COMMENTARY — Cooling the air at Coleman

If you can’t take the heat, get out of the mine. Or drive a ventilation shaft.

Which is exactly what Coleman miners did in near-record time, without incident and under difficult conditions.

“It was kinda hot down there so we wanted to get the job done as quick as possible and get the blazes out of there,” Coleman miner Russell Marlow said. “Getting the job done” meant driving 5,500 ft. of McCreedy East access drift through solid rock from the Coleman mine to the McCreedy East No. 1 shaft. Coleman miners began driving the drift in August, 1992, and Coleman miners broke through in the first weekend in June of this year.

“It was done in excellent time,” General Foreman John Draper said. “It was the priority drift at the mine and it had to be driven quickly to provide needed ventilation to enhance production at Coleman, as well as provide access to the McCreedy East orebody.

“Our people here knew that it was critical that this drift go on, and everybody worked together to get the job done. The men on the four crews were instrumental in achieving excellent development rates over a long period of time on one single heading, but it was everybody working as a team that made it possible.”

So important was the drift that development rock took priority over production ore. This required fine-tuned scheduling and careful co-ordination to avoid affecting production rates.

Four crews of three men took turns doing the excavation, with crews working around the clock, seven days a week. “It was,” John said, “something of a milestone.”

Conditions were uncomfortably warm, with heat created by five booster fans which were required for ventilation. Every other attempt was made to reduce heat. Although it meant some restrictions, electric load-haul-dump machines were used, as they operate at cooler temperatures than do diesel machines. Before the breakthrough to the McCreedy drift, miners worked in temperatures of about 86F. In just a few minutes, the natural flow of air created by the breakthrough dropped the temperature by almost 20.

Advance rates averaged more than 10.4 ft. per day over the duration of the project and drift size was 20 ft. wide by 13 ft. high for the first 2,000 ft., and increased to 20 ft. by 16 ft. for the remainder of the drive. Crews used a 2-pass bolting system to increase advance rates.

— From a recent issue of Inco’s “Triangle” publication.