South African mining company Sibanye-Stillwater said on Monday production has started three months ahead of schedule at its Montana-based Blitz project, boosting its platinum group metals (PGM) production in the United States.

The project is expected to produce approximately 300,000 ounces annually by late 2021/early 2022, increasing total PGM production from Sibanye’s U.S. operations by more than 50 percent to around 850,000 ounces.

“The operations continue to deliver as anticipated and first production from Blitz is more than three months ahead of schedule,” CEO Neal Froneman said in a statement.

Work on the Blitz project, which began in 2010, is adjacent to the Stillwater mine and is expected to extend that mine’s underground infrastructure to the east of the current operations, the company said on its website.

Sibanye acquired sole U.S. platinum miner Stillwater, the largest primary producer of PGM’s outside South Africa and Russia, in May 2017 in a $2.2 billion deal.