OceanaGold has enlisted the help of independent advisory, design and engineering consultancy Beca to reduce emissions at its Macraes gold mine in Central Otago, New Zealand.

Beca developed an Energy Transition Acceleration (ETA) study to provides a pathway to a greener future at the mine, which produced over 172,000 oz/y of gold and employs more than 600 people. Macraes is New Zealand’s largest mine.

“As participants in the New Zealand government’s ETA program, OceanaGold are focused on reducing their greenhouse gas (GHG) emissions at their Macraes site to not only improve the sustainability of their product, but also reduce their energy costs,” Beca said.

“That’s where Beca entered the picture. As program partners with the ETA, our industrial sustainability and engineering teams worked closely with OceanaGold management to develop an Energy Transition Accelerator study that identified a practical emissions reduction pathway for their business.”

The Macraes operation consists of a large-scale surface mine, an underground mine, and an adjacent process plant inclusive of an autoclave for pressure oxidation of the ore. Its annualised gold production is split approximately 75% to open-pit production and about 25% underground production.

Key opportunities for reducing the GHG emissions include harnessing waste heat recovery; fuel switching; solar lighting towers; electric elution hot water heating; battery-powered electric haulage trucks; and electrification of excavators.

“Taken together, these practical abatement measures can reduce emissions from the Macraes gold mine by a substantial 37%, whilst additional measures – such as the use of renewable energy sources on site – could increase this figure to 59%,” Beca said.

With the study now complete, Beca says it is ready to support OceanaGold in implementing the identified recommendations over coming years – with some of these options also applicable to its Waihi mine on the North Island of New Zealand.