Fluorspar calcium fluoride

Winkelmann and Straubel20 carried out a similar experiment, but they were fortunate in using fluorspar (calcium fluoride) instead of... 

A basic step in hydrofluoric acid manufacture is the reaction of sulfuric acid with fluorspar (calcium fluoride) to produce hydrogen fluoride and calcium sulfate. Spent alumina is also generated by the defluorination of some hydrofluoric acid alkylation products over alumina. It is disposed of or sent to the alumina supplier for recovery. Other solid residuals from hydrofluoric acid alkylation include any porous materials that may have come in contact with the hydrofluoric acid. 

F 94.96%, H 5.04%. HF. Obtained by the action of sulfuric acid on fluorspar (calcium fluoride) Faith, Keyes Clark s Industrial Chemicals, F. A. Lowenheim, M. K-Moran, Eds. (Wiley -Interscience, New York, 4th ed., 1975) pp 462-467 prepn of pure HF Simons, Inorg. Syn. 1, 134 (1939) Shamir, Netzer, J. Set Instrum. (Ser. 2) 1, 770 (1968). Exists as hydrogen-bonded polymers Simons,... 

Continuous sulphuric acid breakdown processes are possible in which the acid and ore are fed together at the top of a rotating, inclined, heated kiln. The reaction products and excess sulphuric acid can then be removed continuously from the lower end. It is necessary that the reactants and products shall not be sufficiently mobile for by-passing to take place when flowing down the reactor, otherwise residence times will vary widely about the mean value. A kiln of this type resembles that commonly used for the manufacture of hydrofluoric acid by the reaction of sulphuric acid with fluorspar (calcium fluoride). 

Fluorine is at the top of the column (VII A) in the Periodic Table known as the halogens or salt formers. Chlorine, bromine, iodine, and astatine are also in the halogen group. Halogens easily accept electrons from other atoms and combine with metals to form salts. In nature, fluorine is found in ores of fluorspar (calcium fluoride) and cryolite (a combination of sodium, fluorine, and aluminum). In the body, fluorine is found in the blood, bones, and teeth. Many communities in the United States add small amounts of fluorine to drinking water, since the presence of fluorine has been found to prevent the formation of cavities in teeth. 

In the geochemistry of fluorine, the close match in the ionic radii of fluoride (0.136 nm), hydroxide (0.140 nm), and oxide ion (0.140 nm) allows a sequential replacement of oxygen by fluorine in a wide variety of minerals. This accounts for the wide dissemination of the element in nature. The ready formation of volatile silicon tetrafluoride, the pyrohydrolysis of fluorides to hydrogen fluoride, and the low solubility of calcium fluoride and of calcium fluorophosphates, have provided a geochemical cycle in which fluorine may be stripped from solution by limestone and by apatite to form the deposits of fluorspar and of phosphate rock (fluoroapatite [1306-01 -0]) approximately CaF2 3Ca2(P0 2 which ate the world s main resources of fluorine (1). 

Grades, Quality Control. Fluorspar is marketed ia several grades metallurgical fluorspar (metspar) is sold as gravel, lump, or briquettes. The minimum acceptable assay is 60% effective calcium fluoride. The effective value is determined by subtracting from the contained calcium fluoride 2.5% for every percent of Si02 found ia the complete analysis apparently based on the following stoichiometry (1) ... 

Imatra Also called the Solid Lime Process. A method for desulfurizing steel made by an electric arc process. Additions are made of burnt lime (calcium oxide), fluorspar (mineral calcium fluoride), and ferro-silicon. 

In his first paper3 , Stokes called the observed phenomenon dispersive reflexion, but in a footnote, he wrote I confess I do not like this term. I am almost inclined to coin a word, and call the appearance fluorescence, from fluorspar, as the analogous term opalescence is derived from the name of a mineral. Most of the varieties of fluorspar or fluorspath (minerals containing calcium fluoride (fluorite)) indeed exhibit the property described above. In his second paper7, Stokes definitely resolved to use the word fluorescence (Scheme 1.2). 

Compounds Sodium fluoride calcium fluoride fluorspar cryolite... 

Calcium fluoride occurs in nature as the mineral fluorspar or fluorite. It is used as a flux in ferrous metallurgy to enhance the fluidity of the slag. An important application of this compound is in the manufacture of fluorine and hydrofluoric acid, starting materials for producing many fluoroorganics. It also is used in glass and ceramics. Pure crystals are used in lasers, optics, and electronics. Other applications are in high temperature, dry-film lubricants ... 

DeCaF treats soil, sludges, solids (e.g., slag), residues, and sediments contaminated with radioactive elements and other hazardous constituents. The technology has potential applications in the treatment of heavy metals. The technology can treat uranium-contaminated calcium fluoride matrices, rare-earth ore residues, and fluorspar contaminated with uranium. The technology can also extract more complex fluoride by-products. 

Fluorspar or Fluorite See under Calcium Fluoride in this Section... 

Hydrogen Fluoride. Anhydrous hydrogen fluoride is generally prepared by action of concentrated sulfuric acid on calcium fluoride Fluorspar (>98% CaF2). The estimated world production is about 1 million tons mostly to... 

The importance of fluorine lies largely in the use of several compounds of that element. Calcium fluoride, or fluorspar (CaF2), is used as a flux and, like sodium fluoride (NaF), as an insecticide. Ammonium fluoride (NH4F) is used as a disinfectant hydrofluoric acid is used in the etching of glass and organic compounds are used as commercial refrigerants. 

Calcium bromide and calcium iodide are sold as hexahydrates for use in medicine and photography. Calcium fluoride (CaF2) occurs naturally as fluorspar. 

The world production of calcium fluoride remains between 4 to 5 million metric tons and the market price is 97— 110/ton. Currently, over 33% of the world s requirement of fluorspar comes from China. 

Cadmium compounds Calcium fluoride (fluorspar) Carbon disulfide Carbon tetrachloride Chloral hydrate Chlorine poison gas Chlorobenzene Chloroform... 

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