The Mining and Energy Union (MEU) has been fined more than half a million dollars for intimidating and threatening conduct against workers — referring to them as "scabs" and "maggots" — at a central Queensland mine.

The Fair Work Ombudsman took the MEU to court in 2021 after claims of verbal abuse, intimidation and threats were made against workers at the Oaky Creek North coal mine, north-west of Emerald.

Fair Work claimed the MEU filmed workers and posted derogatory material on social media in 2017 during an industrial dispute where some workers refused to down tools.

The MEU and five then union officials have been forced to pay a combined $657,105 after the Federal Court upheld a breach of the Fair Work Act.

The MEU has been further ordered to pay $10,000 in compensation to one worker, who was verbally abused and subject to derogatory social media material as well as signs calling him a "scab".

The court found the Fair Work Act was also breached during the industrial dispute in 2017, by publishing a list of "Oaky North Scabs" on social media and not taking the post down until early 2018.

Justice Darryl Rangiah found the respondents' conduct was meant to intimidate the workers by way of "aggressive and offensive" language.

"The respondents' intent in engaging in such intimidating and threatening conduct was to bring about what they perceived to be a favourable industrial outcome," he said.

"They did so in circumstances where they at least ought to have known that such conduct was unlawful."

Fair Work Ombudsman Anna Booth said the significant court penalties affirmed the seriousness of breaching the law with respect to coercion.

"There is simply no place for unlawful intimidatory and threatening conduct against a worker choosing to go to work."