Shaft-deepening seen as renewed commitment — Barrick digging

Toronto listed American Barrick has demonstrated a renewed commitment to its Holt-McDermott mine, 50 km north of here, by announcing an $8.7-million shaft-deepening project.

The bullish news also sends a clear and much-needed signal of optimism to the local economy and the gold-mining industry.

“We are encouraged by higher grades at depth and certainly pleased with the positive indications of an extended mine life,” Holt-McDermott Mine Manager John Haflidson told The Northern Miner.

Beginning in July, the shaft will be deepened by another 300 metres. The decision is based on recent results of a successful underground diamond drill program which outlined 750,000 tons of drill-indicated reserves grading 0.20 oz. gold per ton.

The new reserves, in the “south area of ore zones” have been delineated 260 metres along strike and vertically between the 800-metre and 650-metre horizons. An additional $250,000 drill budget has been allocated for the remainder of the year.

The new reserves are expected to extend the mine life by two to three years, quite possibly longer.

Besides deepening the shaft, the $8.7 million will go toward excavating a loading and a spill pocket, lateral development on two and possibly three levels, driving ore and waste pass raises, installing a crusher station, additional diamond drilling and miscellaneous pre-production work. A used 36×48-inch jaw crusher was acquired from the Camflo mine, a sister operation in Quebec that was recently closed. Production from the deeper zones is scheduled to come on-stream in 1995.

Actual sinking will be conducted by in-house personnel, which is nothing new to the innovative Holt-McDermott miners. The main shaft, completed to the 420-metre horizon in 1987 by contractors, was deepened in 1991 to the 650-metre elevation (the current shaft bottom).

A crew of 20 will consist of 16 shaftmen, three hoistmen and one mechanic. They will sink five days per week, three shifts per day.

With a core of sinkers assimilated into the workforce after the previous deepening, Haflidson expects only about 12 new hires from a talented pool of local miners. An existing 5-ft.-diameter sinking hoist will be used for conventional sinking by means of pluggers, a Cryderman mucker and a 5-ton sinking bucket. A new 118-inch-diameter, non-rotating, sinking rope was recently bought for the project.

The rectangular, 4-compartment, timbered shaft has an excavation cross-section of 10×28 ft. and consists of a skip, skip-cage and manway-service compartments. A new shaft bulkhead, in the final stages of design, will be at the 615-metre elevation, 60 metres above the existing loading pocket. Shaft waste will enter a finger from the dump door, be stored above the existing 590-metre loading pocket and then hoisted to surface as required via the main hoist.

Based on diamond drilling experience, Haflidson does not expect any water problems or deterioration of ground at depth. “Ground conditions at the mine are good,” he confirmed.

Following a short development and construction period, the Holt-McDermott mine and 1,500-ton-per-day carbon-in-pulp mill went into commercial production in 1988. Despite slumping gold prices and average millhead grades ranging from 0.10 to 0.14 oz. gold per ton since inception, the mine has stayed alive.

— Bill Glover is a mining engineer in Kirkland Lake, Ont.