Rio Tinto is lowering expectations for its 2022 Pilbara iron ore shipments following two unplanned rail outages.
But the mining giant says it now has a pathway towards capitalising on a major undeveloped iron ore deposit in Western Australia.
Rio Tinto said on Tuesday its full-year iron ore shipments would be at the lower end of its guidance of 320 million to 335m tonnes following outages on its Yandicoogina and Gudai-Darri rail lines in the Pilbara.
An investigation into the derailment on the Gudai-Darri line is ongoing, the company said.
The 166km line opened this year, linking the new Gudai-Darri mine in WA with Rio's existing rail network in the Pilbara.
For the three months to September 30, shipments were down one per cent to 82m tonnes, while in the last nine months Rio shipped 234.3m tonnes - one per cent lower than a year ago.
While shipments were down, the miner noted iron ore production rose during the quarter.
Its production of 84.3m tonnes was up one per cent from a year earlier and up seven per cent from the second quarter.
Rio Tinto chief executive Jakob Stausholm said production improved quarter-on-quarter for most of the miner's sites, particularly where the company's safe production system had been implemented.
Rio Tinto also cut its forecast for refined copper due to issues with the smelter and refinery at Rio's Kennecott copper mine outside Salt Lake City.
Bauxite production was down due to equipment problems at its Gove operation in the Northern Territory.
Rio said while it has been four years since a fatality had occurred at a company-managed site, its third-quarter injury rate had deteriorated.
RBC Capital Markets analyst Kaan Peker described it as a "weaker-than-expected result driven by the aluminium and copper segments".
He titled his client note on the Rio update "operational concerns persist".
Rio Tinto announced on Tuesday it had a pathway to develop the Rhodes Ridge project in the eastern Pilbara, one of the world's largest and highest-quality undeveloped iron ore deposits.
The miner said it had struck a deal with Wright Prospecting, a Perth-based company controlled by descendants of mining entrepreneur Peter Wright, to modify their 50-year-old joint venture agreement covering the prospect.
Located 40km northwest of Newman in WA, Rhodes Ridge is estimated to contain 6.7 billion tonnes of iron ore - about a third of Rio Tinto's total resource base in the Pilbara.
The project had been mired in court battles for many years between Wright Prospecting and Gina Rinehart's Hancock Prospecting.
"Rhodes Ridge contains one of the biggest and best undeveloped iron ore deposits on the planet with proximate access to existing infrastructure," Rio Tinto iron ore chief executive Simon Trott said.
"We are very excited we have been able to strengthen our relationship with Wright Prospecting and have a pathway to bring this high quality resource to market."
Rio Tinto said it would begin planning how best to develop Rhodes Ridge, with a goal of beginning mining before the end of the decade, subject to relevant approvals.
At 10.28am AEDT, Rio TInto shares were up 0.5 per cent to $94.61.
