Opemiska hoists last ore after operating 38 years

Opemiska, the mine that was the backbone of Minnova’s (TSE) operations for almost 40 years before being mined out this year, may live on as a milling facility for ore mined from other deposits in the Chapais and Chibougamau areas in Quebec.

Last ore from Opemiska was hoisted June 27, says Minnova President David Watkins, but the mill will stay in place on a standby basis “in the hope of opportunities in the area in the future.”

The tailings area for the mill is not filled to capacity and existing tailings do not pose any environmental problems because they are not acid generating. Watkins says Minnova plans to spend “several million dollars over the next few years” to continue exploration in the area.

Minnova’s most advanced nearby project is Lac Frotet which is undergoing detailed engineering studies and further diamond drilling. Current estimated reserves, to a cutoff depth of 200 metres, stand at 21.5 million tonnes grading 0.18% copper and 2.05 grams gold per tonne.

Opemiska, first discovered in 1926, went into production at the end of 1953 with about 550,000 tonnes of reserves grading 6% copper. Since then it has produced 500,000 kg copper (1.1 billion lb.), 24.6 tonnes gold (790,000 oz.) and 255 tonnes silver (8.2 million oz.) from about 29 million tonnes of ore.

The deposit was first under control of Prospectors Airways Ltd. In 1930 those assets were spun off as a separate company, Opemiska Copper Mines, with Falconbridge founder Thayer Lindsley as president.

In 1971, Opemiska and two other companies combined to form Corporation Falconbridge Copper which in 1987 changed its name to Minnova. The mine became known as Minnova’s Opemiska division.

Watkins says the mine was at its end about 18 months ago, but the company decided to continue operations on a break-even basis until mid-1991 so that the closing and relocation of staff could be done smoothly.

“We planned to run six months in a deficit, the next six months at break-even and the final six months at a profit to recoup the deficit of the first six months,” says Watkins.

The first two 6-month periods went as planned but in the final six months the mine did “three or four times better than expected,” he says, because of higher copper prices than anticipated.