- Phosphate rock
Phosphate rock or
phosphorite is a general description applied to several kinds of rock which contain significant concentrations ofphosphate minerals , which are minerals that contain thephosphate ion in their chemical structure.Many kinds of rock contain mineral components containing
phosphate or otherphosphorus compound s in small amounts. However, rocks which contain phosphate in quantity and concentration which are economic to mine asore for their phosphate content are not particularly common. The two main sources for phosphate areguano , formed frombird droppings, and rocks containing concentrations of the calcium phosphate mineral,apatite .The United States is the world's leading producer and consumer of phosphate rock, which is used to manufacture phosphate
fertilizer and industrial products.China , theUnited States andMorocco are the world's largest miners of phosphate rock, each producing about a quarter of the total world production. Other countries with significant production includeBrazil ,Russia ,Jordan andTunisia . Historically, large amounts of phosphates were obtained fromguano deposits on small islands such asNauru ,Banaba andChristmas Island , but these sources are now largely depleted.Phosphate rock is mined, beneficiated, and either solubilized to produce wet-process
phosphoric acid , or smelted to produce elemental phosphoric acid or smelted to produce elementalphosphorus . Phosphoric acid is reacted with phosphate rock to produce the fertilizer triplesuperphosphate or withanhydrous ammonia to produce theammonium phosphate fertilizers. Elemental phosphorus is the base for furnace-grade phosphoric acid, phosphorus pentasulfide,phosphorus pentoxide , andphosphorus trichloride . Approximately 90% of phosphate rock production is used forfertilizer and animal feed supplements and the balance for industrial chemicals.For general use in the
fertilizer industry, phosphate rock or its concentrates preferably have levels of 30% phosphorus pentoxide (P2O5), reasonable amounts of calcium carbonate (5%), and <4% combinediron andaluminium oxides. Worldwide, the resources of high-grade ore are declining, and the beneficiation of lower grade ores by washing, flotation and calcining is becoming more widespread.References
* [http://www.australianminesatlas.gov.au/info/aimr/phosphate.jsp Australian Mineral atlas]
* [http://minerals.usgs.gov/minerals/pubs/commodity/phosphate_rock US Geological Survey]
* [http://minerals.usgs.gov/minerals/pubs/commodity/phosphate_rock/stat USGS Statistics]
* [http://www.pir.sa.gov.au/minerals/geology/commodities/phosphate PIRSA website]
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