BHP's Olympic Dam mine has been hit again, with a mill breakdown setting back production on site.
The Svedala mill, which is the largest of the three on site, suffered an electrical failure late last month, according to The Australian.
"A complete diagnostic review was undertaken and revealed damage to the motor stator coil," BHP said.
"The repair and remediation plan is being developed and the company can confirm the mill will be out of service for approximately six months.
“BHP Billiton estimates a reduction in copper production of between 60,000 and 70,000 tonnes, with the majority of the loss anticipated this financial year,” the miner said in a statement.
It expects a return to full production by the end of the September quarter.
In regards to workers on site, BHP stated it is "working on how best to mitigate the impact this will have on our operations and we will communicate directly with employees and contractors as soon as we can".
This is the second major mechanical failure at the site.
In 2009 Olympic Dam saw a hoist failure, which caused a skip loaded with ore to fall down its primary Clark Shaft.
As the loaded skip fell it caused another on a linked cable to fly up the shaft, damaging the headframe, and slashing production by 75 per cent during repairs and cost the company around US$115 million in idle capacity costs.
The most recent electrical fault came only a day before BHP announced job cuts at Olympic Dam, and a fortnight before an accident at the site claimed life of a worker on site.