Fluorspar extraction

World P.R. China Mexico South France Italy Africa Great Britain Spain USA Mongolia Fortner States of USSR 

1993 Prices Mexico/South Africa 100-112 /t, China 89-97 /t. Northern Europe 105-110 /t 

Mexico and South Africa have clearly lost market share to China, which has very good quality and inexpensive fluorspar (extraction in Mexico in 1987 824 10- t). 

---

Silicon Reduction. The preparation of ferrovanadium by the reduction of vanadium concentrates with ferrosiUcon has been used but not extensively. It involves a two-stage process in which technical-grade vanadium pentoxide, ferrosiUcon, lime, and fluorspar are heated in an electric furnace to reduce the oxide an iron alloy containing ca 30 wt % vanadium but undesirable amounts of siUcon is produced. The siUcon content of the alloy is then decreased by the addition of more V2O5 and lime to effect the extraction of most of the siUcon into the slag phase. An alternative process involves the... 

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. 

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. 

Lithium, rubidium, and caesium.—F. C. Robinson and C. C. Hutchins 7 extracted all three alkalies—lithium, rubidium, and caesium—by decomposing the mineral with fluorspar in the following manner ... 

An intimate mixture of equal parts of finely ground lepidolite and fluorspar—say, 100 grms. lepidolite—is stirred with sulphuric acid in a lead or platinum dish so as to form a thin slip. When the fumes of silicon fluoride, etc., have nearly ceased to be evolved, heat the mixture on a sand bath or hot plate between 200° and 300° until the residue is dry and hard. Extract the mass with hot water until a few drops of the washings give no... 

The total reserves of economically and marginally economically workable fluorspar is ca. 311 10 t. The quantities extracted worldwide were ... 

Calcium fluoride (fluorspar) CaF2 is a very stable compound. The easiest way to decompose this is to mix the finely powdered sample with silica (or broken glass), and heat the mixture with concentrated H2SO4 in a platinum crucible. Silicon tetrafluoride gas is formed and can be detected (cf. Section 4.17, reaction 1). The residue contains calcium sulphate. This can be extracted with 5% sodium ethylenediamine tetraacetate in the presence of 2m ammonia, and calcium ions can be tested for in the solution (cf. Section 3.33). 

Chlorine, bromine, and iodine are found as the halides in seawater and in salt deposits. The concentration of iodine in these sources is very small, but it is concentrated by certain seaweeds. When they are harvested, dried, and burned, iodine can be extracted from the ashes. Fluorine occurs in the minerals fluorspar... 

---