According to Central Queensland News, the union has taken the matter to the Fair Work Commission.
“A hearing was held yesterday but the tactic could delay workers from knowing their fate for up to two weeks,” the newspaper reported on Tuesday.
A Rio spokesperson said the company acted in accordance with the Fair Work Act over the job cuts.
"Our focus remains on providing support for the employees who are affected by these changes," the spokesperson said.
While the FWC website is yet to show any documentation, a Rio spokesman told International Coal News that the commission threw out CFMEU’s case against Kestrel in a subsequent hearing on Tuesday night.
It is a good result for Rio as redundancy matters before the FWC can drag on for many months.
Last week the FWC finally advanced a CFMEU case against Peabody’s North Goonyella longwall mine, also in Queensland, to the arbitration phase.
This action dates back almost 12 months to October 25, 2013, with CFMEU claiming that the mine did not meet its obligations to consult with it over the 30 mine workers made redundant in August 2013.