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Chile's Copper Miners Battle Hostile Elements

August 25, 1985|JAMES L. ROWE JR. | The Washington Post

SANTIAGO, Chile — "Look at everything we do here. All to make a product with less value per pound than chicken," said Pedro Bolt, general manager of the Chilean state copper company's Andina division.

Workers at Andina's two mines--one a surface operation, the other below ground--must battle snow, bitter cold and the isolation that come with being nearly three miles above sea level in one of the most rugged patches of the Andes Mountains.

The surface mine, called Sul-Sul or South-South, is the highest copper mine in the world, nearly 14,500 above sea level, Bolt said. But to reach the "surface" ore, Andina miners had to remove nearly 130 feet of glacial ice that covered it--a process that took several years. They can work at the surface mine only nine months of the year.

The subterranean mine at Andina poses different, but also formidable, challenges. The top shaft of the underground mine goes straight into a mountainside nearly 12,000 feet above sea level. The ore mined from that shaft must be dropped nearly 1,800 feet to processing facilities about 10,000 feet above sea level.

Heavy Indebtedness

But despite the hardships, the mines have become an increasingly important resource for the cash-starved nation. With $20 billion in foreign debt, Chile relies upon copper for about half of its export earnings.

Andina--31 miles from Santiago as the crow flies but twice that distance by car--produces more than 100,000 tons of copper a year, about 10% of the production of Corporacion Nacional del Cobre, or Codelco, as the state copper company is commonly called.

A world copper glut caused by growing production and declining use has spelled low prices for the last three years. Copper that once fetched 90 cents a pound or more is selling for less than 70 cents today.

Despite the risks and costs of extracting copper ore among the perilous peaks of the Andes, Andina is among the most efficient and lowest-cost copper mines in the world, according to Patricio Guajardo, operations manager at Andina.

Chilean efficiency is due in part to the richness of the ore vein. The ore averages about 1.5% copper--the open pit ore is about 1.8% and the subsurface ore is roughly 1.2% copper, Bolt said.

But Guajardo said Andina achieves a substantial energy saving as well because the mine relies on gravity to move the ore from the point of extraction through the processing facilities to the shipping docks in Saladillo.

The vast grinding and processing facilities that transform ore that is 1.5% copper into a concentrate that is 30% copper are housed within a mountain cavern. The concentrate is piped 13 miles underground to the mining town of Saladillo, where eventually it is shipped by truck or rail to the Pacific port of Ventatas.

Energy Costs Jump

Energy costs rise dramatically when the drilling is down into the earth and the ore must be hauled to the surface and transported from one processing stage to the next.

U.S. copper producers may agree with Bolt's assessment of the relative value of the metal and chicken. "All you need to make a chicken is an egg and some corn," Bolt lamented.

But U.S. producers have fought hard to keep a lid on the amount of Chilean copper that finds its way into the United States--although last year President Reagan rejected controls on copper imports.

The subsurface mine is a product of U.S. technology. Cerro Corp. opened the facility in 1970 after three years of preparation. In 1971, the Marxist government of Salvador Allende nationalized Andina. Allende was murdered in a military coup in 1973, and three years later the mine became one of four divisions of the newly created Codelco.

The copper deposits at Andina long had been known to Chileans. The tips of the rich ore veins first were noticed on mountain outcroppings as long ago as 1850.

Devised Block Caving

But reaching the ore through the narrow, steep gully that is the Rio Blanco Valley and dealing with massive snowfalls proved insurmountable until Cerro devised a method of mining called block caving and figured out how to move the extracted ore through a subterranean tunnel.

That tunnel, which stretches about three miles underneath mountains, ends in the large cavern where the grinding, crushing and concentrating facilities are housed.

In the cavern, the ore is crushed, then ground into a wet powder by massive rotating drums. The powder is put into flotation tanks that use chemicals and agitation to produce a copper concentrate foam that bubbles over the side of the tanks and is collected, thickened in drying tanks and piped to Saladillo.

The waste material, or tailings, in the bottom of the flotation tanks also are thickened and piped to dammed-up valleys near the plant.

The surface mine, opened two years ago, has boosted capacity at Andina significantly. By the end of this year, it will enable Andina to process 28,000 tons of ore a day--twice the production of the subsurface mine alone.

Coping With Weather

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