Rock mechanics integral part of day-to-day mine operation

“They form an integral part of our ground support system,” S.M. Reid, mine manager of the Placer Dome (TSE) gold-producing property, said.

The company has installed a mine-wide computerized monitoring (micro-seismic) system to check for underground movement and/or possible rock burst activity. Both management and the workers “are constantly aware of what is happening in the mine all the time,” said Reid.

The monitoring system is able to tell when there is activity, but it has not yet been advanced to the point where it can predict when or if a burst is imminent, Reid said.

Ted Nelson, chief engineer of the Macassa mine of LAC Minerals (TSE) at Kirkland Lake, Ont., said his mine employs a similar computerized system which interprets seismic information from about 20 geophones (electronic listening devices) strategically placed underground. Macassa is being mined to a depth of 7,000 ft.

Advising the Macassa management on ground control matters is a southern Ontario consulting firm with computer software able to model an opening or stope for use in predicting stress or rock control troubles in that area of the mine. Nelson said the firm visits the mine annually for an audit.

In northwestern Quebec, at the Camflo gold mine of American Barrick Resources (TSE), careful attention is given to rock mechanics, mine manager Richard Mailloux said.

While there is no computerized system in operation, Camflo supervisors base their decisions on their own experience with the ground. Mailloux said that should problems in interpretation develop, an outside consultant is hired to provide expert advice.

At the Lupin gold mine of Echo Bay Mines (TSE) in the Northwest Territories, Bill Burton, chief engineer, described the property as having “highly competent rock.” Because of the hard rock and the relatively shallow depth of the mine (the most active level is about 2,100 ft deep), no monitoring system has been installed, he explained.

Despite the absence of ground control problems to date, Burton said Lupin management does anticipate having to introduce a monitoring system sometime in the future.

A rock mechanics consultant is hired to undertake an annual underground audit at Lupin, he said.

At Inco Gold’s Golden Pond gold mine in Quebec’s Casa Berardi area, the operation is new and shallow enough that no electronic monitoring system has been installed. The mine went into production last year.

Management is, of course, able to call on the expertise of its parent, nickel giant Inco Ltd. (TSE). Mine manager Aurelio Petracchi said a team of Inco personnel from Sudbury recently spent three days at the mine checking the soundness of the rock.

Petracchi said his staff at the mine includes a geological engineer who was sent to Sudbury for training specifically in rock mechanics.

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