Dec.14 (Bloomberg) --Antofagasta Plc's (ANTO) board approved the $1.3 billion Antucoya copper project in Chile, which it says may boost the company's total output of the metal to 800,000 metric tons by 2015.

Japan's Marubeni Corp. (8002) will become a 35 percent owner in the project for $350 million, London-based Antofagasta said in a statement to the London Stock Exchange today. Marubeni is a shareholder in Antofagasta's Los Pelambres, Esperanza and El Tesoro mines in Chile.

Antofagasta is "confident" about long-term copper demand, Marcelo Awad, chief executive officer of the London-based company's mining division, said in the statement. The company, which operates four copper mines in Chile, has a "strong pipeline" of projects to supply growing demand for the metal, he said.

Antucoya will produce 80,000 metric tons a year of refined copper by dissolving the ore in acid, using a process known as heap-leach, the company said. Antucoya is located 45 kilometers (28 miles) away from the company's Michilla copper mine in Chile's Atacama Desert.

Copper fell 2.4 percent to $3.3595 a pound at 8:26 a.m. in New York. Prices have fallen 24 percent this year because of concerns of a slowdown in the global economy.

Antofagasta expects its total output this year to reach about 640,000 metric tons, Francisco Veloso, vicepresident of corporate affairs, said Dec. 6.