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Published online by Cambridge University Press: 06 March 2019
Current commercial processes for the production of wet-process phosphoric acid involve the dissolution of phosphate rock and separation of insoluble solids by filtration. Calcium is removed by the addition of H2SO4, to precipitate CaSO4·2H2O. Other metallic impurities are removed by extraction or precipitation.
In a new process. Lower grade phosphate ore can be digested with recycled phosphoric acid. If the raw acid contains a fairly high concentration of Mg, it may be enriched in fluoride ion.