Prominent Hill to build second decline


OZ Minerals is planning to expand Prominent Hill’s underground production by building a second decline.

The new decline is forecast to lift production capacity of the underground operations by nearly a third, to between 3.5 to 4 million tonnes per annum.

It will run around 1.4 kilometres at a gradient of 1:7.75 and cost around $12 million.

The work will be carried out by Byrnecut.

 “Prominent Hill’s underground mine is proving itself to be an excellent asset and we want to invest in its future,” OZ Minerals CEO Andrew Cole said.

“By building a second decline, we will not only boost the underground’s capacity, we will significantly increase the efficiency of the whole operation and drive down future unit costs.

“Once the second decline is complete in the next two years, truck efficiencies in the underground will increase and we will see other major benefits in terms of ventilation and contingency planning.”

The decision to expand its underground operations follows the announcement of the winding back of operations above ground.

Last month OZ announced plans to reduce its workforce, and throughput, at its open cut operation.

“As we move into the later stages of the mine plan, the quantity of waste rock relative to the amount of ore will decrease, requiring less equipment to move material,” an OZ Minerals spokesperson told Australian Mining at the time.

“As a direct result of the equipment needs decreasing, there will be a reduced requirement for mining undertaken by our open pit mining contractor, Thiess. This reduction in the work undertaken onsite by Thiess will impact upon the number of people working at the mine as Prominent Hill transitions to an underground-only operation.”

The new focus on underground operations, and the creation of a second decline, will allow OZ Minerals to bring forward underground production during 2018 to 2022.

“In addition to building the second decline, we will spend approximately $4 million in 2016 to target resource to reserve conversion,” Cole added.