Fluorspar And Cryolite (21a84ea9-d225-49fb-8578-f562b0457b96)

Fluorspar is the commercial name for fluorite, a mineral that is calcium fluoride, CaF2. The name, derived from the Latin word fluere (to flow), refers to its low melting point and its early use in metallurgy as a flux. It is the principal industrial source of the element fluorine. Cryolite, sodium aluminum fluoride, Na3AlF6, is a rare mineral which has been found in commercial quantities only in Greenland. The natural material has been supplanted by synthetic cryolite for its principal industrial use in the manufacture of aluminum. History Fluorspar was used by the early Greeks and Romans for ornamental purposes as vases, drinking cups, and table tops. Various peoples, including the Chinese and the American Indians, carved ornaments and figurines from large crystals. Its usefulness as a flux was known to Agricola in sixteenth century Europe. Fluorspar mining began in England about 1775 and at various places in the United States between 1820 and 1840. Production grew substantially following the development of basic open-hearth steelmaking, wherein it is used as a flux. Use was stimulated by growth of the steel, aluminum, chemical, and ceramic industries, particularly during World Wars I and II. Fluorocarbons entered the picture in 1931. The use of anhydrous hydrogen fluoride (HF) as a catalyst in the manufacture of alkylate for high octane fuel began in 1942. Differential flotation for separating fluorspar from galena, sphalerite, and common gangue minerals in the 1930s, and the application of heavy-media concentrating methods to the treatment of low-grade ores in the 1940s were outstanding technological advances that facilitated increased production. Recently, pelletizing and briquetting of flotation concentrates for use in steel furnaces and the development of flotation schemes for beneficiating ores containing abundant dolomite and barite have been major improvements in the industry. Uses of Fluorspar Fluorspar is used to make hydrogen fluoride, also called hydrofluoric acid, an intermediate for fluorocarbons, aluminum fluoride, and synthetic cryolite. It is used as a flux in the steel and ceramic industries, in iron foundry and ferroalloy practice, and has many minor specialized uses. Hydrogen fluoride (HF) is produced by reacting acid grade (97% CaF2) fluorspar with sulfuric acid in a heated kiln or retort to produce HF gas and calcium sulfate. After purification by scrubbing, condensing, and distillation, the HF is marketed as anhydrous HF, a colorless fuming liquid, or it may be absorbed in water to form the aqueous acid, usually 70% HF. Synthetic cryolite, organic and inorganic fluoride chemicals, and elemental fluorine are made from hydrofluoric acid. The acid itself is important in catalysis in the manufacture of alkylate, which is an ingredient in high-octane fuel for aircraft and automobiles, in steel pickling, enamel stripping, glass etching and polishing, and in various electroplating operations. The manufacture of one ton of virgin aluminum requires about 50 to 60 lb of fluorine content in synthetic cryolite and alumnium fluoride. This quantity, through improved technology and recovery practices, is being lowered significantly.