ZPUSOB VYROBY ALFA OXIDU HLINITEHO S NIZKYM OBSAHEM ALKALII PRO KERAMICKE UCELY

摘要

Process for the preparation of alkali-poor alpha -alumina for ceramic purposes. Technical grade aluminum hydroxide is activated and calcinated in the presence of a mineralizing mixture comprising halides and boron compounds. The process further comprises activating aluminum hydroxide at a temperature of 500-600 degrees C., washing the activated product with alkali-free water containing calcium ions and having a conductivity not exceeding 70 mu S/cm until the alkali content expressed in Na2O becomes lower than 0.15% by weight, adding 0.4-0.7% by weight of a mineralizing mixture to the washed product, and calcinating the same at a temperature of 1200-1350 degrees C.