Nippon Mining & Metals Co.'s copper smelter venture with Mitsui Mining & Smelting Co. may almost triple its planned investment to develop a Chilean mine that contains more reserves than forecast.

    Pan Pacific Copper Co., the venture, will spend $1.7 billion on the mine in Caserones, compared with $600 million proposed earlier, the companies said today through a Tokyo Stock Exchange statement. A 9 billion yen ($85 million) feasibility study on the project will start this month and end in December 2009, they said.

    Demand for copper, used in wires and cables, is being driven by China, the world's fastest growing major economy. Nippon Mining is focusing on mining more of its own ore and is also conducting feasibility studies at the Quechua mine in Peru.

    If the Caserones mine is developed, Pan Pacific Copper will produce 3.6 million tons of copper over 26 years, or about 150,000 tons a year, and about 3,000 tons of molybdenum a year, the statement said.

    Pan Pacific Copper said in November it would spend $490 million on the Quechua mine project, south of Lima.

    Mitsui Mining shares fell 2 percent to close at 252 yen on the Tokyo Stock Exchange today.