Production at BMA's Norwich Park mine will cease today following the company's April decision to close the site.
In a statement today the Construction, Forestry, Mining, and Energy Union said it was still concerned about the uncertainty some of the mine's workers faced.
The comments follow a Fair Work Australia ruling that BHP Billiton failed to properly consult the mine's workers over their accommodation and whether they faced redeployment or retrenchment.
When it announced the mine's closure BHP said lower coal prices, high costs, and the impacts of last year's floods had made the operation unviable.
But the CFMEU said BHP was in the middle of the "biggest coal boom Australia has ever seen".
"This mine was operating when coal was $70/tonne and now it's selling above $200/tonne and up until this afternoon export-quality coking coal was piling up ready to be loaded onto trains," it said.
"The only thing that's changed in Norwich Park's fortunes is that the company is pressing ahead with its plans to de-unionise the coal industry in the Bowen Basin."
Norwich Park miners will today provide a guard of honour to employees finishing their last shift.
Image: ABC TV News