PROCESS OF PRODUCTION OF MIXED FERTILIZER WITH SULFATE ADDITIVE Russian patent published in 2004 - IPC

FIELD: mineral fertilizers. SUBSTANCE: mixed nitrogen/phosphorus and nitrogen/phosphorus/potassium fertilizer with sulfate additive is produced by decomposing phosphate raw material with nitric acid, after which nitric acid extract is cooled to precipitate calcium nitrate crystals, nitrate- phosphate solution is completed with sulfuric acid followed by neutralization with ammonia to pH no lower than 4, evaporating ammonized pulp, adding (if necessary) potassium chloride, granulation, and drying of final product. According to invention, before addition of sulfuric acid, nitrate-phosphate solution is preliminarily neutralized with ammonia to pH 1-2. Content of sulfur in fertilizer is maintained within a range of 1 to 2.5%. EFFECT: suppressed incrustation of equipment in sulfuric acid introduction unit so eliminating its clogging. 2 cl, 1 tbl