Copper production from the Prominent Hill operation in South Australia rose to 32,991 tonnes, up from 31,160t in the March quarter and 22,181t the same quarter of 2014.

The Malu underground mine was commissioned three months early, resulting in $A47 million in net revenue so far.

Gold production dropped to 24,790 ounces from 32,874oz in previous quarter.

C1 cash costs for the quarter rose to US75.3c per pound from 63.2c/lb in the March quarter due to lower gold production, while total production costs of $1.569/lb were only slightly higher than the $1.544/lb reported in March.

While costs are expected to be higher in the second half of the year, the company expects to better its full-year C1 cost guidance of 80-90c/lb.

The Malu open pit will end in 2018, but run-of-mine stockpiles from the pit will continue to be processed until 2022.

“At the end of 2018, our copper ore stockpiles will have between 30,000 to 40,000t of copper contained metal and 45,000-55,000oz of gold metal,” Cole said.

“Gold ore stockpiles will reach 450,000 to 500,000oz of contained gold metal.”

The strong half saw OZ’s cash balance jump 87% to $A410 million, with $125 million coming from the sale of its stake in Sandfire Resources.

Cole revealed the company was working on acquisitions, having already reviewed and rejected a number of opportunities.

OZ is looking at one asset in production, two under development, one at an advanced stage and one exploration project.

“It’s absolutely a global search,” Cole said.

Cole said the company would rather buy something than find it at this stage of the cycle.

“Spending money on grassroots exploration in today’s market doesn’t make much sense,” Cole told analysts this morning.

Shares in OZ dropped 1.6% to $3.75.