METHOD OF OBTAINING COMPLEX FERTILISERS Russian patent published in 2010 - IPC C05G1/06 

FIELD: agriculture.

SUBSTANCE: method for producing compound fertilisers include the neutralisation of phosphoric acid and sulfuric acid in three stages, the introduction of potassium chloride, granulation and drying of the product, as a phosphoric acid wet-process phosphoric acid is used that contains 33 - 40% P₂O₅ and 1.2 - 2.0 % of magnesium compounds in terms of MgO. Neutralisation of acids is carried out in three stages. At the first stage the phosphoric acid is mixed with absorbent sinks until the mixture density is 1.36 - 1.44 g/cm³, and is neutralised to obtain a reaction mass with the molar ratio NH₃/H₃PO₄, equal to 0.2-0.5. The second stage is carried out by ammonia neutralisation of the reaction mass and sulfuric acid in a tubular reactor to produce pulp with a molar ratio NH₃/H₃PO₄, equal to 0.8-0.9 or 1.3-1.4. In the third stage ammonisation of pulpis completed in ammonisator - pelletiser to a final molar ratio NH₃/H₃PO₄ equal to 1.0-1.7. Sulfuric acid is administered in an amount of 0.7-2.4 t in terms of the monohydrate of 1 ton of P₂O₅. Nitrogen-containing component is administered in an amount of 2 - 11% by weight of the finished product on the stage of granulation, as a nitrogen-containing components urea, ammonium nitrate in a dry form are used.

EFFECT: method allows you to get the sulfur complex nitrogen-phosphor-potassium fertilisers of various grades with high physical properties at high-performance process.

2 cl, 1 tbl, 5 ex