PERTH (miningweekly.com) – Copper/gold miner Oz Minerals has seen gold production surge and copper production decline slightly during the fourth quarter, as a gold-only ore trial in December delivered results.

Copper production from the Prominent Hill mine, in South Australia, fell to 32 636 t during the December quarter, compared with the 33 518 t produced in the September quarter, while gold production increased from 23 817 oz to 31 547 oz in the same period.

“Prominent Hill had an excellent year in terms of safety, production and cost reduction,” said Oz Minerals MD and CEO Andrew Cole.

“We’ve had a record year of production and even with the current state of commodity prices, Prominent Hill is generating very significant cash flows with healthy margins. Our focus in 2015, which was to become a lean business, has driven down our cost while improving our operational output and reliability. This sets us up for another strong year in 2016.”

For the full year, Oz Minerals delivered 130 305 t of copper and 113 028 oz of gold, at a total C1 cost of $0.70/lb.

For the quarter, C1 cash costs were recorded at $0.67/lb of payable copper, which was lower than the $0.74/lb reported in the previous quarter, mainly owing to the higher gold production.

Cole said that the success of the gold trial confirmed the ability of the Prominent Hill plant to efficiently process stockpiles of gold ore. The trial was indicative of the expected blend of ore that would be fed into the plant post 2020, when the openpit operation ceased production and Prominent Hill transitioned to an underground-only operation.

“The gold trial was very successful and demonstrates that our plant will be able to efficiently unlock the significant value in our gold ore stockpiles,” Cole said.

Meanwhile, shipments from Prominent Hill reached 73 369 t during the quarter, containing 37 091 t of copper and 29 870 oz of gold, as well as 223 822 oz of silver.