JM Asbestos heads underground — Noranda’s Magnola to produce magnesium from tailings

JM Asbestos, owner and operator of the Jeffrey asbestos mine in Quebec’s Eastern Townships, is winding down its open-pit operations and gearing up for underground production, to begin in the year 2000.

“There has been open-pit mining here since 1881, so it’s a big change for us,” says JM’s president, Bernard Coulombe. “But this move will secure our future for the next 25 years.”

Asbestos mineralization at Jeffrey occurs in the form of chrysotile — a thin, often-hollow, fibrous variety of serpentine — in a serpentinized peridotite orebody surrounded by slate.

Near the bottom of the 350-Metre-deep, 2-km-wide Jeffrey pit, workers are excavating a 1.7-km-long access ramp which, after a single switchback, will pass below the pit to reach the orebody at a depth of about 600 metres.

Developed reserves stand at 80 million tonnes with a 6.5% fibre recovery, whereas total proven reserves are estimated at 200 million tonnes with a similar recovery. (In the asbestos industry, `grade’ refers to fibre length and other physical properties.)

On a recent trip to the project, The Northern Miner learned that underground mining will be achieved by means of block-caving at a rate of about 15,000 tonnes per day. Ore will be hauled by train to an underground crusher and then hoisted to surface via a 650-Metre-deep shaft, now under construction.

The shaft that was used to pump water from the open pit will continue to be used for that purpose.

JM Asbestos is paying for the $125-Million underground development by reinvesting some of its profits and borrowing $40 million.

To ease the transition from open-pit to underground mining while, at the same time, sustaining production levels, JM has begun stockpiling ore. Coulombe says the firm does not want to be rushed in its underground development and thus suffer the kinds of technical problems that forced the closure of the Cassiar asbestos mine in British Columbia when it underwent similar development.

Ownership in JM Asbestos is split among management (55%), employees (30%) and the Quebec provincial employees’ pension fund (15%).

Some 700 people now work at the Jeffrey mine and processing facility.

Although underground work requires skills different from those of open-pit mining, JM has offered to retrain some of its younger workers.

Current production at Jeffrey stands at 210,000 tonnes of chrysotile annually, or about 40% of Canada’s annual production. The remaining 60% is produced by competitor LAB Chrysotile in Thetford Mines, Que. (T.N.M. Oct.

23/95).

At Jeffrey, chrysotile fibres are won from the ore through a fully automated process of crushing and drying. From the mine, ore is fed into a primary gyratory crusher, which has an hourly capacity of 2,500 tonnes, before being moved to secondary crushers. The crushed material is then screened and dried.

Final fibre separation and sorting are performed on-site in a 12-story mill, one of the largest and most modern facilities in the asbestos industry. Its top floor houses fans capable of drawing 140,000 cubic metres of air per minute through 100,000 fabric filter bags.

The asbestos count in the air breathed by mill workers is kept below the legal limit of 1 fibre per cubic cm. The air quality in the mill represents a major advance over conditions in the late 1940s and 1950s, when chrysotile processing occurred under atmospheric air pressure rather than the present-day low-pressure environments.

The final chrysotile product is divided into more than 100 different fibre grades, which are differentiated by properties such as length, strength, openness, filterability, bulk and absorption. The sorted fibres are then packaged in 50-kg bags and stored in a warehouse before being trucked to Montreal, where JM maintains a sales office.

Mill tailings are put on trains and unloaded into a nearby level tailings dump.

Worldwide, 80% of asbestos is used in cement, in which the fibre can make up 15-20% of such products as walls, pipes, sheets and tiles.

Asbestos has many qualities that make it a desirable building material. It is lightweight, flexible, incombustible, of high tensile strength and resistant to chemical attack.

Some 17% of asbestos, often of shorter-length grade, is used in friction products such as brakes and gaskets.

Despite the technological innovations in the asbestos industry since the 1950s, the industry continues to fight against the residual mistrust of its product. While it is proven that inhaling high concentrations of asbestos over many years can cause asbestosis, lung cancer and mesothelioma, the industry claims the modern asbestos worker and user are no longer exposed to the elevated levels seen in decades past.

Currently, eight European countries have some degree of ban on asbestos.

Particularly aggravating to Canada’s exporters is France’s ban on the sale and use of asbestos, which took effect Jan. 1. The prohibition, which represents a loss of an annual 28,000-Tonne market, is seen by the industry as more the result of hysteria and political expedience than of scientific research.

“When it comes to the hazards of asbestos, it’s a matter of dose,” says Jean-Franois Lavalle, JM’s senior vice-president. “Why ban something when you can control it?”

In response to the European bans, JM supports the Asbestos Institute — a Montreal-based, government-funded lobbying agency — in its ongoing efforts to promote the safe use of asbestos.

As a gesture to the French, intended to display the robust health of JM workers, the company sponsored several of its employees in April’s Paris marathon.

In other developments at Asbestos, a portion of the JM tailings dump has been sold for $1 to Magnola Metallurgy. The tailings will serve as feed for a planned $525-Million magnesium-processing facility to be situated adjacent to the dump.

Formed two years ago, Magnola Metallurgy is a 52%-owned subsidiary of Noranda Metallurgy, a fully owned subsidiary of Noranda (NOR-T). Owning a 16% interest each in Magnola are SNC-Lavalin, the Societ Generale de Financement du Quebec and a consortium of Japanese automotive parts manufacturers from the Aisin Group.

The facility, called the Magnola project (after magnesium-Noranda-Lavalin), will be the first of its kind to use technology developed by Noranda Metallurgy to produce magnesium commercially from serpentine tailings. The tailings typically contain about 24% magnesium and are in no short supply in the Eastern Townships. The project would create 400 jobs and add some much-Needed diversity to the local economy of Asbestos.

Magnola has already spent $36.5 million building a pilot magnesium-processing plant at Noranda’s zinc refinery in Valleyfield, Que. The pilot program should be completed by the end of 1997, and construction would then begin on the commercial plant, which is expected to yield 58,500 tonnes of magnesium per year.