That adds to thousands of planned job losses across the mining sector, due to infrastructure challenges and weaker commodity prices.
Kumba, a unit of Anglo American, said in December that it was curbing production to match the limited capacity at Transnet.
The state-owned rail operator has been hit by shortages of locomotives and spares as well as rampant cable theft and vandalism.
In a conference call on Tuesday, Kumba CEO Mpumi Zikalala said that the proposed job cuts, combined with the restructuring of head office roles which started last September, would affect 10% of the workforce.
The company said the restructuring is "necessary" for Kumba to remain competitive.
Its shares fell more than 5% following the announcement.
The news also comes after Anglo American Platinum on Monday (February 19) said it would cut 3,700 jobs in South Africa.
That's after a sharp decline in metal prices slashed annual profit by 71%.
Its competitors, Sibanye Stillwater and Impala Platinum, are also planning layoffs.
Job losses across South Africa's mining sector will likely put pressure on the ruling ANC ahead of elections due later this year.
South Africa's official jobless rate, measured at 31.9% in the third quarter of 2023, is among the highest in the world.
