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Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% [1] to 20% phosphorus pentoxide (P 2 O 5). Marketed phosphate rock is enriched ("beneficiated") to at least 28%, often more ...
Phosphate mine near Flaming Gorge, Utah, US, 2008 Train loaded with phosphate rock, Métlaoui, Tunisia, 2012. Phosphates are the naturally occurring form of the element phosphorus, found in many phosphate minerals. In mineralogy and geology, phosphate refers to a rock or ore containing phosphate ions.
Branched polyphosphoric acids give similarly branched polyphosphate anions. The simplest example of this is triphosphono phosphate [OP(OPO 3) 3] 9− and its partially dissociated versions. The general formula for such (non-cyclic) polyphosphate anions, linear or branched, is [H n+2−k P n O 3n+1] k−, where the charge k may vary from 1 to n + 2.
Fluorapatite as a mineral is the most common phosphate mineral. It occurs widely as an accessory mineral in igneous rocks and in calcium rich metamorphic rocks. It commonly occurs as a detrital or diagenic mineral in sedimentary rocks and is an essential component of phosphorite ore deposits.
The white allotrope can be produced using several methods. In the industrial process, phosphate rock is heated in an electric or fuel-fired furnace in the presence of carbon and silica. [6] Elemental phosphorus is then liberated as a vapour and can be collected under phosphoric acid.
US production of phosphate rock peaked in 1980 at 54.4 million metric tons. The United States was the world's largest producer of phosphate rock from at least 1900, up until 2006, when US production was exceeded by that of China. In 2019, the US produced 10 percent of the world's phosphate rock. [89]
Phosphogypsum (PG) is the calcium sulfate hydrate formed as a by-product of the production of fertilizer, particularly phosphoric acid, from phosphate rock. It is mainly composed of gypsum (CaSO 4 ·2H 2 O).
Apatite is also found in clastic sedimentary rock as grains eroded out of the source rock. [7] [8] Phosphorite is a phosphate-rich sedimentary rock containing as much as 80% apatite, [9] which is present as cryptocrystalline masses referred to as collophane. [10] Economic quantities of apatite are also sometimes found in nepheline syenite or in ...