METHOD FOR PROCESSING PHOSPHOGYPSUM FOR COMPLEX FERTILIZER CONTAINING NITROGEN, CALCIUM AND SULFUR Russian patent published in 2019 - IPC C05B11/00 C05C9/00 C05D3/02 C05G1/00 

FIELD: agriculture.

SUBSTANCE: method of processing phosphogypsum for complex fertilizer involves conversion of phosphogypsum with subsequent separation of precipitate from the solution, while before conversion of phosphogypsum its suspension with humidity of 56–59 % is obtained, resulting suspension of phosphogypsum is divided into two parts, conversion of the first part of the phosphogypsum suspension is carried out at temperature of 70–100 °C by entering into it with continuous stirring of sodium carbonate with formation of suspension consisting of calcium carbonate and sodium sulfate solution, and in the second part of the phosphogypsum suspension, carbamide is introduced with continuous stirring at a certain ratio of components, while maintaining the temperature of suspension 50–55 °C, resulting in suspension of chemical compound CaSO₄⋅4CO(NH₂)₂, calcium carbonate, obtained after conversion of the first part of phosphogypsum suspension, is mixed with suspension of chemical compound CaSO₄⋅4CO(NH₂)₂, moreover, calcium carbonate mixture with chemical compound CaSO₄⋅4CO(NH₂)₂ is carried out at a certain ratio of components, suspension of complex fertilizer obtained as a result of such mixing is directed to drying and granulation.

EFFECT: invention allows to expand arsenal of methods of processing phosphogypsum.

1 cl, 4 ex