Method for producing triple superphosphate fertilizers

Abstract

The subject of the application is a method for producing phosphate fertilizers of the triple superphosphate type by reaction of a phosphate rock substrate and orthophosphoric acid (V), wherein the phosphate rock substrate is a mixture of crushed, natural phosphate rock with a P2O5 content of at least 37% (m / m) and ash resulting from the mono-combustion of sewage sludge with a P2O5 content of at least 27% (m / m), mixed in such proportions that the substitution of phosphorus compounds introduced into the reaction environment by the phosphate rock with phosphorus compounds introduced by the ash from sewage sludge is from 10% to 70% (m / m).The substrate is introduced into orthophosphoric acid (V), with a concentration of 28% to 32% in terms of P2O5, heated to a temperature of not less than 55°C, not higher than 65°C, in portions, with constant stirring, until all the raw material is introduced, wherein the reaction is carried out with an excess ratio of acid to raw material ranging from 1.1:1 to 1.2:1, in open reaction vessels, maintaining the temperature of the reaction environment in the range of 90°C to 100°C, stirring periodically, until the reaction product solidifies in the form of a pulp.