Indonesia's first alumina refinery has started commercial operations, with most of its output committed for export to Japan, as the country's push to add value to minerals domestically begins to bear fruit.

The refinery in Tayan, West Kalimantan, is one of the first mineral processing facilities to start operations since Southeast Asia's largest economy banned exports of unprocessed ores in January 2014.

The refinery - a joint venture 80 percent held by state-owned miner Antam and 20 percent owned by Japan's Showa Denko KK - is targetting an initial output of 150,000 tonnes of chemical grade alumina in 2015, Tri Hartono, corporate secretary at Aneka Tambang (Antam), told Reuters.

The plant aims to produce 300,000 tonnes of alumina a year from next year, consuming around 800,000 tonnes of washed bauxite, Hartono said, supplied by Antam's bauxite mines in the area.

Showa Denko has a contract to take 70 percent of the refinery's production capacity, he said, with the remaining 30 percent for the domestic market and markets outside of Japan.

Antam also plans to develop a smelter-grade alumina refinery in Mempawah, West Kalimantan, Hartono said. For this refinery, it is hoping to form partnerships with Indonesian aluminium smelter Inalum as well as a technology provider.

"We are hoping to partner with PT Inalum, because the smelter-grade alumina produced (could be used) as its raw material," he said. "We are also still looking for a technology partner overseas with experience in this field."

Development of the $1.7 billion Mempawah project will also rest on Antam's ability to secure funding through partnerships and from the government, he said.

Antam is hoping for a breakthrough in funding after its request for a 7 trillion rupiah ($551.40 million) equity injection - to help fund various projects including Mempawah, an anode slime processing facility and a nickel smelter in eastern Indonesia - was halved by parliament.

"Antam's financial structure is not great at the moment because the ban on raw material exports disrupted our cashflow," Hartono said. "If the government approves our equity injection proposal we have completed the feasibility study so this year we should be able to begin construction." ($1 = 12,695 rupiah)