Officials at BHP Billiton announced they will sell a $1.5 billion, 15% stake in their Australian Jimblebar iron ore mine in Pilbara to two Japanese trading firms, Itochu Corp. and Mitsui & Co. Ltd.

Located in Western Australia—in one of the world’s most prolific places for iron ore—the mine is now 100% BHP-owned. Itochu will purchase an 8% interest for $8 million; Mitsui said it will pay some $7 million for a 7% stake.

The deal will tie Itochu and Mitsui’s interests across BHP’s Pilbara iron ore operations, ensuring the assets are run in a simplified and flexible manner, according to BHP representatives. To date, Itochu and Mitsui collectively own 15% of BHP’s regional mine, railway and port infrastructure. With BHP, the firms already jointly own three other Pilbara iron ore mines, providing the two 27.9 million metric tons (mt) in annual production, mainly exported to China.

BHP executives hailed the deal. “We are pleased to extend our successful, long-standing joint venture relationship,” said BHP Iron Ore President Jimmy Wilson. Pending regulatory approval is anticipated by Q3 2013.

Including shares of future production increases, according to BHP officials, both traders will secure annual output of more than 5 million mt—equivalent to 4% of Japanese demand, The Nikkei reported. Jimblebar will have an initial production capacity of 35 million mt annually, bringing BHP Pilbara capacity to a 100% basis of 220 million mt.

The latest investment, in addition, will see the investors priming exports to Southeast Asia, amid plans to build blast furnaces, according to The Nikkei. The proposed venture will bring BHP Billiton’s asset sale total since Q1 2012 to $6.5 billion, according to company officials. Part of the proceeds, they added, will offset lower commodity prices from slackening global economic growth.

Spot prices for iron ore delivered to China is now down 40% from a Q1 2011 peak following the global recession of 2008, analysts said. Steel production growth, however, is predicted to increase to an annual 2.3 billion mt by 2025—more than 1.5 billion mt in 2012—led by a Chinese rebound and expansion in Southeast Asia.