The slow death of 6,800' high McDame Mountain in the heartland of the Stikine Mountains in British Columbia's remote northerly Cassiar District, is coming about because of the wealth it contains -- asbestos, sometimes called "White Gold".
The slow death of 6,800' high McDame Mountain in the heartland of the Stikine Mountains in British Columbia's remote northerly Cassiar District, is coming about because of the wealth it contains -- asbestos, sometimes called "White Gold". It is gradually being whittled away until it will become a mere stub -- only a level plateau will remain. But, as the operation continues, two more mountains are growing with soft lines, comparatively soft texture, which blend in so closely with the landscape you would think an artist had placed them there -- this is the result of the tailings - the short fibres of the asbestos which the company has considered unprofitable to handle because of the cost of transportation to the outside market. The mine is linked by an all weather gravel road running 86 miles southwest from Mile 649 on the Alaska Highway. Watson Lake, at Mile 636 on the Alaska Highway, is the nearest community; air service is provided by the Canadian Pacific Airline Company at the Watson Lake airport.
The existence of this deposit had been known for many years -- prospectors used to tell of mountain sheep bedding down in the matted fibre that accumulated from the weathering of the outcrop. It was not until the Alaska Highway and other ones in the area were built that development work became economic and possible. A mill was started about a decade ago and, since that time, the operation has expanded steadily to its present capacity of 2,000 tons of asbestos per day.
The orebody is located at an elevation of 6,200' on a spur off the west side of McDame Mountain (6,800' in elevation). The fibre occurs as innumerable veins or seams up to 3" in width in the serpentine rock.
Mining is a year-round operation. Following drilling, the ore is blasted out from 30 foot benches on the mountain, loaded with power shovels onto heavy duty trucks, then taken to the grizzly where it tumbles down to the primary crusher and screening plant; here, by rejecting 30% to 5% of the barren serpentine rock, a comparably larger amount of fibre can be transported to the mill by the same equipment. This plant is at the head of a three-mile long continuous-powered aerial tram, to the mill. The aerial tram's total length from the upper loading terminal at elevation 5,800' to the lower tramline station at elevation 3,525' is 14,600', in two sections. There are about 180 eighteen-cubic foot buckets in the line which carry an average of 3/4 ton net weight. At the mill, the tramline ore is dropped directly into a hopper where it is crushed and dried in rotary kilns -- the ore has a high water content, particularly at the beginning and end of the mining season when snow and rain are prevalent. After drying, it is delivered by conveyor to a large covered dry rock storage building and, as required, it is moved by conveyor belt to the head of the mill.
The actual process of separating the fibre from the rock is based on the fact that, as the fibre is crushed and handled, it gradually expands or fluffs up so that it becomes lighter than the rock from which it is being separated. The mill feed is passed over horizontally gyrating screens, during which time the fibre tends to float on the surface. Because of its lightness, it is possible to separate it or draw it off by means of air suction or aspiration -- a process very similar to the action of a vacuum cleaner. The rock is further crushed to free fibres not released in the first crushing stage. The separated fibre is then carried by air through ducts to cyclone collectors and then over a series of gyrating or rotary screens which clean and grade the fibre. Exhauster fans handle over 200,000 cubic feet of air per minute in this aspiration process.
After the fibre has been cleaned of all rock and dust and separated into grades of different lengths, it is collected into bins ready for bagging. It is drawn from these bins and compressed into bags containing 100 lbs. marked with the proper grade. These bags are stacked on pallets holding 20 bags or one ton, which are carried by fork lifts to a fibre storage building ready for shipment. A fleet of company-owned semi-trailer vans transport the fibre 350 miles to Whitehorse in the Yukon where it is transferred for shipment by rail to Skagway (Alaska), and by boat to Vancouver. The fibre is stored in large company warehouses in Vancouver, for shipment to many industries throughout the world.
The value of the fibre in one ton of raw ore is about $20.00. After this has been processed and ready for market, the price varies from about $140. per ton for short fibres, up to about $750. per ton for the longer or spinning grades of fibre. Hand picked crude fibre is priced up to $1,500. per ton and this is why it is sometimes called "white gold".
The spinning grades which contain the longer fibres are used to make yarns, textiles, electrical insulation, etc. The shorter fibres (the Asbestos cement grades) are used in asbestos cement, pressure pipes, sheeting, wall boarding and roofing materials used in the building trades. Brake lining, gasketing and heat resistant products also use considerable fibre in their manufacture. Cassiar asbestos due to its exceptional quality and length combined with a low magnetic iron content and freedom from talc and dust, make it a valuable commodity in the world markets. A good portion of the fibre is of the spinning grade and it is essential that all foreign material such as wood, paper, and wire be kept out of the ore during the mining and milling processes. A well equipped laboratory provides technical facilities to control the standards of the various grades of fibre. An addition to the laboratory was recently made to test asbestos cement products.
Transportation charges to the outside markets have always been one of the prohibitive factors of mining in this area. A new road is being built which will shorten the journey and the company may decide to process some of the ore now stored in the man-made mountains.