Winston Lake zinc mine a boon for North Shore

Ontario’s first base metal mine to open in eight years, the Winston Lake zinc mine 23 km northwest of here, was hailed as a boon for communities along the north shore of Lake Superior during opening ceremonies at the mine site.

About 200 people turned out to see the ribbon-cutting ceremony. They were welcomed by Minnova (TSE) President Ian Bayer who recounted the 10-year story of the $73-million mine’s discovery and development. Also on hand were mine manager Tom Dickson, Cochrane North MP Keith Penner, Ontario Mines Minister Sean Conway and Minnova Chairman Keith Hendrick.

Ownership of the mine is being contested in the Ontario Supreme Court by Zenmac Zinc (ASE). Vice-president John Carrington said a representative of Zenmac was invited to the opening but did not attend. However, shortly after the opening ceremonies began, a small, single-engine airplane appeared in the cloudless sky over the site carrying a streamer that read: “Zenmac Zinc welcomes you to its Winston Lake project.” The plane circled the site for two hours.

Minnova is 50.2% owned by Kerr Addison Mines (TSE) which in turn is 50.1% owned by Noranda (TSE).

Both Conway and Penner, as well as company officials, emphasized the importance of the mine to the local economy.

“This mine is a boost to our communities,” said Penner. “We hope your stay here is as long as it can possibly be.”

The last base metal mine to open in Ontario was the Lyon Lake division of Mattabi Mines’, another Noranda subsidiary, at Sturgeon Lake. Prior to that it was another eight years since a base metal mine opened in the province and that was Mattabi’s first mine at Ignace, also in the Sturgeon Lake area. Only the Lyon Lake mine is now operating, producing zinc, copper, lead and silver. Inco also opened a nickel-copper mine in 1972 at Shebandowan.

The Winston Lake mine is not a large one compared to other base metal mines. It is designed to produce about 1,000 tonnes of ore per day. However, with reserves of 3.1 million tonnes grading 15.6% zinc and 1.0% copper, it should prove to be a productive mine. Mining costs are estimated at about $40 per tonne of concentrate.

Mining is currently being carried out on a high grade zone. Mill head grades are running at 20% zinc, so although the mill is not putting through its full 1,000-tonne capacity each day, it is shipping its targeted daily output of concentrate — 30 tonnes of copper concentrate, which contains gold and silver values, and 350 tonnes of zinc concentrate. The mill is designed to handle 1,000 tonnes per day averaging 0.6% copper and 16% zinc.

Metallurgical recoveries are expected to be about 70% for copper and 93% for zinc. The concentrate grades are expected to average about 23% copper and 54% zinc. The concentrates are shipped by CP Rail with copper going to Noranda’s Horne smelter for refining at Noranda, Que., and zinc going to another Noranda subsidiary for refining, Canadian Electrolytic Zinc, at Valleyfield, Que.

Virtually all of the mill equipment came from the company’s Sturgeon Lake property. The only new equipment 26 flotation cells and two automatic pressure filters.

Construction of the mine began in the fall of 1985 although the 741-m exploration shaft, which is now used for production, was collared in February, 1984. Development ore was hoisted to surface throughout 1987 and the first concentrate was produced in January, 1988.

The company says development is complete on the 615-m level, 80% complete on the 585-m level and 50% complete on the 565-m level.

The orebody, the top of which is 350 m below surface, is 2-15 m thick and dips at 50degrees. It will be mined primarily using a modified long- hole stoping method in which waste is introduced as fill immediately after mining. Two long-hole stopes are now producing and three others are being developed. Mechanized cut and fill, using mill tailings and cement as fill, will also be used as a supplementary mining method.

Minnova, then known as Corporation Falconbridge Copper, first staked ground in the area in 1979. The Zenmac claims were optioned in July, 1980. The terms of the option agreement are now the subject of a legal dispute.

Drilling was first conducted in 1981 with the fourth hole, drilled in July of that year, considered the discovery hole.

The project received the go ahead to be put into production in 1985, but a collapse in zinc prices caused that decision to be reversed. A federal government tax incentive for mineral exploration known as flow- through financing, permitted the sinking of the exploration shaft to 491 m during 1984 and 1985. In 1986, with metal prices improving, the decision to go ahead with the project was reinstated.

That decade-long history of the Winston Lake mine illustrates what Conway called one of the project’s “most impressive features; persistence and patience.”