Method for processing alumina-containing raw material and method for breaking down alumina-containing raw material during processing

摘要

The invention relates to chemistry and metallurgy and is intended for the processing and breakdown of alumina-containing raw material. A processing method is carried out as a cyclic process that includes: a breakdown stage, in which raw material is decomposed using a reagent solution containing ammonium bisulphate and sulphuric acid and the resultant slurry is separated, producing undecomposed solid residues, which are rinsed with water, and an alum mother solution, wherein the alum mother solution and the rinse waters are collected separately; a purification stage, in which the rinse waters are purified of iron then combined with the alum mother solution and cooled, and crystals of ammonium alum are isolated, wherein the sulphuric acid used for the reagent solution in the breakdown stage is separated off; a precipitation stage, in which aluminium hydroxide is precipitated from the purified alum solution with ammonia; a separation stage for separating off aluminium hydroxide; a stage for obtaining solid ammonium sulphate and a stage for the thermal decomposition thereof into ammonium bisulphate and ammonia, which can be used in the breakdown stage, during the preparation of the reagent solution, and in the precipitation stage, respectively. The invention makes it possible to process any alumina-containing raw material at low temperatures, to reduce reagent loss and to reduce the volume of reagents which needs to be replenished during the process.