Chile's state copper company Codelco is evaluating Teniente Converter (TC) technology to process the arsenic-rich copper ore at its Alejandro Hales project, the company's director of technological innovation and research Pedro Morales told BNamericas.

"We will concentrate the mineral and we are evaluating whether to process the concentrate by roasting or if we are going to send it to a Teniente Converter," said Morales.

Earlier in May, Codelco announced that it had dropped plans to build a plant to bio-leach copper concentrates with high impurities, designed to treat Alejandro Hales' (formerly Mansa Mina) ore, because it was not economically feasible.

The proposed plant was part of a JV between Codelco and Anglo-Australian BHP Billiton, called Alliance Copper, established to develop on an industrial scale BHP Billiton's BioCOP bioleach technology using installations at Codelco Norte.

Morales said there were already two Teniente Converters at Codelco Norte division, where Alejandro Hales is located, and the company is analyzing whether to use existing installations or build a new TC.

"The arsenic is released as gas, it is captured and then through a technology in development by Codelco it will be transformed into ferric arsenate, a stable composite," said Morales after giving a presentation at the II International Conference on Mining Innovation (Minin) in Santiago.

Morales said Codelco was putting the finishing touches on the solution to process Alejandro Hales ore and that the project should enter the basic engineering stage soon.

Alejandro Hales' environmental impact study (EIS), approved last year by Chilean authorities, outlines investment of US$900mn to build the open-pit mine operation.

If approved by Codelco's board, Alejandro Hales would mine 50,000t/d at an average grade of 1.18% copper to produce roughly 188,000t/y of copper, according to the EIS.

Codelco executive president José Pablo Arellano said this week that the project should go before the board of directors for approval in the next few months.

Alejandro Hales is 5km north of the town of Calama in Region II and 8km south of Codelco's northern division Codelco Norte.