Fluorspar, also called fluorite, is a calcium fluoride mineral CaF2. In some cases it may include additions of yttrium (Y) – 15-40%, manganese (Mn), strontium (Sr) – no more than 0.1% and other rare-earth elements. Its density is 3.18 g/cm³ and hardness according to the Mohs scale is 4. The information is confirmed by the specialists of this company: https://towingandscrapcarremoval.ca/scrapyard-toronto/.
The structure of the crystals is of the ionic type. The Ca2+ cations form a very dense cubic lattice, with all the unoccupied space in the form of a tetrahedron filled with F- ions. It exists in nature as cubic or octahedral crystals, both granular and solid aggregates.
The shades of feldspar are quite different, among which can be found: purple, black, blue, green, purple, and so on. There are also colorless types, and even polychromatic ones.
The stone has a bright luminescence under the UV rays (the hue is caused by the inclusions of rare-earth elements). In addition, the luminescence of a stone under the action of heat is noticed.
The mineral is most commonly found in hydrothermal and metasomatic deposits between carbonate rocks, but very rarely in sedimentary soils.
Calcium fluoride is used to produce hydrofluoric acid (HF) and sodium hexafluoroaluminate (Na3[AlF6]), which is used in the aluminum industry, as a flux in ferrous and non-ferrous metallurgy, as an additive in the manufacture of glass, enamels and glazes.
The largest share of fluorite is used to create anhydrous hydrogen fluoride and hydrofluoric acid, which are used to produce chemical elements with a more complex structure, in which fluorine, fluorinated hydrocarbons, freons, and fluorolones predominate. Global consumption of hydrofluoric acid has passed the 660,000-tonne-per-year mark and is growing. To produce hydrofluoric acid, high-quality grades of fluorspar concentrates containing more than 92% calcium fluoride (CaF2) are required. The highest-quality concentrates containing more than 97% calcium fluoride (CaF2) are required to produce anhydrous hydrofluoric acid.
The second largest use of calcium fluoride is in the form of flux in ferrous metallurgy. Metallurgical grades of fluorite should include more than 65% of calcium fluoride (CaF2), but their technical requirements for use set the mandatory size of fluorite pieces (up to 5 cm – not more than 10%). It is very difficult to maintain the required purity of the material, having quite a lot of lumps of fluorite, and grades of fluorspar exist in insufficient quantities, so they are scarce. A large proportion of the fluorspar concentrate sold is small in size. To increase the size of pieces, pelletizing and briquetting are used, which in turn makes the finished product more expensive.
The last application of calcium fluoride is its use as an additive element in welding electrodes. It strengthens the strength and quality of the resulting welds. To produce high quality welding materials, fluorspar raw material is combined with gra
vitational and flotation fluorite concentrates. Such process is accompanied by the strictest requirements for inclusions of harmful additives: sulfur (S) – not more than 0,1 %, phosphorus (P) – not more than 0,1 %. Types of naturally occurring fluorite ores that include small portions of sulfur are very rare, so it is sometimes impossible to produce a sufficiently high-quality electrode concentrate.
– In the nuclear industry to extract uranium fluoride (UF4), which is a transition product in the process of enrichment and regeneration of nuclear fuel;
– During glass melting – to lower the melting temperature and increase transparency, and for enamels – to lower the melting temperature and give them a hue;
– in cement production – to lower firing temperatures of clinker composition and increase quality characteristics;
– to impregnate wood with NaF to prevent deterioration;
– for etching of metals and glass;
– treatment of boreholes in oil wells to increase oil production.