FRAMGANGSMAATE VED FRAMSTILLING AV FOSFORSYRE OG/ELLER FOSFATER FRA KLORHOLDIGE RAAFOSFATER

Process comprises initial leaching with mineral acid followed by further processing of the resulting mixt. During or after the leaching step at least one strong inorganic oxidising agent is added in an amt. sufficient to completely oxidise the organic and sulphide components of the phosphate, and to completely oxidise the chlorine component to Cl2, the Cl2 thus formed being removed by the ventilation system of the process. Process is simple and economical and enables high-chlorine raw materials to be used which with conventional processes gives rise to corrosion problems. In an example Kola phosphate contg. 0.4% Cl is digested with HNO3 while air is passed through the appts. In the absence of added oxidising agent, the chloride content of the reaction mixture is 0.11% and the waste gases contain 0.5 g HNO3/kg P. When NaClO3 is added, the chloride content of the mixture is 0.012% and the waste gases contain 3.1g HNO3/kg P.