Graphite for crucible use must be high grade, either lump, chip, or flake graphite, contain at least 85 per cent. graphitic carbon and be free from fluxing impurities. Vein graphite is considered especially desirable for this use. Possibly the increased development of the electric furnace in the steel industry and in non-ferrous metallurgy will reduce the demand for crucibles. Both crystalline and amorphous graphite are used as lubricants. For this purpose the graphite should be free from quartz or other gritty impurities. For foundry facings, amorphous graphite and Ceylon dust are chiefly used; high-grade material is not required. For the better grades of pencils, mixtures of crystalline and high-grade amorphous are needed; for the poorer grades, amorphous is used alone. The graphite used as polish for high explosives is amorphous. This use does not consume large amounts. For the manufacture of electrodes, artificial graphite is considered the most suitable. The graphite used as dry battery filler may be either amorphous, artificial or crystalline. Pure material is required, but the size of grain is not a factor.
Amorphous graphite is used in boiler compounds for preventing hard scale; pure material is not essential. For paints, either amorphous or crystalline graphite may be used and need not be high grade.
For stove polish and shoe polish amorphous graphite is chiefly used; imperial graphite is used as an adulterant in fertilizers, to give the desired dark color.
For amorphous graphite and dust, artificial graphite may be substituted. For crystalline graphite used in the manufacture of crucibles no good substitute is available. However, the use of electric furnaces or open-flame furnaces in non-ferrous metallurgy may reduce the need of crucibles. For lubricating, mica is used in somewhat the same way as graphite but is much inferior. Many other boiler compounds serve the same purpose as graphite. In paints, lampblack is a substitute. Talc is used in connection with and as a partial substitute for graphite in foundry work. Blast furnace graphite, or “kish,” offers possibilities as a substitute for flake graphite for lubricating purposes. Developments along this line, however, have not proceeded far enough to be conclusive.
GEOLOGICAL OCCURRENCE
Amorphous graphite may occur wherever coal or other carbonaceous beds have undergone regional or igneous metamorphism. Crystalline graphite has two principal geologic occurrences, as flakes in schists and as larger crystals in veins. Flake graphite in schists is usually associated with granitic intrusions which appear to have aided recrystallization of original carbonaceous material in the sediments. Vein graphite in commercial quantities is rather rare. It is found associated with granitic intrusives and generally with graphitic sediments containing the flake variety. Such rocks in most parts of the world have not been prospected enough to make sure that all important bodies of graphite are discovered.
WORLD CAPACITY FOR GRAPHITE PRODUCTION
In the order of their importance the following table lists the various countries which produce graphite or in which graphite deposits have been reported:
- 1. Crystalline Graphite
- A. Vein Graphite
- Ceylon—could produce up to 35,000 short tons per year, all grades.
- United States—small production from Montana.
- Canada—small amount recently produced.
- B. Flake Graphite
- Madagascar—could produce up to nearly 50,000 short tons per year.
- Bavaria—has averaged 12,000 tons for several pre-war years, and greatly increased production during the war. Produced 40,000 metric tons in 1917.
- United States—could readily produce 4,000 tons of flake exclusive of dust.
- Canada—could probably produce 1,200 tons of flake exclusive of dust.
- Spain—deposits being developed.
- Norway—new development reported.
- Roumania—important deposits recently reported.
- Japan—has not produced very much.
- Sweden—very small production.
- Transvaal—very small production, locally consumed.
- Greenland
Brazil - —large deposits reported. Very little development. - German East Africa (former)—deposits of supposed large extent reported.
- 2. Amorphous Graphite
- German Austria
Czecko-Slovakia - —has long produced large amount of graphite annually. - Chosen—could probably produce 12,000 tons per annum.
- Italy—could probably produce 12,000 tons per annum.
- Mexico—could probably produce 6,000 tons per annum.
- United States—could readily produce 6,000 tons natural and 6,000 tons artificial amorphous graphite.
- Spain—could probably produce 1,000 tons annually.
- France—could probably produce 1,000 tons annually.
- Siberia—large amount available but undeveloped.
- Rhodesia—local supply.
- Brazil—supply undeveloped.
- Queensland—supply undeveloped.