Businessman Clive Palmer's company Mineralogy has won a Supreme Court claim for $US150 million in unpaid royalties against two Citic Pacific subsidiaries over a Pilbara iron ore project.

But there is uncertainty over if and when that money will be paid, and the impact on the future of the Sino Iron project.

Justice Kenneth Martin today ruled Mineralogy's claim over $US149.4 million in unpaid royalties against Sino Iron and Korean Steel had been established.

However, he also found the claims by Mr Palmer's company against Citic — as guarantor for Sino and Korean debts — remained to be determined.

Citic had paid Mr Palmer $US415 million in 2006 as part of a takeover agreement of the project, which included Citic also paying two different forms of royalties to Mineralogy.

Citic has refused to pay the second royalty, known as Royalty B, prompting Mineralogy to make the $US150 million claim.

Citic argued the royalty payment was linked to the-then fixed benchmark pricing system for iron ore, but that was abandoned for the current spot price system in 2010 and so it should not have to pay the royalty.

But Mineralogy countered, saying the agreement with Citic made no mention of the benchmark system and a royalty sum could still be calculated from the different spot prices over the years.

Justice Martin accepted the agreement did not refer exclusively to the benchmark system.

"He accepted that the phrase referred to prevailing published prices for the two iron ore products which are still actively traded on a daily basis in the international iron ore market," the judgment summary said.

Justice Martin concluded a Royalty B payment rate could still be ascertained using the spot market price, and found Sino and Korean must "severally pay" Mineralogy the $US150 million.

But he added the "final position" as to Citic as guarantor of Sino and Korean's debts is to be the subject of "further submissions by the parties concerning Mineralogy's failure to date to formally plead out the written demands it had issued to Citic ... for it to pay the (Royalty B) amounts not yet paid to Mineralogy by Sino Iron and Korean Steel".

Potential lifeline for controversial businessman

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The court's decision means Mr Palmer could be owed hundreds of millions of dollars more over the future production life of the Pilbara project, in a major boost for the Queensland businessman.

Mr Palmer's business interests have taken several hits in recent years, the biggest of which was the collapse in 2016 of Queensland Nickel, which went into administration with $300 million in debts and left more than 800 people out of work.

Following Justice Martin's ruling, Mr Palmer tweeted he was "keeping the aussie (sic) flag flying to protect Australia's freedom".

A spokesman for Citic said the company would "carefully review the judgment and its implications for Sino Iron".

There will be another hearing to address the outstanding issues next week.