COMPLEX FERTILIZER PRODUCTION PROCESS

mineral fertilizers. SUBSTANCE: invention relates to mineral fertilizers based on extraction phosphoric acid and can be used for production of fertilizers containing phosphorus, potassium, and magnesium. Phosphoric acid is neutralized to pH 4-4.5 in the first stage with alkali metal bases, e.g. potassium carbonate, potassium and sodium hydroxide, soda ash, or their mixtures. Resulting suspension is separated to give liquid phase and precipitate. The former is mixed with acid-soluble calcium-containing compounds in amounts 0.6-5.0 wt parts CaO per 100 wt parts of phosphoric acid to provide pH 0.6-8.0. Liquid phase is additionally neutralized to pH within a range of 6.5-7.5, filtered (precipitate is returned into the first neutralization step), and concentrated to give precipitate, which is then dried. Sum of nutritive chemicals in fertilizer achieves 99.3%. EFFECT: increased nutritive value of fertilizer. 4 cl, 3 tbl, 3 ex