GB954212A - Production of calcium dichloroisocyanurate - Google Patents

Abstract

A hydrate of calcium di(dichloroisocyanurate) is produced by mixing in an aqueous medium either (a) dichloroisocyanuric acid and calcium oxide, hydroxide, or carbonate, or (b) chlorine and tricalcium diisocyanurate, the amount of aqueous medium being such that there is formed a slurry of the solid reactant or reactants in the medium, and the rate of addition to and admixture of the reactants is such as to provide and maintain a pH value of 4.5 to 7.5 in the reaction mixture. Where the reaction temperature is 10 DEG to below 35 DEG C., the hexahydrate is formed, while the tetrahydrate is formed at 37 DEG to 65 DEG C., and a mixture of the two hydrates at 35 DEG to 37 DEG C. The hydrate may be dehydrated to the anhydrous salt by drying, e.g. at 110 DEG C. In (a) at least 15, e.g. 20-50, molecular proportions of water per mol. dichloroisocyanuric acid may be used as such or in admixture with either or both reactants, e.g. 50 to 85% dichloroisocyanuric acid or CaO, Ca(OH)2, or CaCO3 and the remainder water. In (b) an aqueous slurry of 5 to 45 parts tricalcium diisocyanurate in a 100 parts H2O is reacted with gaseous or liquid Cl2 introduced below the surface with agitation. The reaction vessel may be initially charged with water, a solution of CaCl2, or a solution of the product which may be the mother liquor from a previous reaction. In a continuous process, aqueous slurry is removed at such a rate as to maintain the volume constant. After separation of the chloroisocyanurate, the mother liquor may be concentrated at 45 DEG to 65 DEG C. under reduced pressure and cooled to 5 DEG C. to recover further salt. The tricalcium diisocyanurate may be prepared by mixing calcium hydroxide and isocyanuric acid or monocalcium diisocyanurate at 20 DEG to 30 DEG C. in an aqueous medium. The product can be used directly as a water-wet solid.