METHOD OF PRODUCING NON-CHLORINE NPK COMPOUND FERTILISERS Russian patent published in 2011 - IPC C05B7/00 C05D1/00 C05G1/00 

FIELD: chemistry.

SUBSTANCE: method involves neutralisation of an acidic phosphorus-containing solution with an alkaline potassium-containing reagent at the first step and then adding sulphuric acid and neutralisation with ammonia at the second step, granulation and drying the end product. Nitric acid and ammonium nitrate are added when neutralising the acidic phosphorus-containing solution at the first step. The alkaline potassium-containing reagent and ammonium nitrate are added to the acidic phosphorus-containing solution while maintaining the required ratio of nutrient components in the end product. Nitric acid is added in an amount which provides pH 2-5 at the first step. The pH value at the second neutralisation step is kept at 4-6. The acidic phosphorus-containing solution used is phosphoric acid or a nitric-phosphate solution which is a product of decomposition of phosphate material with nitric acid with subsequent extraction of potassium in form of a tetrahydrate of calcium nitrate.

EFFECT: method enables to vary the ratio of nutrient substances in the product in a sufficiently wide range and increase strength of granules of the end product and improve its application properties.

4 cl, 4 ex