Bureau of Mines / Minerals yearbook: Metals and minerals 1978-79
Year 1978-79, Volume 1 (1978-1979)
Pressler, J. W.
Gypsum, pp. 411-422 PDF (1.6 MB)
GYPSUM Table 9.—Gypsum: World production, by country —Continued 421 (Thousand short tons) Country1 1976 1977 1978" 1979e Asia: —Continued Vietname Oceania:Australia Total 11 T1,038 13 1,010 15 1,279 15 1,300 r73,610 79,042 84,586 81,954 eSetimate "Preliminary. rl~~ed. NA Not available. ' Gypsum is also produced by Romania, but production data are not available. 2lncludes anhydrite. 3Shipments. 4Reported figure. 5Excludes byproduct gypsum. 6lncludes byproduct gypsum. (In the case of Japan, series was revised to include estimates for byproduct gypsum, which represents virtually all gypsum consumed during 1976-79.) TECHNOLOGY A new system was patented in 1978 for anchoring mine roofbolts, using a gypsumbase cement that is cheaper than the organic resins now being used. The key ingredient in the new cementing system is specially encased water in waxy microcapsules. A free-flowing mixture of the droplets, plus dry gypsum-based cement with a chemical accelerator, is packed in sausage-shaped bags, and inserted in the hole drilled for the roofbolt. During drilling, a viscous paste is formed that hardens in 30 seconds and provides a pull strength of 8,000 pounds per foot of hole after 5 minutes.22 Heyward-Robinson Co. of New York, N.Y., a member of the Alusuisse Group of Switzerland, marketed in 1979 the hemihydrate process for the manufacture of wetprocess phosphoric acid developed by Nissan Chemicals of Japan. The byproduct gypsum is in such a form that it can be used directly in the production of plaster and as a set-retarder in cement production.23 In 1978, Central Glass Co. of Japan began marketing a glass fiber-reinforced, foamed gypsum product, which is expected to find its chief usage in fireproofing walls. The product was known as Partlex, and was claimed to be light, strong, adiabatic, and easily processed on a continuous basis. Insulation properties were very attractive, with fire resistance greater than ordinary lightweight concrete, and thermal conductivity only 10% of that of concrete.24 Japan can utilize more of its phosphogypsum and other calcium sulfate products of chemical and utility air and water desulfurization because it concentrates on processes that produce a much purer byproduct. The new Nissan process (discussed above) yields a hemihydrate byproduct gypsum that can be recrystallized to form the dihydrate. Similarly, the Nippon Kogan Kogyo process is a hemihydrate-dihydrate process. The Central-Prayon process also involves a recrystallization stage, but dihydrate is initially formed and then dehydrated to the hemihydrate form. Although both these processes are more expensive, it means that the byproduct gypsum may be used for plaster, wallboard, and as a set-retarder in cement.25 In Italy, research by the Universities of Florence and Bologna in 1978 has indicated the beneficial results of a soil conditioner on heavy clay soils. A soil conditioner of calcium sulfate, ferric sulfate with minor amounts of magnesium sulfate, and ferric oxide showed increases in the permeability of clay to air and water, decreased erosion and surface crusting and cracking, and reduced costs of cultivation and equipment maintenance.26 American Cyanamid Co. and Lemco, Inc., came to an agreement in 1979 to process and sell the byproduct gypsum produced at Cyanamid's titanium dioxide plant in Savannah, Ga. Lemco is building a plant to produce byproduct gypsum briquettes for the cement industry in the area.27 ' Physical sc entist, Section of Nonmetallic Minerals. 2p~ & Quarry. V. 72, No.4, October 1979, pp. 22-23. Rock Products. Industry News. V. 82, No.6, July 1979, p. 3Tazairt, A. The New Gypsum Plant at Fleurus, Algeria. Zement-Kalk-Gips (Wiesbaden). No. 8, August 1978, pp. 187-189 (translation of No. 6, June 1978). 4Keller, J. Sulphur Report. V. 14, No.4, December 1978, p.2. 5Coope, B. Australia's Industrial Minerals. md. Miner. (London). No. 142, July 1979, p. 41. 6Manos, A. Industrial Minerals of Botswana. hid. Miner. (London). No. 130, July 1978, p. 53. 7Canadian Mineral Survey. Department of Energy, Mines and Resources, ottawa, Canada. 1978, p. 74, and 1979, p. 64.
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