The company said the processing equipment, which includes an Outotec high-intensity grinding mill (HIGMill) and gravity concentration spirals, will help the plant facilitate sulphide ore treatment. Its target post-expansion is to reach 100,000oz per year with a minimum mine life of five years.

Commissioning of the facility is expected to occur during the March quarter of next year. Millennium is hoping to achieve overall recovery of 85% on average on a blended feed of oxide and sulphide ore.

Millennium CEO Peter Cash said getting the procurement process started for the expansion's equipment needs was important to its goal to deliver on its growth strategy.

"It will help ensure we meet out milestones," he said. "This is a very positive step forward for the Nullagine project as we gear up to unlock the potential of our extensive sulphide ore resource base and deliver a step-change in our mine life and production profile."

Nullagine, located 185km north of Newman, currently processes its ore at the two-million-tonne-per-year Golden Eagle carbon-in-leach ore treatment plant. Ore is delivered from several open pits to a 150,000t-capacity stockpile.