METHOD OF PRODUCTION OF THE FOOD DIAMMONIUM PHOSPHATE FROM THE PURIFIED EXTRACTION PHOSPHORIC ACID Russian patent published in 2006 - IPC C01B25/28 C05B7/00 

FIELD: food industry; pharmaceutical industry; chemical industry; methods of production of the food diammonium phosphate from the purified extraction phosphoric acid.

SUBSTANCE: the invention is pertaining to the method of production of the pure diammonium phosphate from the purified extraction phosphoric acid (EPA), which may be used in the food, pharmaceutical and chemical industries. The method provides, that the EPA prepurified by the organic extractant -tributylphosphate at the stage of concentrating is subjected to the additional purification by means of the solution containing cations_{NH4 ⁺ from the residual sulfates as well as from compounds of iron and aluminum The additional purification is conducted at the ratio of NH3 to the sum of the all impurities in the acid equal to 1.5 kg/kg. So purified EPA is transferred onto the phase of production of the diammonium phosphate (DAF), where it is ammoniated by aeriform ammonia up to the ratio ofNH3 : H3PO4 near to 1.8. The produced fine pulp is subjected to centrifuging and the mother liquor, which has the alkalescent reaction and contains the dissolved impurities, is completely withdrawn from the stage of production of the DAF for utilization. The crystalline product - the food DAF after separation from the mother liquor without the additional drying is packaged up and sent to the customers. The utilization of the mother liquor is realized at the stage of purification of the EPA, using NH4 ⁺ as the source of the cations the above described purification, and also for production of fertilizers. One of the versions of the utilization is the usage of the mother liquor for the flashing of the extract on the stage of purification of the EFA by the tributyl phosphate. As a result of this operation the DAF solution gets into the raffinate, which represents the liquid nitrogenous phosphatic fertilizer. The method allows to reduce the concentration of fluorine, iron, aluminum, lead and an arsenic compounds below the standards provided by the State Standard Regulations (GOST) on the food DAF, to simplify the process due to elimination of operations of the additional concentration and drying, to solve the problem of the usage of the mother liquor after centrifuging and to produce an additional product - the liquid nitrogenous phosphatic fertilizer.}

EFFECT: the invention ensures: reduction of the concentration of fluorine, iron, aluminum, lead and an arsenic compounds below the GOST standards on the food DAF; simplification of the production process due to elimination of the additional operations on concentration and drying; solution of the problem of the mother liquor usage after centrifuging; production of the additional product - the liquid nitrogenous phosphatic fertilizer.

2 cl, 2 ex, 1 tbl