METHOD OF PREPARING GRANULAR COMPLEX FERTILIZERS HAVING MICROELEMENTS Russian patent published in 1999 - IPC

FIELD: agriculture, more particularly preparation of granular complex fertilizer based on fertilizer mixtures for various types of soils. SUBSTANCE: method comprises dry mixing of granular components containing nitrogen, phosphorus, potassium and microelements. Microelements are mixed with calcium-and sulfur-containing substances, the resulting mixture is granulated at moisture content of 10-20% and temperature of 50-75 C to obtain granules with particle size of 1-4 mm, and granules in amount of 10-25 wt % based on total fertilizer weight are then mixed with granular nitrogen, phosphorus-and potassium-containing constituents. Calcium-containing substances include calcium and/or ammonium sulfate and phosphoric acid production waste, e.g. phosphogypsum. Microelements include boric acid, zinc, manganese, copper sulfates and other essential elements for certain types of fertilizer. The resulting complex fertilizers with microelements have identical composition with respect to entire weight. EFFECT: more efficient preparation method. 2 cl, 3 ex