COMPLEX FERTILIZER PRODUCTION PROCESS Russian patent published in 2003 - IPC

FIELD: fertilizer production. SUBSTANCE: invention relates to processes of production of complex fertilizers, in particular nitrogen-phosphorus-potassium fertilizers containing nitrogen and potassium in forms soluble in water and citric acid. Process involves neutralizing phosphoric acid with potassium-containing alkali reagent at pH 3.5-7.2, mixing resulting pulp with sulfuric acid and neutralizing the latter with ammonia at pH 3.8-5.3, granulating and drying of end product, provided that phosphoric acid contains 1.8-6.5% magnesium oxide and, prior to mixing with sulfuric acid, phosphorus-potassium pulp is treated with phosphoric acid or with ammonia in amounts 8.2-18.7% and 15.2-35.7%, respectively, of the total amount of these reagents taking part in the process. Magnesium-containing fertilizer thus obtained contains potassium citrate within the limits 0-100% and nitrogen 0-30%. EFFECT: prolonged fertilizing effect and increased usage factor for nitrogen and potassium components in soil. 1 tbl, 6 ex