Technological improvements bolster Campbell mine

In an age when precious metal producers are struggling with the bottom line, the Campbell mine of Placer Dome (TSE), in the heart of the Red Lake gold camp, is ploughing through tough times with an enviable orebody and record-breaking production.

Last year it singlehandedly salvaged Placer’s North American profit picture, contributing US$45.1 million to corporate coffers. However, optimizing efficiency has brought its fair share of personnel problems to the “Campbell family mine” and the recent termination of 99 workers from the flagship operation has left the work force concerned about the future. In spite of employee downsizing, production at the Balmertown facility has never looked brighter. According to mine manager Tim Mann, the 1992 production target of 275,000 oz. represents about a 5% increase over the 1991 delivery of 260,582 oz.

Mann is confident that production targets will be met in spite of the 20% manpower reduction and cites recent technological improvements to the mill and increased tonnage throughput as reason for his optimism. The main technological improvement is the $26-million pressure oxidation circuit, or autoclave, commissioned last July. It is designed to efficiently extract gold from Campbell’s sulphide-associated refractory ore and will contribute an additional 2,500 oz. to production figures.

In May of 1990, a new enhanced capacity, carbon-in-pulp circuit was also commissioned and according to plant superintendent John Frostiak, that upgrade significantly reduced solution losses.

“The only remaining bottleneck (to the mill) was the flotation circuit,” said Frostiak. That problem was dealt with last December, and mill efficiency was further improved when the old Denver flotation circuit was replaced by a column flotation circuit.

This year, Placer recorded a first-quarter recovery rate at an incredible 98.6%, up from 94.2% for the same period in 1991. Frostiak says the 98.6% rate includes gold taken from old decommissioned equipment. However, he is also confident that the average recovery target for 1992 of 96% should be achieved.

With numerous high-grade headings and a trend towards more mechanized mining methods, Campbell has relatively few problems in achieving increased underground tonnage. However, getting that muck to surface and efficiently processing it has meant a considerable investment in technology. In order to facilitate enhanced hoisting capacity, skip payload was recently upgraded from 5.5 tons to 6.7 tons and electrical modifications have increased rope speed to 1720 ft. per minute from 1640.

Recent enhancement to the shaft through changes to the skip dump facilities and some stiffening of the headframe has boosted skipping capacity to a maximum of 1,840 tons per day.

Increased mill tonnage was facilitated in 1987 with the construction of an extra capacity grinding circuit. According to Frostiak, that extra capacity, coupled with subsequent modifications, has boosted mill throughput to 1,430 tons per day.

The plant superintendent is also confident that 1992 targets of 275,000 oz. from 483,000 tons, grading an average of 0.59 oz. gold per ton will be achieved.

The Campbell orebody is an extremely high-grade deposit. In fact, Campbell operates with head grades hovering around 0.6 oz., one of the highest-grade precious metal operations in North America.

For 1989-90, the mine released figures inferring 6.2 million tons grading 0.63 oz. However, in March of 1991, adopting a more conservative approach to ore reserve calculations, the published figures stated were 5.4 million tons with an average grade of 0.56 oz.

A good indication of the extremely high-grade nature of the Campbell deposit is Mann’s recently declared “break-even cutoff grade of 0.265 oz.” He also postulates that with a cutoff grade of 0.5 oz., “the ore reserves would have been 2.6 million tons grading 0.78 oz.”

Mann says an aggressive diamond drilling program is effectively replacing the mine’s ore reserves. “In 1991, while the mine and mill chewed up 430,000 tons of ore reserves, exploration and development put back 533,000 tons . . . . For 1992, our budget calls for 122,558 ft. of diamond drilling, 30,000 ft. of which will be used to test the potential below 27 level.”

Mann has been mine manager since May, 1990, having previously been mine manager at Placer Dome’s Detour Lake gold mine in northeastern Ontario where he initiated the transition from open pit to underground producer. Mann arrived at Campbell to find a work force of 502 employees. Almost immediately he began downsizing the operation. Several senior staff positions were eliminated in 1991 and, in April of this year, a further 99 employees, about 20% of the total work force, were terminated.

That move coupled with enhanced technology, increased throughput and cutting back on subsidies like employee room and board, and local bus service, Mann has estimated reductions to production costs of 19.2%.

From a currently budgeted cost per ton of $117.22, Campbell should start processing ore, commencing in the third quarter of this year, for $98.36 per ton.

The United Steelworkers of America union is currently mounting an aggressive campaign to unionize the work force.

With the aftermath of personnel problems still being felt in the Red Lake district, it is evident that the local perception of Campbell as a “family mine” has been tarnished.

In spite of current morale problems, Campbell has remained a profitable, efficient and well-endowed gold producer. “By continuing to explore news ways of mining our deposit and extending our mine, we will keep Campbell viable well into the 21st century,” said Mann recently.

A somewhat more candid yet similar scenario was recently offered by the Ontario government’s Red Lake resident geologist, Brian Atkinson. “Campbell has been mining for over 40 years and its likely it will outlast most of us.”