The owner of the Queenstown mine where three workers died in the space of a few weeks is "disappointed" in a recent High Court decision.
Coroner Simon Cooper is investigating the Mt Lyell mine deaths of Alistair Lucas and Craig Gleeson, who died after they fell from a wooden platform in December 2013, and Michael Welsh, who died just weeks later in a mudslide.
Mt Lyell owner Copper Mines of Tasmania had applied for special leave to appeal against the inquest hearing the contents of a report prepared by mining consultant John Webber into Mr Welsh's death.
That appeal, which questioned Mr Webber's expertise, was thrown out by the Supreme Court in June.
CMT subsequently took the appeal to the High Court of Australia, and on Thursday, judges Michelle Gordon and James Edelman also dismissed it.
"This application for special leave to appeal does not identify any reason to doubt the correctness of the decision of the Full Court of the Supreme Court of Tasmania," the decision read.
"The application should be dismissed."
On Monday, a CMT spokesperson vowed the company would thoroughly cross examine Mr Webber and his testimony.
"The company [will] cross examine the consultant and challenge the consultant's report 'line by line' to ensure it did not mislead the coroner.
"Any stress the delays may have caused the family of Michael Welsh, who died as a result of the mud rush, was unfortunate but it was too important a matter to let go unchallenged."
In a previous report, Mr Cooper wrote that he believed Mr Webber's report to be "highly technical" and his expertise to be credible.