Qubec: Casa Berardi Reawakening

The Casa Berardi gold mine is showing all the signs of heading back into production. The results of a revised feasibility study are expected in the last quarter of this year, but 100%-owner Aurizon Mines Ltd. is so confident that it has gone ahead with underground development.

The 14,000-hectare Casa Berardi property extends 37 km along the Casa Berardi Fault. The East mine opened in 1988 and the West mine in 1990 under owners TVX Gold (holder of Inco Ltd.’s gold assets) and Golden Knight Resources. The two ramp-access underground mines produced 690,000 oz of gold before they closed in 1997 due to depleted reserves. By then Inco had run out of interest in gold, and sold off the property, which was picked up by Aurizon, a Vancouver-based junior.

Aurizon has been remarkably successful in expanding the resources. “This is one of the three main exploration projects in the Abitibi, along with Doyon/LaRonde and Sigma/Lamaque,” says Aurizon’s general manager Michel Gilbert.

By early 2000, based on 80-m-spaced deep exploration drilling from surface, the West mine had reserves of 6.9 million tonnes at 6.7 g/t Au, for 1.5 million oz Au, mainly in two new zones (113 and 118) below and to the east of the old workings. The feasibility study that year recommended a capital expense of $121 million over a 30-month period, including sinking a 1,033-m vertical shaft from surface into these two zones and bumping up the existing mill to 2,800-tonnes/day capacity. Total cash costs were estimated at US$145/oz, over a mine life of 7.5 years and a payback period of 4.3 years. With the price of gold languishing at US$250/oz, the plans were shelved.

As the gold price bounced back, West mine exploration began again in 2002. An underground drill program was made possible by development work: the extension of the mine ramp from the 450-m to the 550-m level and driving a 660-m exploration drift, with a 145-m crosscut through zone 113 and the fault. Zone 113 drilling is now complete on 25-m centres between 450-m and 700-m depth, moving previous resources defined by the surface program into the reserves category.

Surface exploration has shifted to the East mine, where the company expects to drill 40,000 m in 2004. Two new zones (140 and 157) have already been discovered.

In March this year the company hired Met-Chem Canada Inc. to update the feasibility study. The intentions were to extend the mine life to 10 years, reduce the cost to $100 million and drop the pre-production period to 20 months. A 2,200-tonnes/day throughput will put less pressure on the mill. The payback should be in only three years. Gilbert hopes the mine will be in production by the end of 2006 or early 2007. The study should be complete in October.

The definition drill results have been so encouraging that Aurizon has jumped the gun. The ramp to zone 113 is already complete, and the shaft has been started. Instead of conventional methods, the shaft will be constructed by driving two Alimak raises simultaneously, one from 550 m to 280 m, and the other from 280 m to surface. This should reduce the construction period considerably. Talpa-Thyssen was hired to construct the 31-m-deep collar. The soil and overburden are being frozen down to bedrock, rather than using a conventional cemented slurry wall, again to reduce time and cost.

To prepare for its transformation into a mine operator, Aurizon began last year to build a technical team, attracting key staff from large corporations. The 32-person team has an average of 25 years of experience.

“This has been step-by-step growth,” says Gilbert.