Apatite ores

The dynamics of extraction of apatite ores

APATITE ORES (EN: apatite ores; DE: Apatiterze; FR: minerais d'apatite; ES: minerales de apatita; RU: апатитовые руды) are the natural mineral aggregates, which are containing apatite in such quantity and in such form, that its extraction into concentrate is technologically possible and economically feasible.

They sub-divide apatite ores according to the content of P2O5 into the rich (more than 18%), poor (5-8%) and miserable (3-5%); within the complex ores, apatite may be available as the main component or one of the major ones, the second-degree one, or as the companion impurity (usually non-significant). According to the conditions of formation of deposits of apatite ores and complex apatite-bearing ores, they sub-divide these ores into the endogenous, exogenous, and metamorphosed ones. They distinguish among the endogenous ones the magmatic, carbonatitic, pegmatitic, contact-metasomatic, hydrothermal, and volcanogenic-sedimentary deposits, which are grouped into several ore formations. They are associated with magmatic rocks of the central intrusions of agpaitic nephelinic syenites, of ultrabasic alkaline rocks, of alkaline gabbroids, of alkaline and nephelinic syenites. They refer to exogenous ones the deposits of weathering, which are confined to the formation of the weathering crust on carbonatitic and camaphoritic substrates. The metamorphosed deposits are confined to the apatite-quartz-diopside and apatite-dolomitic formations.

There have the greatest industrial importance the magmatic and carbonatitic deposits. There are especially significant the accumulations within the massifs of alkaline magmatic rocks, within which the apatite-bearing property is characteristic for the formations of the central intrusions of agpaitic nephelinic syenites. Within the USSR, it is represented with the Khibinskiy and Lovozerskie plutons, which are largest within the world, and with the smaller Soustov's massif. Apatite ores consist of the following minerals: apatite, nepheline, pyroxene, feldspar, sphene, but in various quantitative proportions, and with various textural peculiarities. The content of P2O5 within the ores is 16-19%. There belong to agpaitic complexes abroad the Illimausak massifs (Greenland), Pilanesberg (South Africa), Los (Guinea), Saint-Hilaire (Canada), and others.

The formation of ultrabasic alkaline rocks with carbonatites manifests itself both on platforms (shields), and within the consolidated folded regions within the regional fault zones. It is represented with the complex multiphase intrusions of the central type, which are characterized by the zone-ring structure of individual series of rocks, which were forming themselves mainly at the shallow depths. Within the USSR, the operation of the apatite-bearing deposit, which is associated with this formation, is performed only within the Kovdor massif on the Kola peninsula. The mineral composition of the apatite-magnetite ores is: magnetite, apatite, forsterite, phlogopite, calcite, dolomite; sometimes there are noted the baddeleyite, sulfides. The content of P2O5 is 5.3-7.2%.

The alkaline-gabbroid formation is represented with the Oshurkovskoe deposit (Buryat ASSR). The large part of the massif is formed with diorites and metasomatic transformed rocks of syenite-dioritic composition. All rocks are apatite-bearing. The apatitic mineralization has been traced down to the depth of 600 metres. The mineral composition of the ores is: apatite, plagioclase, potassic feldspar, hornblende, biotite, titanomagnetite, sphene, and zircon. The average content of P2O5 within the apatite-siliceous ores is approximately 4%.

There is associated with the apatite-bearing metamorphogenic formations, for example, the Seligdarskoe deposit of apatite-dolomite ores (Yakut ASSR); the ores lay here at the intersection of disruptions of the north-eastern and north-western directions, among the crystalline schists and gneisses, in the form of steeply dipping stock-shaped body, which may be traced down to the depth of 1600 metres. The content of P2O5 is 5-6% on average. The mineral composition of the ores is: apatite, dolomite, sometimes quartz, martite, hematite, calcite, muscovite.

Industrial concentrations of apatite of the weathering crust are identified at the Beloziminskoe and Kovdorskoe deposits; abroad, the deposit of similar type is known within Finland (Sokli). The mineral composition of the ores is: apatite, hydro-micas, ochres (ferruginous and carbonatic). Depending on the component composition and textures, there are distinguished numerous mineral types of apatite ores: apatite-nephelinic, magnetitic, rare-metal-carbonatic, siliceous, ilmenite-titanomagnetitic, copper-sulfide-titanomagnetitic, phenolitic, dolomitic, francolitic, rare-metal-ochrous ores, and others. The quality of apatite ores is evaluated according to the content of P2O5 and impurities. During the development of apatite deposits with underground method, there is used mainly the system of the forced level caving with the breaking-out of the ore with horizontal fan-shaped boreholes, and at the open pit mines, there is used commonly the system of the transverse entries without the incision tranches (lower horizons are unsealed using the fan-shaped ramps on the laying side of the ore body).

The primary method of beneficiation of apatite ores is flotation. The absorbents are the fatty acids (pH 9-9.5), soaps of the resin acids and sulfatic one, tall oil crude and distilled, mixture of soapstock and sulfatic soap, oxidized petrolatum and kerosene, amines, and others; the foamers are the pine oil, alcohols, flotanol; the regulators of the environment are the Na2CO3, NaOH, Na2SiO3; the depressors are the hexametaphosphate, russified starch. The process of condensation of apatite concentrate is intensified using the feed of coagulants (for example, of the 5% solution of ferrous sulfate). There are also used the magnetic and electrical separation, gravity and radiometric methods of beneficiation, roasting, and also auxiliary operations, namely, disintegration, classification within various apparatuses, and others. There may be obtained from the ores of all types the concentrates with content of P2O5 of 30% and more, with extraction of 65-98%; there belong to the most easily beneficiated ones the apatite-siliceous ores (apatite-nephelinic, apatite-aegirinic, and others), to the refractory ones the substantially carbonatic ones and the ores of the weathering crust, which are requiring the usage of the branched and labour-consuming technological schemes. Within the USSR, there are comprehensively processed the ores of the Volkovskij (Cu, Fe, Ti, with V and R as the by-products), of the Kovdorskiy (Fe, Zr, P), and partially of the Khibinskaya group of deposits. There is extracted at the latter in the small quantity (15%) the nephelinic concentrate (29.5% Al2O3). The major reserves of apatite ores are concentrated within the USSR. Besides the ones, which are recited above, there are best known the deposits of apatite ores Dzhugdzhurskoe (apatite-ilmenite-magnetitic), Maganskoe (apatite-nephelinic), and Esseiskoe (calcite-magnetite-forsteritic) at the west coast of Sea of Azov, Volkhovskoye (within olivinites with sulfides) at the Middle Urals, and others. (The dynamics of the extraction of apatite ores, and of the production of concentrate within the USSR are shown on the Figure). Among the other socialistic countries, the largest deposits are located within Vietnam (Laokayskiy apatite-bearing basin).

There have the largest reserves of apatite ores the Brazil, South Africa, Finland, Uganda, Norway, Zimbabwe, Canada, Spain, India. In 1980, the annual extraction of apatite ores within the industrially developed capitalistic and developing countries has amounted to 6.63 million tonnes. The major extracting countries are: the South Africa, Zimbabwe, Brazil, and others.

Apatite ores are used primarily for the production of mineral fertilizers (superphosphate, monoammonium phosphate, and others). Besides this, apatite ores are the raw material for the obtainment of the phosphate acid, yellow phosphorus, various salts; it is used for metallurgy, for ceramics, glass, and chemical industries.