Solid Energy has confirmed it will go ahead with a planned restructure which will see 185 employees and contractors be made redundant.
Solid Energy chief executive Dan Clifford said some changes had been made to the proposal following consultation.
Two fewer positions will be made redundant than originally proposed.
The company will now undertake a selection process to decide who will stay on at the mine. The process was expected to be completed by the end of July.
Engineers, Printing and Manufacturing Union (EPMU) West Coast organiser Garth Elliott said it was a "sad day for our miners".
"We knew it was coming, but it's still a heavy blow."
Miners would now be able to apply for voluntary redundancy.
"But there still aren't a lot of jobs out there on the West Coast and when that money runs out things will get tough," Elliott said.
The EPMU said mismanagement by Solid Energy's previous board had led to the current struggles.
"We hold the Government accountable for Solid Energy's current position, and for not addressing the high dollar or creating jobs in our region. Miners are now paying the price for the politicians' inaction."
Coal production will reduce by 500,000 tonnes, to 1.4 million tonnes per year.
When the company announced the proposal on June 6, it cited low international coal prices as the reason for the change.
- The Press