TORONTO (miningweekly.com) – An updated mine plan for base metals miner Taseko Mines’ 75%-owned Gibraltar openpit copper/molybdenum mine, in south-central British Columbia, has improved the operation’s financial metrics, lifted reserves and extended the mine life.

The latest mine plan, the result of a detailed, six-month engineering study forming the basis of an updated National Instrument 43-101-compliant reserve, featured a 50% decrease in the strip ratio.

The study reduced the average strip ratio to 1.9:1 from 4.3:1, which would lower mining costs by reducing the volume of waste mined.

"Every point of strip ratio is equal to about 31-million tonnes of waste that does not need to be mined annually and, at $1.85/t mined, amounts to roughly $57-million of annual savings," Taseko president and CEO Russell Hallbauer advised.

During a March 26 telephone call with analysts, he noted that the previous mine plan, with its higher strip ratio, bottlenecked mining operations by limiting the release of ore and by maintaining a tight operating area in the mining zone.

As at December 31, Gibraltar had total proven and probable reserves over five openpits of 749-million tonnes, grading 0.256% copper and 0.008% molybdenum, or 0.272% copper equivalent. These reserves were contained within measured and indicated resources of 1.09-billion tonnes, averaging 0.254% copper and 0.008% molybdenum. These figures reflected a reduced cutoff grade of 0.15%, down from 0.2%, which offset the reduced strip ratio.

Under the new mine plan, Gibraltar, currently Canada’s second biggest opencast mine, would produce 3.3-billion pounds of red metal and 62-million pounds of molybdenum. The operation’s average yearly output would be about 138-million copper and 2.6-million pounds of molybdenum, at a milling rate of 85 000 t/d. The resources would support 24 further years of operation.