METHOD OF PROCESSING VYATKA-KAMA PHOSPHORITE Russian patent published in 2001 - IPC

FIELD: manufacture of complex mineral fertilizers from phosphorites 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 2-4 h, and reaction mixture is blown off with oxygen-containing gas, preferably air, separated from alkaline solution by filtration, is 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. EFFECT: simplified processing of Vaytka-Kama phosphorites with insignificant liberation of nitrogen oxides in stage of treatment with nitric acid. 5 cl, 4 ex, 1 tbl