METHOD FOR THE PRODUCTION OF ALUMINA

摘要

In the production of alumina, a comminuted charge of aluminium-containing raw material and carbonate raw material in a soda-containing solution is sintered prior to the separation and calcining of aluminium hydroxide. The present invention produces the comminuted charge by comminuting alumina-containing raw material in a soda-containing solution so that the fraction of comminuted material of size greater than 0.08 mm amounts to over 12 percent by weight; mixing the comminuted alumina-containing material with carbonate-containing raw material and a soda-containing solution to ensure a molecular ratio of alkali metal oxide to alumina of at least 1 to 1 and a molecular ratio of calcium oxide to silica of 2 +/- 0.03 to 1; and comminuting the charge to obtain a fraction of size greater than 0.08 mm in an amount of 2 to 15 percent by weight.