METHOD OF PREPARING VAYTKA-KAMA PHOSPHORITE Russian patent published in 2001 - IPC

FIELD: manufacture of complex mineral fertilizers using nitric acid technology. SUBSTANCE: prior to being treated with nitric acid, Vyatka-Kama phosphorite meal is treated, while stirring, with alkaline solution, preferably with 3% sodium hydroxide solution at 95-100 C for 22-4 h, separated from alkaline solution by filtration, then treated with unconcentrated nitric acid, insoluble residue is separated by filtration, the resulting solution is converted to fertilizer. Insoluble residue is washed with spent alkaline solution; the resulting solution containing sodium nitrate and humate is added to fertilizer to increase nutrient value thereof. Method makes it possible to convert Vaytka-Kama phosphorites without calcination of raw materials to improve specific efficiency of filtration during separation of insoluble residue. EFFECT: more efficient processing method. 4 cl, 1 tbl