Solar panels floating on liquid waste: How a mine in Chile powers itself

Chile has found another use for dams that hold the liquid waste from massive copper-mining operations: power generation.

Calling it the first project of its kind in the world, Anglo American Plc has installed 256 photovoltaic panels at the tailings dam for its Los Bronces complex in Chile. The panels are floating atop the sometimes-toxic ground minerals and effluents blasted out of rocks dug up at the mine. The pilot project is expected to generate 150,000 kilowatt-hours a year and help power the operations there, the company said in a statement on Thursday.

While it’s not much electricity in the grand scheme of things, Chile Mining Minister Baldo Prokurica hailed the solar project as yet another example of how the country -- the world’s largest copper producer -- is leading the way in improving how miners treat waste. Chile was the first to ban so-called upstream dams, which are cheaper to maintain but have led to deadly accidents, such as the collapse of one at a Vale SA mine in Brazil that killed at least 180 people in January.

“We are advancing toward a more sustainable mining activity by actively developing new solutions and stimulating other ways of thinking and working,” said Patricio Chacana, vice president of operations at Los Bronces.

The panels at Los Bronces were specially designed to resist the extreme conditions of the Andes mountains where the mine sits. At 3,400 meters (more than 11,000 feet) above sea level, the area is constantly hit with snow and heavy rains. The panels can withstand winds of 210 kilometers (130 miles) an hour, according to the company.

Preserving Water
 

Another upside: Anglo said the panels will shield the liquid in its dam from direct sunlight, reducing evaporation by 80 percent and improving water recovery rates, the company said. Recycled water makes up about 45 percent of an operation’s total water demand.

Aside from the solar project, Chile’s government is also looking to start a pilot to monitor the operations of tailings deposits live, Prokurica said. Local communities would receive phone alerts should an emergency occur at one of the dams, he said. The country already regulates the minimum distance between urban centers and mining waste deposits.