Flotation recovery has exceeded 90% for several shifts turning out concentrate grades of more than 40% copper.

The underground crusher and conveyor system are also operating to design expectations.

The larger sub-level cave footprint and optimised Carrapateena mine design are expected to improve cave establishment and provide a ramp up to the 4.25 million tonne per annum run rate by the end of 2020.

Throughput rates are to be increased to target 4.7-5Mtpa from 2023.

OZ Minerals CEO Andrew Cole said while the mine produced first concentrate in December, the minerals processing plant was subject to further work by the construction contractors to complete final commissioning tasks during January and much of February.

"It is a credit to all concerned to see the mill reach nameplate throughput so soon after handover and concentrate being accumulated," he said.

The processing plant will continue to be tested and optimised through the first half of 2020.

Along with the mine production ramp up this is expected to drive progressively higher throughput and concentrate production through the second half of the year.