Increased uses for graphite

It is not a new industrial mineral by any means, and the market is relatively small. So why does it seem graphite, a naturally occurring crystalline form of carbon, is drawing more interest these days than might normally be expected?

And why is one type of natural graphite — flake — growing in preference to other forms?

Technology is more sophisticated these days and manufacturers are looking for better products, Michel Boucher of Energy, Mines and Resources Canada in Ottawa, said in response to the first question.

“Graphite is heat-resistant and anti-corrosive,” he said, and in the refractory business these two properties are in demand. The mineral, which melts at over 3600 C, is useful for making furnace bricks, and also, because it conducts heat well, in the manufacture of crucibles.

Nothing is “simply stated” about graphite. While a market is developing for natural graphite, the mineral has found acceptance in the industrial world in an artificial form, as a synthetic product made from petroleum coke and other petrochemical byproducts. Synthetic graphite, however, is expensive to manufacture and is usually applied only where high purity and an extremely high carbon content are required (in the making of an electrode, for example). Global output

Annual world production of natural graphite is about 600,000 tonnes, according to several sources. Groupe Conseil Roche Ltd., in a study conducted for Quebec-based junior Mazarin Inc. (TSE), reports there are 15 producer nations of natural graphite, with seven of those countries supplying more than 80% of the market. The main producers are China, Brazil, Norway, Madagascar, West Germany, Mexico and Sri Lanka.

Principal users of natural graphite are industrialized nations which account for 200,000-220,000 tonnes annually. (Global consumption numbers are difficult to calculate; some of the supplier nations — China in particular — make use of their own graphite and figures are unreliable as to how much the Soviet Union imports.)

A list of the mineral’s applications includes in batteries, brake linings, foundries, lubricants, pencils, refractories, rubber and steelmaking.

A spokesman for steelmaker Dofasco Inc. of Hamilton, Ont., confirmed the longtime use of graphite in that type of business as an additive to adjust the carbon level of steel. New technology has seen graphite applied in a different way, however. Because of the mineral’s ability to withstand expansion and contraction under varying degrees of heat, it is being used to make equipment used in steel making.

“Many components, sensors, have a graphite composition to give durability to those parts and devices under extreme conditions,” William Gair, manager of communications and media relations, said. Three graphite forms

Natural graphite is found in three forms: amorphous, vein and flake. Amorphous particles are described as being soft and irregular in shape, while vein graphite is lumpy with particles varying in size from miniscule on up to coarse flakes or chips. The flake variety has a flat plate or flaky appearance.

Of the different forms, the flake variety appears to be the one growing in popularity. “The evolution of the market for natural graphite, over the last 10 years, has translated into reduced exports for recognized microcystalline (powder- like) graphite producers,” writes Roche. “Inversely, Brazil and China experienced sizeable shipment increases, principally of the flake category.”

Major buyers of graphite include the Japanese, Americans and Europeans, and Roche makes the case that China and Brazil have been able to strengthen their market positions in flake graphite in these areas because of perceived supply insecurity elsewhere. “Coarse flake graphite is considered a strategic material in several countries,” writes Roche.

With flake graphite, size is important, and the bigger the flake the more its value, the federal government’s Boucher said. Deposits of flake graphite have also been more difficult to locate, which also places the flake form in greater demand. In its flake form, graphite expands or exfoliates readily (up to 400 times its bulk volume) and as such is finding much favor as a heat retardant.

Pricing graphite is not an easy task (there is a diversity of specifications plus the expected producer secrecy), but Roche writes that actual prices for coarse graphite flakes range between $500(US) and $1,000 per ton. Fine flake graphite sells in the $300-$800 range, with the microcystalline type worth $100-$150. The more pure product ranges between $1,200 and $3,500.

The U.S. Bureau of Mines reports that for 1987, graphite prices, as measured by the price of imports, averaged $712 per ton of crystalline flake graphite, compared with $648 the year before. Mexican amorphous graphite sold for $52, up from $49 in 1986.

As for grades of deposits, Boucher said 7-16% graphitic carbon is considered a medium grade, while 16-30% is high grade.