The Lonmin operation of diversified miner, Sibanye-Stillwater, was one of the significant contributors to the company's earnings in the first half of the year, as the miner battled disruption linked to the Covid-19 lockdown.

The first half earnings, released on Thursday, showed that the asset, acquired in 2019, contributed R3.9 billion of the group's adjusted net income, with CEO Neal Froneman describing it as "profitable".

Annual value from Marikana had more than doubled from initial estimates of approximately R730 million per annum, to an estimated annual run rate of up to R1.85 billion in annual synergies by the end of 2020, according to the company.

"That is more than double what we had originally estimated," said Froneman.

"There is still an additional upside from future processing of Rustenburg ore, when we do make that decision to move it from the Anglo Platinum processing facility to our own, but we have not made that decision," Froneman added.

The PGM concentrate from Rustenburg is smelted and refined by Anglo Platinum under a toll processing agreement. Sibanye acquired Lonmin in a R4.3 billion deal finalised in June 2019.

Froneman said the Blitz mine development in the US was expected to be delayed by about 12 to 18 months, as the company has not yet brought back all the contractors to site, due to Covid-19 safety protocols and equipment delays. The US PGM operations contributing 36% of the group adjusted net income.

The Blitz Project, which is part of the Stillwater mine, started ore production in 2017 and was expected to shift into full production in 2021. Formed in 2013 as a gold producer, Sibanye has grown to be the world's top producer of platinum group metals, through a series of acquisitions locally and abroad.

The company declared an interim dividend of 50c per share.