open cut mining methods and transported via multiple roads to the Murrin Murrin hydrometallurgical processing plant where it is delivered to the run of mine (ROM) pad.

Here, the ore is sorted according to grade, crushed and blended to ensure consistent feed into the plant’s ore feed preparation circuit.

The ore is then mixed with water to form a slurry for processing in the HPAL circuit. The HPAL circuit consists of four titanium lined autoclaves, each the size of a small submarine.

The nickel and cobalt is leached out of the ore slurry, and into solution, by raising the pressure up to 44 atmospheres and mixing it with highly concentrated sulphuric acid at a temperature of 255 degrees celsius.

This generates substantial quantities of heat, which is recovered and then used to pre-heat incoming slurry.

Once the nickel and cobalt have been leached and are in soluble form, they must be separated from the residue waste material. This solution is "washed" to remove the waste residue, allowing the valuable nickel and cobalt solution to move forward for further processing, and the residue to be neutralised for tailings disposal as inert waste.

Leached ore solution now passes into the neutralisation circuit where calcrete is added to neutralise the acid.

The solution is then passed into the mixed sulphides precipitation circuit, where hydrogen sulphide gas is added to convert the solution into a mixed nickel and cobalt sulphide precipitate.

The mixed nickel and cobalt sulphide enters another autoclave where pure oxygen converts the solids from a mixed sulphide into a metal sulphate solution. Impurities such as iron and zinc are then removed, before the cobalt and nickel are separated using solvent extraction.

The nickel sulphate solution then enters six parallel autoclaves, known as the hydrogen reduction circuit, where the hydrogen is added, nickel metal is precipitated and then separated from the nickel free liquid stream. The nickel powder is then dried before entering the final processing stage.

The powder is formed into a pillow-shaped briquette, sintered in a furnace and then packaged for transportation.

The cobalt sulphate solution from solvent extraction follows a separate processing path which is similar to the nickel processing path but on a smaller scale, producing cobalt briquettes.

Learn more about the nickel and cobalt production process used at Murrin Murrin.