Oz Minerals announced that its board has sanctioned the AUD1.25bn ($960m) block cave expansion at its Carrapateena copper-gold mine in South Australia.

The Australian mining company has scheduled the start of the block cave decline early works in the fourth quarter of this year.

The Carrapateena block cave expansion project is expected to unlock the potential of the copper-gold mine to be a multi-generational, low quartile cash cost producing province, claimed the company.

It will boost production to 12 million tonnes per annum (Mtpa) and average copper production to approximately 110-120ktpa, while gold production will be ramped up to about 110-120koz.

Oz Minerals said that the block cave expansion has been integrated into the existing operations plan of the Carrapateena to take a whole of province development approach. This will help in simplifying planning, minimise execution threats, and maximise opportunities in value creation, said Oz Minerals.

As per the pre-feasibility study released by the firm in June 2020, the expansion project involves converting the lower part of the current sub level cave into a series of block caves.

Under the expansion project, the company is targeting block cave 1 to begin operations by 2026 and block cave 2 by 2038.

According to Oz Minerals, the integration and fast tracking of the block cave expansion will help in de-risking the Carrapateena Province progressively in its sub level cave ramp-up to 4.7Mtpa to 5Mtpa from 2023.

Besides, the expansion project is expected to considerably increase the reserve and mine life of the copper-gold mine.

Oz Minerals managing director and CEO Andrew Cole said: “Carrapateena capital expenditure now reflects Board approval to proceed with the Block Cave Expansion, previously deferred capital resulting from COVID-19 contingency planning and the ongoing focus of debottlenecking and increasing the sub level cave production rate to 5Mtpa.”

Carrapateena is an underground mine found in the Gawler Craton geological province, about 160km north of Port Augusta.

Oz Minerals, which approved the AUD916m ($701.5m) development of the Carrapateena copper-gold mine in August 2017, produced first concentrate in late 2019.

Meanwhile, the company revealed that it intends to take a final investment decision on the Prominent Hill expansion project in mid-2021.