Japan-based trading company Mitsui & Co. has signed agreements to acquire a 40% interest in the Rio Tinto-operated Rhodes Ridge iron ore project in Western Australia for $5.34bn (Y800.51bn).

The deal is expected to bolster Mitsui’s iron ore production capacity and long-term earnings base.

Wright Prospecting’s former 50% interest in the Rhodes Ridge Joint Venture (RRJV) has been restructured and separated into two newly formed entities separately controlled by its shareholders, VOC and AMB.

VOC Group holds a 25% interest in the RRJV through an entity named Rhodes Ridge Mining (No 2) and AMB Holdings holds its 25% interest through Rhodes Ridge Mining (No 1).

Mitsui will purchase VOC Group’s entire 25% stake in the RRJV for $3.34bn, with completion anticipated by the financial year ending March 2026, subject to regulatory approvals.

The second transaction involves a heads of agreement with AMB Holdings to acquire a 15% interest in the RRJV for $2bn, pending due diligence and definitive agreement.

Following these transactions, Rio Tinto will own 50% of the project, Mitsui 40% and AMB 10%.

Rhodes Ridge, situated in the resource-rich Pilbara region, is one of the largest undeveloped iron ore deposits globally, with an estimated 6.8 billion tonnes of mineral resources.

Production is scheduled to commence by 2030, with Mitsui’s annual equity share of production initially expected to be around 16 million tonnes (mt), potentially exceeding 40mt post-expansion.

Mitsui president and CEO Kenichi Hori said: “This investment, which exceeds Y800bn, represents the largest single investment in our company’s history. Rhodes Ridge is located in Western Australia, a region where we have been engaged in mining development since the 1960s, and where we hold the most expertise in relation to the iron ore business.

“This investment will boost the strength of our business foundation, which we have built up over the years. We are very familiar with this area of business, the location and the partners. Given these factors, our Board of Directors has unanimously decided that we should make this investment.”

This acquisition aligns with Mitsui’s strategic focus on Industrial Business Solutions, identified as one of the key strategic initiatives under its Medium-term Management Plan 2026.