GUEST COLUMN Unique solutions to problems of arctic mining

Cominco began its high Arctic development with the Black Angel silver-lead-zinc mine in Greenland in 1973. In 1982, it opened the Polaris lead-zinc mine in the Arctic Islands. And in late 1989, tune-up of the Red Dog silver-lead-zinc mine in Alaska began.

The challenges of developing an Arctic mine are immense: adverse climate, isolation, difficult access and a restricted shipping season.

The Black Angel mine, halfway up the west coast of Greenland, at latitude 71N, started up in 1973 at a rate of 725,000 tons per year. It finally shut down in July, 1990, after processing 12.5 million tons of ore in 17 years, double the original reserve of six million tons.

The ground at Black Angel is permanently frozen, down to 1,600 ft. in some places, and rock temperatures go down to about -12C. The plant site is a small, 30-acre area across the fjord from Black Angel cliff.

It was decided that the best method of access to the mine, 2,000 ft. up the 70 degree cliff, and almost a mile across the fjord from the plant site, was by cable car. Initially, a small secondhand unit was installed to service the mine for the development program. To build this, Swiss mountaineers were flown to the plateau by helicopter, climbed down to the portal site, and established the first entry suspended on ropes. This allowed excavation of the portals for the cable car, and the main haulage level of the mine.

Polaris, the most northerly metal mine in the world, is on Little Cornwallis Island, at latitude 76, 900 miles from the North Pole.

The deposit is much larger than Black Angel, with higher grade, and should be operating well into the next century. The Polaris mine reached commercial production in March, 1982, just 28 months after the “go ahead” decision by Cominco’s board and has operated by 25% above design rates since 1984. To the end of 1990, Polaris had processed about eight million tons, and the ore reserve at the end of 1990 was about 14 million tons.

The permafrost at Polaris is a definite plus, as, without the cementing effect of the ice, the ground could be quite unstable. It was necessary to install a refrigeration plant to cool the mine ventilation air during the warmer summer months.

The key to the Polaris project is the process-power facility. This unit contains the heart of the surface operation – the power plant, concentrator, shops, warehouse, changehouse, operations offices, labs and fuel oil storage.

This facility was constructed on a 100×400-ft. barge, on the St. Lawrence River in eastern Canada. The process of barge and plant construction took 15 months, from March, 1980, to June, 1981. The 3,000-mile voyage to Little Cornwallis Island took 20 days.

Red Dog, is one of the world’s great mineral deposits, with a unique combination of large size, high grade and low strip ratio. The mineral reserve is estimated to be 85 million tons, at a grade of 22% combined lead-zinc. Based on the current production forecast, this will give a mine life of almost 50 years.

The production plan is based on mining at a rate of 2.1 million tons per year to produce 720,000 tons of concentrates. At full production, Red Dog will be the largest zinc mine in the western world, and will supply about 7% of world zinc requirements.

The Red Dog mineral deposit is about 500 air miles from Anchorage, Alaska.

The Red Dog Creek flows through the mineral deposit. Heavy metal contamination in the creek has eliminated all fish in the vicinity of the deposit. This contamination is caused by rain and snowmelt leaching the heavy metals from the mineral zone, which comes right to surface in many places. Now that mining has commenced, and over the years, this surface mantle is being removed. That should improve the water quality in Red Dog Creek.

Red Dog, like Black Angel and Polaris, is completely isolated, so all infrastructure has had to be supplied.

For Red Dog, a total of nine modules, varying in weight from 800 to almost 2,000 tons, make up the process and power facilities. The modules were built in the Philippines, then transported by ship, barge and trailer to the mine site. The erection started in the spring of 1988. All modules were at the mine site by the end of September, 1989, and tune-up of the mill started in November.