METHOD OF PRODUCING WET-PROCESS PHOSPHORIC ACID Russian patent published in 2009 - IPC C01B25/22 

FIELD: chemistry.

SUBSTANCE: invention relates to dihydrate methods of producing wet-process phosphoric acid, used in production of mineral fertilisers. The method of producing wet-process phosphoric acid using a dihydrate method involves decomposition of phosphate raw material with a mixture of sulphuric and phosphoric acid in the presence of recycled pulp and crystallisation of calcium sulphate in a multisection extractor with separation of pulp decomposition and ageing steps, cooling extraction pulp using a vacuum method, separation of pulp through filtration obtaining phosphoric acid product, countercurrent washing calcium sulphate with return of the washing solution to the phosphate decomposition stage. The decomposition step is carried out in zones, where in the zones for introduction of phosphate raw material, basic decomposition of phosphate with crystallisation of calcium sulphate and for cooling pulp, content of SO₃ in the liquid phase of the pulp is kept at the level 17 to 22; 22 to 25 and 25 to 30 g/l at volume ratio of reaction mass in these zones of 1:(2 to 5):(1 to 2), respectively, and circulation of pulp from the cooling zone to the zone for introduction of phosphate raw material is kept in the volume 5000 to 12000 m³/h. Phosphate raw material is introduced in form of a mixture with a dilution solution or extraction pulp. Sulphuric acid in the cooling zone is introduced into the stream of cooled pulp.

EFFECT: method intensifies process of producing wet-process phosphoric acid by increasing output of the system, increases efficiency of processing phosphate raw material, stabilises and simplifies the process.

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