GB665456A - Improvements in or relating to water treating compositions - Google Patents

Abstract

A composition for treating water comprises a substantially homogenous mixture of (a) 80-96 per cent by weight of a water-soluble molecularly-dehydrated alkali metal phosphate having a ratio of alkali metal oxide to P2O5 of from 1.0 to 1.3, (b) 19.98-2 per cent by weight of an alkali metal carbonate, bicarbonate or percarbonate or of a mixture thereof, and (c) 0.02-2 per cent by weight of an olefinic hydrocarbon containing from 6 to 12 carbon atoms for each double bond. The percentage of phosphate in the composition is preferably not less than 88 per cent and the percentage of carbonate or the like is preferably from 10 to 3.98 per cent. Examples of olefinic hydrocarbons are octene and "propylene polymer," the latter being an olefinic hydrocarbon mixture containing a major proportion of dodecene. In one example 1 per cent by weight of propylene polymer is added to a mixture of a commercial sodium hexametaphosphate product and 6 per cent of sodium carbonate. In another example the hexametaphosphate is replaced by sodium septaphosphate (Na9P7O22). When the composition contains an alkali metal carbonate, bicarbonate or a mixture thereof the ingredients of the composition must be so proportioned as to yield a pH in 1 per cent aqueous solution of 6.7 to 8.0, preferably 7.8. Additional alkalinity-adjusting agents such as caustic soda, sodium sulphate, bisulphate or bisulphite, sodium metasilicate, trisodium orthophosphates, sodium pyrophosphates such as tetra-sodium pyrophosphate and sodium acid pyrophosphate, sodium polyphosphates having a Na2O/P2O5 molecular ratio above 1.3, and mixtures of these, and also the corresponding potassium salts may be added to the composition. The particle size of the main phosphate part of the composition should be not coarser than 50 (preferably 100) mesh.