Apatite

The extraction of apatite ores

APATITE (from the Greek word "apate" (deception), because apatite was often mistaken for other minerals * EN: apatite, calcium phosphate; DE: Apatit; FR: apatite; ES: apatita; RU: апатит) is the mineral of the class of phosphates, Ca5[PO4]3(F,Cl,OH)2. It has variable quantity of F-, Cl-, (OH)-, CO32-. There are noted within the certain apatites the impurities of Mn (up to 7.6% of MnO), Sr (up to 23.7% of SrO), Mg (up to 0.5% of MgO), Fe (up to 4.6% of FeO + Fe2O3), Al (up to 1.5% of Al2O3), TR (up to 12% of TR2O3), Th (up to 0.6% of ThO2); within the anionic part, the impurities of CO2 (up to 4.5%), SO3 (up to 3.7%), SiO2 (up to 2%).

Depending on the composition, they distinguish: fluorapatite, chlorine apatite, hydroxylapatite, carbonate apatite (podolite, kurskite), fluorine-carbonate apatite (francolite or staffelite), and others. There have the widest distribution and practical significance the fluorapatite and fluorine-carbonate apatite. The theoretical content of P2O5 within apatite is 42.3%. It crystallizes into the hexagonal crystal system, forming elongated, prismatic to acicular, less often tabular crystals. The aggregates are: grainy, sometimes bud-shaped, earthy, oolitic, and others. Physical and optical properties of apatite vary with dependence on composition of mineral. The colour of apatite is caused by the availability of impurities or defects of structure: blue, blue-green, yellow-green, pink in case of substituting Ca2+ to Mn3+ (depending on concentration of the latter); blue in case of the availability of 0- hole centres; in case of the availability of significant quantities of inclusions of hematite the colour is dark red, of organic substances the colour is black, of clayish substances or hydroxides of Fe the colour is gray, brown. The cleavage is practically absent, the lustre is vitreous, fatty. The hardness is 5. The density is from 2950-3200 to 3800 kilograms per cubic metre. It is genetically associated with various magmatogenic metamorphic and sedimentary complexes.

Apatite-nepheline plant

Apatite is the typical widely distributed accessory mineral of the magmatic rocks. It may be found within the alkaline, acidic, and basic pegmatites, within the certain high-temperature deposits of iron ores, within the high-temperature hydrothermal and alpine type veins, within the regional- and contact-metamorphosed rocks (mainly within the crystalline limestones). Exogenous apatite is the product of de-crystallization of phosphorites. Industrial accumulations of apatite are rare; at the same time, apatite ores proper are extracted at 10-12 deposits only, while they obtain apatites at the remaining deposits as the by-product during the processing of the rare metallic and iron (apatite-magnetite) ores. The major deposits are associated with nephelinic syenites. For the main types of deposits, beneficiation and usage, see within the "Apatite ores" article.