Lonmin [JSE:LON] plans to cut 4 100 workers at mines that have run out of profitable ore and are being closed.
The platinum producer has started a process that's required under South African labour law to carry out the workforce reductions, said Wendy Tlou, a spokesperson for the company.
The layoffs will come from six old mines that have run out of commercially viable ore. The cuts are part of Lonmin's plan to trim its staff and lower costs at its deep-level mines.
In 2017, the company said it would cut 12 600 workers over a three-year period.
Shareholders are voting this month on an acquisition by rival Sibanye Gold after the company struggled through years of losses and was forced to seek debt-covenant waivers from lenders.