PERTH (miningweekly.com) – Gold miner Newcrest Mining on Friday revealed that its Cadia East operation, in New South Wales, would require a capital investment of some A$25-million to rehabilitate and upgrade the mine following a seismic event in April.

The New South Wales regulator placed Cadia East under a prohibition notice on April 14, prohibiting Newcrest from extracting ore in its Panel Cave 1 and Panel Cave 2.

No injuries were sustained during the seismic event.

Newcrest said on Friday that damage to the Cadia East underground mine infrastructure was minimal, with no permanent damage detected. However, the miner said it planned to increase the dynamic ground support capacity around known fault structures and rehabilitate ground support in areas impacted by the seismic event.

At Panel Cave 1, work on rehabilitating ground support has started, and subject to the lifting of the prohibition notice, the Panel Cave 1 will restart operations in the first quarter of 2018.

Work has also continued on rehabilitating and upgrading the ground support at Panel Cave 2, and it is currently assumed that the operation will restart ore production in the first quarter of 2018, subject to the lifting of the prohibition notice.

Work to restore Panel Cave 2 to production has been prioritised, while the remainder of the ground support upgrades are completed at Panel Cave 1 and other areas of the mine.

Newcrest currently has ten trucks conveying around 65 000 t/d of ore to the processing plant from the low-grade Cadia Hill stockpiles, with the ore being processed at a recovery rate of about 70%.

The gold miner has also identified a further 20-million tonnes of economically viable stockpile material available for processing. Furthermore, work has started to recommission the Ridgeway sub-level cave, with first ore expected in June this year.

Newcrest expects there to be some 600 000 t of accessible ore, at a grade of 0.35 g/t and 0.30% copper.

Subject to the lifting of the prohibition notice, Newcrest would produce between 650 000 oz and 750 000 oz of gold in 2018.

Meanwhile, the miner noted that a feasibility study on the proposed expansion of the Cadia processing plant has been completed; however, approval of the study is pending while the miner focuses on finalising remedial work at the Cadia operation.