Process for the simultaneous production of aluminium oxide and iron(III) oxide side by side

摘要

The invention relates to a process for the simultaneous production of aluminium oxide and iron(III) oxide side by side with advantageous degrees of purity for further processing of at least 80 % in aluminium oxide and 90 to 99 % in iron(III) oxide from mineral raw materials having high iron and/or silicon contents, by treatment of which with hydrochloric acid having concentrations of at least 200 g/l at temperatures of at least 60 DEG C, intermittent or continuous removal of the iron(III) chloride by means of an anion exchanger and optionally elution of the iron(III) chloride from this and evaporation of the iron(III) chloride solutions obtained and pyrolytic cleavage of the iron(III) chloride with feeding-back of the hydrochloric acid in a closed circuit to prior stages, in which, after treatment with hydrochloric acid having concentrations of 200 g/l to 420 g/l at temperatures from 60 to 130 DEG C, the removal of the iron(III) chloride is carried out immediately from the suspension obtained by bringing this into contact with the anion exchanger and the iron-free residue obtained is sulphated, dissolved and filtered and optionally further purified in a manner known per se and the aluminium sulphate solutions obtained are evaporated in a manner known per se and the aluminium sulphate obtained is cleaved pyrolytically, the sulphuric acid obtained in this process and in the sulphation, optionally as sulphur trioxide, and hydrochloric acid being fed back in a closed circuit to prior stages.