Gina Rinehart's Hancock Prospecting has lost its final bid to claw back a stake in the huge Rhodes Ridge iron ore project in Western Australia's Pilbara region.
A 2010 court order forced Hancock to relinquish its 25 per cent stake in the project, increasing Wright Prospecting's interest to 50 per cent.
The order also honoured an agreement between Ms Rinehart's father Lang Hancock and his business partner Peter Wright in 1984 that involved the carve-up of their various mining assets.
An appeal by Hancock was dismissed in October last year but the company contested certain court orders. In February, the appeal against the orders was dismissed.
On Thursday, the full bench of the High Court of Australia refused Hancock's application for special leave to appeal.
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Hancock will also have to pay court costs.
Wright Prospecting issued a brief statement saying it welcomed the ruling.
"Throughout this matter and the previous matters in the Supreme Court of Western Australia and the Court of Appeal, Wright Prospecting's focus has been to enforce and protect its rights to 50 per cent of the Rhodes Ridge joint venture," the company said.
"The company is pleased that today's ruling upholds those rights and the original judgment."
Rio Tinto owns the other half of Rhodes Ridge, situated east of the mining giant's West Angelas operations and south of its Hope Downs joint venture with Hancock.
Rhodes Ridge has been the subject of legal battles before the Hancock and Wright stoush, with junior explorer Cazaly Resources beginning its valiant attempt to wrest control of the project from the three mining heavyweights in 2007.
Cazaly alleged the joint venture had "warehoused" the project for decades rather than developing it.
In 2010, the Supreme Court of WA said Cazaly had a case but the company hasn't pushed ahead with its challenge.
Separately, Hancock and Wright remain embroiled in another court stoush over three of the six Hope Downs iron ore tenements.
Wright seeks half of Hancock's 50 per cent stake, considering Hope Downs was jointly discovered by Lang Hancock and Peter Wright.
The $US1.6 billion ($A1.72 billion) Hope Downs 4 mine is set to become fully operational at the end of this month.
