Fluorspar solubility

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). 

The commercial product is obtained from naturally occurring mineral fluorspar, which is purified and powdered. Also, it may be precipitated by mixing a solution of sodium fluoride with a soluble calcium salt ... 

Numerous processes have been proposed for extracting potash from felspar, leucite, alunite, and other minerals rich in this substance, but the cost is so great that very few proposals yet made ofier promise of successful competition with the Stassfurt deposits. This is even the case with alunite, where mere calcination to 1000° drives off water and sulphuric acid, leaving water-soluble potassium sulphate, and alumina. Humphry Davy in his paper On Some Chemical Agencies of Electricity (1807), indicated in Cap. Ill, found that when water was electrolyzed in cavities contained in celestine, fluorspar, zeolite, lepidolite, basalt, vitreous lava, agate, or glass, the bases separated from the acid and accumulated about the cathode. It is therefore probable that if water with finely divided potash minerals in suspension were electrolyzed, the alkali would be separated in a convenient simple way. 

Kohlrauch ( ) reported the solubility of CaF2 and fluorspar, which yield solubility products of 3.6 x 10 and 2.8 x 10... 

In the wet processes poorly soluble uranium compounds are precipitated, whereby the fluoride left in the filtrate is reacted with lime to fluorspar or processed to other inorganic fluorine compounds by fluorine processing companies. 

Derivation (1) By powdering pure fluorite or fluorspar (2) by the interaction of soluble calcium salt and sodium fluoride. 

Chloride is a major anionic component of the biomass. Fluorine occurs in sparingly soluble mineral deposits such as fluorite and fluorspar (CaFi), cryolite (NasAlFe), and fluorapatite (Ca5(P04)3F). The most easily oxidized halogen element, the iodine, is also found in iodates. 

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