Taseko considers refinery for Gibraltar

Preliminary results from pilot-plant metallurgical tests have prompted Taseko Mines (TKO-V) to proceed with a feasibility study for a copper refinery that could revive the dormant Gibraltar copper mine, near Williams Lake, B.C.

Taseko acquired the 35,000-tonne-per-day mine-and-mill facility in 1999, with a view to examining its potential for producing copper cathode from concentrates using an innovative hydrometallurgical process developed by Cominco Engineering Services (CESL), a division of Cominco (CLT-T). Taseko and CESL have since signed a joint agreement to evaluate the feasibility of the refinery proposal. Costs are being shared equally by the partners, with more than $1.4 million having been spent to date.

A scoping study by the partners in mid-2000 showed that the cash cost of copper produced at the mine could be slashed by as much as 20 per lb., mostly by eliminating shipping and smelting/refining costs. The study was subsequently reviewed by Bateman Hatch Engineering, which concluded that the process is technically sound and that the projected costs are reasonable. The independent engineering firm was previously involved with the development, design and construction of the Mt. Gordon copper project in Australia, which began production more than two years ago. This operation, which integrates low-pressure oxidation to treat run-of-mine ore and produce cathode copper, is viewed as similar, in many respects, to the flow sheet proposed for the copper refinery at Gibraltar.

Taseko recently trucked 900 tonnes from Gibraltar to CESL’s demonstration plant near Vancouver, where it was processed into 7 tonnes of concentrate grading 24% copper for testing. The company noted that testwork to date “has confirmed operating parameters, such as copper recoveries and the autoclave retention time, used in the scoping study.”

Bateman Hatch will begin a feasibility study shortly, once all testwork is completed. Taseko and CESL expect the study to be completed by late June of this year. In the meantime, environmental and permitting work will continue, along with drilling to test exploration targets outlined during last year’s geophysical programs.

Gibraltar operated for 27 years, until 1998, when it was closed by then-owner Boliden Westmin because of low copper prices. Sulphide resources, using a 0.2% copper cutoff grade, stand at 745 million tonnes, containing about 4.7 billion lbs. copper. This includes measured and indicated resources of 149 million tonnes grading 0.31% copper and 0.01% molybdenum in the 12-year mine plan, plus additional measured and indicated resources of 596 million tonnes grading 0.28% copper and 0.01% moly. The project also has in-pit, oxide resources suitable for processing in the existing solvent extraction-electrowinning plant.

If all goes as planned, the revived Gibraltar mine would operate for 15 years and create 280 full-time jobs.