MANUFACTURE OF ABRASION-RESISTANT FREELY-FLOWING SODIUM PERBORATE

摘要

1407335 Sodium perborate KALI-CHEMIE AG 25 Jan 1973 [31 Jan 1972 (2)] 3875/73 Heading C1A [Also in Division G3] In a process for the manufacture of abrasionresistent freely-flowing sodium perborate with a bulk density of 0À75 to 0À85 kg./litre, a sodium metaborate solution is reacted with hydrogen peroxide in an aqueous suspension of sodium perborate thereby to form a crystal suspension of sodium perborate and the solution and the hydrogen peroxide are continuously fed to a reaction vessel at such rates as to maintain in the reaction vessel a molar ratio of NaBO 2 : H 2 O 2 of 1 : 0À35 to 1 : 0À1 in the mother liquor, the crystal suspension being constantly removed from the reaction vessel in an amount corresponding stoichiometrically to the quantity of NaBO 2 supplied, and the crystals being thereafter separated from the mother liquor and dried. During crystallization either the density or the refractive index and sodium metaborate solution or hydrogen peroxide is automatically added in measured quantity through a valve which is regulated in dependence on the measured density or refraction index values so as to maintain the specified molar ratio.