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

FIELD: chemistry.

SUBSTANCE: present invention relates to methods of obtaining wet-process phosphoric acid. The method of obtaining wet-process phosphoric acid involves decomposition of phosphate raw materials in a multiple-zone extractor with phosphoric and sulphuric acid in the presence of recycled pulp, obtaining calcium sulphate pulp in phosphoric acid, its maturation, cooling the pulp in air in frothy conditions, separation of the product from calcium sulphate residue by filtration, washing the residue in a water counter-flow with obtaining circulating phosphoric acid and returning it to the decomposition stage. The pulp obtained from the decomposition stage is cooled and taken in amount of 30-100% of the circulating pulp at this stage. Cooling is done by blowing air under grid at volume ratio of air to pulp in the coolant of 2.5-18.0 and water concentration of the coolant grid of 800 - 2800 m³/(m²·h). The obtained gas-solid-liquid dispersion is fed into the free volume under the cover of the extractor. Pulp at temperature 89 - 96°C and 80 - 90°C is cooled respectively, during polyhydrate and dehydrate production wet-process phosphoric acid. Cooling is done at temperature gradient between the pulp taken for cooling and cooled pulp of 1.0 - 4.5°C.

EFFECT: reduced flow of air and amount of exhaust gases from the reactor during air cooling of the pulp in frothy conditions, as well as high efficiency of extracting P₂O₅ from the phosphate raw material.

3 cl, 1 tbl, 20 ex