But Treasurer Jackie Trad, the acting premier, was dubious about the extent of the fall-out, and said Treasury was conducting its own modelling, with the details to be outlined in the upcoming state budget.

"I think that some of the claims made by both sides in relation to the impact both on coal export and on the state budget have been somewhat exaggerated," she said.

Queensland Resources Council chief executive Ian Macfarlane said he hoped Ms Trad was correct, but argued Treasury's predictions had been "extremely conservative".

"Treasury last year, in their predictions for royalty, turn out to be a billion dollars low this year, so in terms of their predictions, they've been way out so far," Mr Macfarlane said.

Ms Trad said she had been in "constant conversation" with Aurizon and the QRC over the draft ruling.

"I know that both parties have committed to sitting down... to further those discussions," she said.

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On a trade mission to Japan, Queensland Premier Annastacia Palaszczuk personally reassured Japanese Foreign Affairs Minister Taro Kono that there would be a "continuity of supply", and met with steelworkers, as part of her trade mission this week.

"I reassured him and the government that there will be continuity of supply, and how much we value the trade relationship that Queensland has with Japan," she told Seven News.

Japan is Queensland's second-largest trading partner, with the state last year exporting $7.4 billion worth of coal to the country.

Earlier this week, Ms Palaszczuk urged QCA and Aurizon to urgently resolve the issue, while Ms Trad resisted opposition calls for the state to intervene, arguing the QCA was the correct body to determine charges.

Meanwhile, Aurizon lost a tender to renew a seven-year contract with GrainCorp, which was due to expire in November 2019.

Aurizon was contacted for comment.

The Queensland coal sector generated $36.2 billion in export revenue in 2016-17 and delivered $3.4 billion in royalty payments to the Queensland government.