The final remaining mine on the south Wales coalfield is to close within three years.
Tower was bought out by its workers in 1995
Tower Colliery, near Hirwaun, closed in 1994 but was bought and re-opened by its own miners in 1995.
It remained profitable, but it has been announced that coal seams being worked by Tower's 375-strong workforce will be exhausted in two to three years.
Tower chairman Tyrone O'Sullivan said it was possible that mining in south Wales could continue elsewhere.
Tower Colliery was closed in April 1994 after continued production was judged to be uneconomic.
Its own miners, however, were not convinced.
A group of 239 of them raised £2m by each contributing £8,000 of their redundancy money to buy the ownership of the colliery, which reopened in January 1995.
The mine has been run successfully by the company formed by the workers, but on Friday chairman Tyrone O'Sullivan, told BBC Wales that the colliery was now coming to the end of its life span.
He said: "Probably we'll be the only pit in the world to work its last remnants of coal.
"We've seen the early closures of other pits (but) we, in many ways, are celebrating.
"At least we've been allowed, through getting our own pit, to work these last remnants of coal from Tower.
"Many of us have been here all our working lives - my father was killed here in 1963, so it will always have a huge place in my heart."
Tyrone O'Sullivan said the Tower story could continue
Tower is the final colliery in south Wales' once-huge mining industry.
At its peak in the early 20th Century, dozens of pits lined the valleys of south Wales, with the coal being exported through the booming ports of Cardiff, Swansea and Newport.
The industry went into decline in the second half of the last century with about 20 remaining south Wales mines closing in the years following the 1984-5 miners' strike.
But Mr O'Sullivan said Tower's impending closure may not represent the final chapter in the story of mining in south Wales.
"We are hoping to go down to Aberpergwm (near Glynneath). There's a small mine there," he said.
"Perhaps we can develop that into a mine which will continue mining in south Wales.
"I don't think this is going to be the end of mining."
The Tower chairman added that the company formed by the Tower miners was likely to go on to redevelop the colliery site.
"We own 480 acres of land, we want to fetch that back into the use of the people of the valley," he said.
"I think housing, factories, lakes, streams - the Tower story will go on for many years."