Process for reducing the iron

摘要

The invention relates to an improved process for reducing the iron content of iron-, silicon- and aluminium-containing raw materials and for producing ferric oxide, optionally along with an alumina concentrate. According to the invention the iron content of mineral raw materials, e.g. bauxites, clay minerals, colliary rocks, red muds, etc. is eliminated by passing through one or more beds prepared from the unground but preferably prebroaken and sized raw material an aqueous hydrochloric acid solution, the concentration of which exceeds 100 g./lit., at a temperature below 90 DEG C., preferably at room temperature, optionally in the presence of a flocculating agent. By pyrolytic decomposition of the ferric chloride prepared ferric oxide can be produced. The bed residue of reduced iron content can be utilized in the Bayer process for producing alum earth, as a starting substance of ceramic industry or, after treating with sulfuric acid, dissolving in hydrochloric acid or water, elimination of silica, pyrolytic decomposition of the aluminium sulfate obtained, as an alumina concentrate.