Process for the preparation of a polishing alumina from aluminium hydroxides

摘要

The invention relates to a process for the preparation of a polishing alumina from aluminium hydroxides, especially aluminium trihydroxides. The object of the invention is an energy-saving process for the preparation of polishing alumina for the processing of plastics-coated surfaces when poor qualities are obtained in small amounts. The starting material used is bayerite having a residual moisture content of < 5% and a particle size of between 45 and 125 mu m, which is milled in a continuously operating two-tube vibratory mill during residence times of 30 minutes per milling tube with a degree of comminution of 8 to 10. The temperature in the first milling tube is between 80 and 110 DEG C and that in the second milling tube is between 120 and 180 DEG C. The volume ratio of grinding media to mill base is 10 : 1 to 13 : 1 and the size ratio of grinding media to mill base is 200 : 1 to 500 : 1.