COMPLEX FERTILISER MANUFACTURE TECHNIQUE Russian patent published in 2010 - IPC C05B11/06 

FIELD: agriculture.

SUBSTANCE: method substance consists in decomposition of apatite concentrate with nitric acid, extraction of some calcium nitrate from nitrate-phosphate extract by means of crystallisation, mixing of phosphorous-containing semi-finished product with previously treated low-grade phosphor raw materials and processing of mixture into a complex fertiliser. Preliminary treatment of low-grade phosphate raw material is executed with nitric acid with further separation of insoluble residue, and liquid products of preliminary treatment are mixed with nitrate-phosphate extract after calcium nitrate portion has been extracted from it. Low-grade phosphate raw materials applied are represented by crushed phosphorite containing 24.6 wt % of P₂O₅ (Karatau phosphorite). Ratio of apatite concentrate and low-grade phosphate raw materials in terms of P₂O₅ is maintained within the limits of (2 ÷ 7) : 1.

EFFECT: method makes it possible to improve strength of produced fertiliser granules.

3 cl, 1 tbl, 4 ex