Sixty workers at Wales' last deep mine, Tower Colliery, have been given redundancy notices as the pit prepares to close within a year.
Tower hopes to save the jobs of 100 men with a new venture
The Cynon Valley pit was bought and reopened by its own miners in 1995, a year after it had shut down.
But depleted coal reserves mean it will finally close next January.
However, there are hopes of saving about 100 of its 375 jobs as Tower is in talks to develop the Aberpergwm drift mine in the Neath Valley.
Tower chairman Tyrone O'Sullivan confirmed that the 60 redundancies were part of the wind down of the mine.
He said he hoped men would be redeployed to the new venture at Aberpergwm.
"The pit is coming to an end in January," he said. "In June we have to slim down."
Tower has been a success since it was revived by its staff as every other deep mine in the once booming south Wales coalfield closed.
Dozens shut after the 1984/85 miners' strike, but some 240 Tower workers were allowed to buy it after raising £2m with their redundancy payouts.
Despite the impending closure, however, Mr O'Sullivan said last month Tower workers were celebrating as they had been allowed to dig out "these last remnants of coal".
There are still workable reserves of coal at Aberpergwm, and Tower miners will vote on whether to form a joint venture.