METHOD OF PROCESSING PHOSPHOGIPSA FOR NITROGEN-PHOSPHOROUS FERTILIZER Russian patent published in 2019 - IPC C05B11/00 C05G1/00 

FIELD: agriculture.

SUBSTANCE: invention relates to agriculture. Method of processing phosphogypsum for nitrogen-phosphorus fertilizer involves conversion of phosphogypsum followed by separation of precipitate from solution, and conversion of phosphogypsum is carried out with solution of sodium carbonate at a temperature of 70–100^os and continuous stirring, resulting in suspension in which solid part is calcium carbonate, and liquid part is sodium sulfate solution, calcium carbonate is separated from sodium sulfate solution and washed, washed calcium carbonate is sent to neutralize phosphoric acid with content of 35–37 wt. % P₂O₅ to obtain suspension containing monocalcium phosphate with humidity of 61–62 %, suspension of phosphogypsum is prepared and mixed with urea and therewith suspension of chemical compound is obtained CaSO₄·4CO(NH₂)₂ with humidity of 39–41 %, at the final stage mixing a suspension of monocalcium phosphate with suspension of chemical compound CaSO4⋅4CO(NH₂)₂ suspension of nitrogen-phosphorus fertilizer with humidity of 44–54 % is obtained and sent for drying and granulation. Invention allows to expand range of methods of processing phosphogypsum with obtaining nitrogen-phosphorus fertilizer in form of granules, 2–4 mm in size, the following composition, wt. %: CaO 16.5–20.0; P₂O₅ 10.5–33.5; N 13.5–24.7; S 3.9–7.0, and having pH value of 5.2–6.5.

EFFECT: invention allows to expand range of methods of processing phosphogypsum with production of nitrogen-phosphorus fertilizer in form of granules.

3 cl