Startup troubles reported at Cominco smelter, Red Dog

Startup difficulties have plagued the new lead smelter owned by Cominco (TSE) in Trail, B.C., where the company has been experiencing problems since mid-December. The primary operating problem is associated with the reduction section of the metallurgical process. Reduction involves the injection of natural gas with oxygen into a molten slag bath, and the resulting reaction causes the lead to be reduced from the slag. Although the plant can operate successfully at low rates of feed, the reduction reaction is incomplete at higher rates.

Cominco, working on a solution to the problem, is operating the old smelter at 50% of capacity. The company also cited a number of boiler leaks and minor mechanical problems as further reasons for low production.

Production from both the old and the new smelters is about two-thirds that of last year.

Meanwhile, at Cominco’s new Red Dog lead-zinc mining and milling complex in Alaska, startup problems are also being encountered.

The concentrator is operating at 50% of capacity as one of the autogenous grinding units is down for realignment. “Since the first concentrates were produced last November, operations have been intermittent as various plant deficiencies were corrected and on-the-job training of the local labor force began,” said a spokesman.

He said the grinding circuit and flotation circuit are operating well, but the filtering section has been a problem.

“Lead metallurgy is proving somewhat difficult because of oxidized ore in the upper benches of the pit,” he said. However, this is considered to be only short-term problem, and no difficulties are expected in providing feed for the concentrator.

Zinc metallurgy is reported to be good, according to the company, and planned recoveries and concentrator grades are being achieved. Other reports suggested that copper in the ore may also be interfering with the recovery process.

The open pit mine is said to be operating well with the normal delays due to weather — not unusual to northern operations.

Transportation of concentrates from mine site to port site has been disrupted at times because severe winter conditions. “The startup of a large mining operation, 200 km north of the Arctic Circle, in midwinter is a challenge,” the company admitted.

In the early 1980s, Cominco successfully overcame startup challenges and began producing lead- zinc concentrate from its Polaris mine, 100 km from the magnetic North Pole. That operation became the world’s most northerly metal mine, on Little Cornwallis Island, N.W.T.

The market has taken news of startup difficulties at Trail and Red Dog in stride with Cominco’s shares trading recently at $23.50, down 25cents from a high of $23.75 last week.