GB1109617A - Manufacture of ammonium sulphate - Google Patents

Abstract

Powdery ammonium sulphate is continuously produced from ammonia and sulphuric acid by a process comprising (i) adding to a recycling bed of solid ammonium sulphate of moisture content less than 8% by weight an aqueous solution or slurry of ammonium sulphate of water content 13 to 48% by weight, and ammonia and sulphuric acid, of concentration greater than 60% by weight H2SO4, in such proportions and at such rates that substantially ammonium sulphate is formed, that the temperature of the bed of solid ammonium sulphate is maintained below 110 DEG C., and that the heat of the reaction drives off sufficient water to reduce the water content of the added reactants and the bed to below 5% by weight, (ii) withdrawing from the bed an amount of solid product substantially equivalent to that produced by addition of the reactants, (iii) recycling the remainder of the solid ammonium sulphate. The following preferable conditions are specified: the bed should contain at least 2 1/2 % by weight of water, and its temperature should be maintained below 65 DEG C. The ammonium sulphate solution or slurry should be made by reaction of substantially stoichiometric proportions of gaseous ammonia and sulphuric acid of H2SO4 content 30 to 50% by weight, should contain 15 to 25% by weight of water and be within 10 DEG C. of its boiling point on addition to the bed. Reactant ammonia should be gaseous and reactant sulphuric acid should contain more than 80% H2SO4 by weight. Recycling should be accompanied by agitation, which is conveniently achieved in a trough mixer of type described in Specification 1,001,031.