Process for the reduction of lye impurities in the Bayer process.

摘要

In processes for reducing the dissolved inorganic and organic impurities in aqueous bases in the Bayer process for the preparation of aluminium hydroxide, additives are used which require complicated process procedures and an increased consumption of base, which causes increased production costs and does not always ensure good product quality. These disadvantages can be prevented by subjecting the contaminated base Pv to electrodialysis using at least one anion- and/or at least one cation-permselective membrane and at least one bipolar, water-dissociating membrane with the formation of an alkali metal base component Pr which is added to the cycle base of the Bayer process and a contaminated component V which is removed from the process and discarded.