26 de agosto de 2014 / 16:53 / hace 3 años

Codelco begins using bacteria to make low-grade ores profitable

SANTIAGO, Aug 26 (Reuters) - Bioleaching technology that uses bacteria to extract copper from low-grade mineral is ready after years of development for use in Chile, potentially boosting production at world No. 1 copper miner Codelco as it seeks to squeeze more metal out of tired ores.

Bioleaching uses bacteria to obtain copper from sulfide ores, which with current technology are usually considered unprofitable and left unprocessed.

BioSigma, a joint venture between Chile’s state-run Codelco and Japan’s JX Nippon Mining & Metals, has been developing the technology over the last decade. It will use it to treat sulfides at Codelco’s Radomiro Tomic mine in northern Chile after successful trials, executives from the venture told Reuters.

Codelco is battling to maintain production levels against a backdrop of falling ore grades at its aging mines, a sliding copper price and rising costs.

By using bioleaching, the company can turn around a drop in production at Radomiro Tomic, said Fidel Baez, Codelco’s vice president of development.

Trials are also taking place at Codelco’s El Teniente and century-old Chuquicamata mines, said Baez.

MORE REFINED COPPER

Conventional acid leaching methods don’t work with sulfides or only at high temperatures, adding to already expensive energy costs.

Types of bioleaching have been used elsewhere. But the technology BioSigma has developed enables it to recover copper from sulfides two to three times more quickly than using other bioleaching systems, while between 30 percent and 50 percent more refined copper was recovered in tests, the company said.

For the first time, the use of certain bacteria allowed for successful copper processing from chalcopyrite, a mineral resistant to the sulphuric acid used in the standard leaching process, the company said.

“We have designed a process which uses bacteria, specific microorganisms, that are capable of acting with refractory minerals like chalcopyrite,” said BioSigma Chief Executive Pilar Parada.

BioSigma, which has over 80 patents from various countries, said the cost of the technology would be between 30 cents and 60 cents per tonne for a project processing 100,000 tonnes of ore daily. (Reporting by Fabian Cambero; Writing by Rosalba O‘Brien; Editing by Jonathan Oatis)

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