METHOD OF PREPARING FERTILIZERS Russian patent published in 2001 - IPC

FIELD: preparation of mineral fertilizers containing phosphorus, nitrogen, and sulfur. SUBSTANCE: method comprises step-by-step neutralization of mixture of phosphoric and sulfuric acids with ammonia, granulation and drying of product. Neutralization is carried out first at to pH of 5.8-6.7 at rarefaction of 10-30 mm water column, afterneutralization of pulp prepared after first stage of neutralization of pulp to desired pH value. Fertilizers having additional amount of potassium are optionally prepared. Ratio of H₂SO₄ : H₃PO₄ acids in mixture is maintained at 1:(0.0067-3.0), and potassium-containing additive is added either to pulp prepared from first-stage neutralization or after afterneutralization in dry form or aqueous suspension form. When potassium-containing additive is used in aqueous suspension form, clay is added thereto in amount of 0-2% of weight of suspension. Process is stable, is readily automated and makes it possible to prepare nitrogen-phosphorus or nitrogen-phosphorus- potassium fertilizers having high sulfur content. EFFECT: more efficient preparation method. 3 cl