TECHNOLOGY

Baja Mining develops manganese recovery process for its Boleo copper/cobalt/zinc project

Baja Mining should now be able to benefit from the big manganese content at its complex Baja copper/zinc/cobalt project through the development of a new extraction process.

TOULOUSE - 

A significant advance in recovering copper deposit byproducts has been achieved at Baja Mining's Boleo project in Mexico. Staff at the University of British Columbia's Hydrometallurgy Research Laboratory have successfully demonstrated that manganese metal can be manufactured from Boleo manganese carbonate using conventional hydrometallurgical processing steps. A sample of manganese carbonate produced during the 2006 demonstration pilot plant at SGS Lakefield was used as feedstock for the tests, which were done under the supervision of Dr.Thomas Glück, Baja's Manager Process Technology and Dr. David Dreisinger, Baja's Vice President-Metallurgy.

The key features of the Boleo manganese metal process are:

■ Boleo manganese carbonate is leached to greater than 99% efficiency in the manganese leach solution (electrolyte from the manganese plating cell)

■ Minor impurities present in solution are removed using sulphide precipitation and clarification

■ The purified solution is electrolysed in a conventional manganese EW cell. A smooth grey deposit of manganese metal was plated over a six-hour period at a current efficiency of 65%. This represents typical commercial performance

■ The manganese metal is plated without the addition of selenium-a condition that ensures a higher quality product.

"Being able to produce manganese metal without adding selenium will differentiate Boleo manganese metal from the majority of the product available in the market," says Glück. "This is something our Korean partners are particularly interested in." Baja President and CEO John Greenslade said: The "result provides added confidence in our ability to produce manganese metal at Boleo once the copper, cobalt and zinc circuits are up and running and could add significantly to the economics of the project."

Boleo is the world's sixth largest manganese deposit. Current Boleo mining and processing plans would allow for the production of up to 100,000 t/y of manganese metal. Further work on plating of Boleo manganese is ongoing at UBC and with other development partners toward the goal of producing a fully integrated flowsheet for converting Boleo manganese carbonate to manganese metal in the most efficient way possible.

Baja has a 70% interest in the Boleo coppercobalt-zinc-manganese project located near Santa Rosalia, Baja California Sur, Mexico. A Korean syndicate holds the remaining 30%. Baja is the project operator.

The target date for commissioning Boleo is 2012. A 2007 definitive feasibility study projected an average annual production for the first four years of 56,000 t of copper cathode, 1,500 t of cobalt cathode and 20,000 t of zinc sulphate. The project has Proven and Probable reserves that support a
mine life of more than 25 years. Anticipated cash costs in the first five years are $0.27/lb of copper, net of byproduct credits for cobalt and zinc, and with no credit for manganese.

John Chadwick is editor/proprietor of International Mining Magazine - www.im-mining.com