PRODUCTION OF MADDRELL SALT

摘要

PRODUCTION OF MADDRELL SALT Pure Maddrell salt is produced by heating sodium phosphate to temperatures of 250 to 420.degree.C. The sodium phosphate used as starting material is sodium trimetaphosphate or a mixture of sodium trimetaphosphate with Maddrell salt, monosodium orthophosphate or disodium pyrophosphate, the mixture containing Na and P in a molar ratio of 1 : 1. Prior to heating the starting material, it is admixed with 0.5 to 5 weight% of orthophosphoric acid, polyphosphoric acid, phosphorus pentoxide or at least one salt of a volatile base forming polyphosphoric acid at the temperatures specified, The resulting mixture is calcined over the period necessary to transform the starting material to Maddrell salt.