THE SEARCH FOR SILVER

As a precious metal, silver has suffered a sad fate: Not only has it always stood in the shadow of its renowned cousin, gold, but now it garners less and less attention as the platinum group metals grab more of the public spotlight. Of course, to the mining companies that produce the metal in Canada, it doesn’t really matter. Silver still makes them money and that’s what really counts. In terms of world mine output, Canada is a top gun among producer nations. Mexico stood first in 1987 with an output of 2,250 tonnes of refined silver. Next came Peru with 1,865 tonnes and then the United States third with 1,250 tonnes and, fourth, Canada with 1,186 tonnes. Between 70% and 80% of domestic production is mined as a by-product of base and precious metal mines. For example, Canada’s largest silver producer (at an annual 310 tonnes) is Falconbridge Ltd., which gets the lion’s share of its silver output from the Kidd Creek base metal mine in Timmins, Ont. Brunswick Mining and Smelting is a close second at roughly 250 tonnes per annum.

The sole “pure” silver producer in Canada is Agnico-Eagle Mines. (It should be noted that Equity Silver Mines, despite its name, is a silver/copper/gold producer. Its silver production reaches 170 tonnes a year.) One other mine, the Hellens Eplett mine, owned by Silverside Resources and International Platinum, is attempting to become the country’s second “pure” silver producer. It’s rather fitting that both Agnico and Silverside/International Platinum are working the famed silverfields around Cobalt, Ont.

In one corporate guise or another, Agnico-Eagle has been blasting silver out of the Cobalt ground for decades. Under the direction of President Paul Penna and Cobalt veterans such as Gordon Kirk (an Agnico director and mining consultant) and Chief Geologist Brian Thorniley, Agnico-Eagle’s silver division is operating three mines _ Beaver-Temiskaming, Castle and Langis.

All the mining is done by shrinkage stoping with conventional jack legs and stopers. Track equipment, mainly because of the narrow 5-ft widths, is used in mucking and hauling. The veins can be as long 200 ft and as high as 100 ft, says Mine Manager John Young. Except for the fact that the veins are nearly vertical, the geology of the Cobalt silver mines tends to be erratic, with the veins pinching and swelling.

“Sometimes we’ll even just follow a crack in the rock (after mining along a vein) to see where it goes,” Young says. “But one vein will lead us to another.” Because of the nature of the geology, building a reserve is impossible. “The only reserve is broken ore,” he notes. The vein widths range from less than 1/2 inch to as much as 5 inches of high-grade silver laced with calcite and cobalt.

Ore from the three mines is trucked to Agnico-Eagle’s new mill, where it is crushed, ground in a ball mill and concentrated by gravity and flotation. The company’s own refinery turns out silver bullion. The mill is operating at a rate of 270 tons per day and Agnico is aiming to produce 1 million oz of silver this year.

Agnico’s commitment to Cobalt and the surrounding area continues to pay off, not only in terms of current production, but also in exploration. Last year, construction began on a new, 1,200-ft shaft less than half a mile from the Langis mine. Earlier diamond drilling had revealed several vein intersections along a 3,000-ft strike length to a depth of 800 ft. Young says the shaft should be completed by mid-September, and production should follow roughly a year later. Exploration by means of ramps is also being conducted on two other properties near Cobalt.

While Agnico-Eagle profitably plugs away, Silverside Resources and International Platinum inch closer to what they believe will be a production decision on their Cobalt silver property in Lorraine Twp. Between mid-February and July, the mill reached a 50- to 55-ton-per-day capacity with recoveries up to 93%. The mill has since been shut down pending receipt of an export licence to ship the mill’s concentrates out of the country.

According to James Trusler, International Platinum’s vice-president of exploration, the concentrates contain cobalt and arsenic and this has made smelting in Canada difficult. So the mine’s planners are considering shipping the flotation circuit concentrates to processing plants in Belgium, France, or Sweden. The gravity concentrates may be shipped to Finland. The Agnico-Eagle mill has processed some of the gravity-circuit material.

Underground, the operating company, Hellens Eplett Mining Inc., has embarked on a $600,000 diamond drilling program to block out at least two years of reserves. This reserve figure and a projected 100- to 120-ton-per-day operating capacity would form the basis of a mining decision, Trusler told

The Northern Miner Magazine<<.

During test mining, seven stopes were worked using a modified shrinkage stoping method called rill mining. This is simply the building up of a pile of ore in the stope as cuts are taken, but mining upwards in apex fashion (like a pyramid). Miners can then slush out to drawpoints without the need for excessive timbering. While stope sizes vary, mining widths are a minimum 5 ft. Some stopes that have clusters of veins or veinlets can be mined to a 20- or 30-ft width.

“We’re in a learning mode right now,” Trusler said of the geology and mining of the deposit. “The No. 4 vein we’ve developed along 450 ft. We have two levels and raised above that second level. The veins seem to change characteristics. The silver may be in a vein at one point and then we come across another type of mineralization in that vein. But then the silver carries in a parralel vein. It’s a matter of getting a handle on it.”

Calculated millhead grades so far have ranged between 15 oz and 60 oz per ton. The average has been 25 oz, Trusler said. Access to the underground workings is by way of a 2,800-ft ramp that goes to a vertical depth of 400 ft. and a small, two-compartment shaft to the west of the workings.