May 12, 2016 / 6:42 PM / 2 years ago

Codelco eyes new technology to clean Chile's high arsenic levels

SANTIAGO, May 12 (Reuters) - Chile’s Codelco is considering building a $370 million plant that will use new technology to remove arsenic from copper concentrate, creating a cleaner and more saleable product for the world market, a company executive told Reuters on Thursday.

Autoclave technology, already used in the nickel and gold industry, is now being applied in Chile to copper for the first time by Codelco unit EcoMetales, its managing director Ivan Valenzuela said.

The EcoMetales autoclaves use oxygen at high pressure and temperatures to treat concentrate, increasing the proportion of copper and removing arsenic.

As the easier deposits in Chile, the world’s biggest copper producer, have become tapped out, miners are turning to rockier, dirtier ore to produce the base metal.

But Codelco needs to make its product acceptable to customers, especially in China, the largest importer of Chile’s output. Most smelters will not process concentrates with arsenic levels above 0.5 percent, for health and safety reasons.

It is also facing stricter environmental standards in Chile, where rules on arsenic emissions from smelters are being tightened.

Its newest mine, Ministro Hales, produces ores with high levels of arsenic and uses a roaster to reduce them. Plagued with technical issues at the roaster in its ramp-up in 2014-2015, Codelco was forced to cancel some sales and blend ‘dirty’ and clean concentrate.

Codelco’s multibillion-dollar project to take the century-old Chuquicamata mine underground, which is scheduled to be up and running in the mid-2020s, will also produce high-arsenic ore.

Codelco is eyeing a suite of solutions to tackle that, Valenzuela said, adding that autoclave technology was particularly attractive because the resulting output was ready for cathode production.

“This (plant) is a more than reasonable option,” said Valenzuela. Codelco will decide at the end of the year whether to go ahead with the plant, after an ongoing feasibility study ends.

The plant would be built close to the mining center of Calama in northern Chile, and would be able to process some 200,000 tonnes of concentrate annually, resulting in 60,000 tonnes of refined copper.

Chile produced 5.76 million tonnes of copper last year. Chuquicamata, Ministro Hales and nearby Radomiro Tomic produced a combined 862,600 tonnes.

EcoMetales already runs a plant near Calama that processes smelter residue dust to recover some 8,000 tonnes of copper annually for Codelco.

It is in talks with other companies interested in both technologies, Valenzuela said.

Reporting by Fabian Cambero, Writing by Rosalba O'Brien; Editing by Alan Crosby

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