Abstract: The invention relates to a method for utilizing silicon tetrachloride formed as a by-product of the chlorination of aluminium- and silicon-containing minerals. More particularly, the invention relates to a process for the preparation of aluminium trichloride and silicon dioxide by chlorination of alumina with silicon tetrachloride. According to the invention alumina or a material essentially consisting of alumina is reacted with silicon tetrachloride as a single chlorinating agent at a temperature exceeding 400.degree. C., unreacted silicon tetrachloride is separated from the aluminium trichloride formed and is recycled into the chlorination step, silicon dioxide is isolated from the solid residue essentially consisting of the unreacted alumina and silicon dioxide, unreacted alumina is recycled into the chlorination step and aluminium trichlorine obtained is continuously eliminated.