Process for removal of sodium oxalate from sodium aluminate solutions originating from the Bayer-Cycle.

摘要

The sodium oxalate in at least one fraction of the sodium aluminate solution or liquor withdrawn in the Bayer cycle for the production of alumina from bauxite, after the decomposition and concentration stages of the said liquor intended to be recycled as alkaline liquor for attacking the bauxite ore, is removed by precipitation of the dissolved sodium oxalate by means of a destabilising agent of the supersaturated state of the sodium oxalate and then separation of the sodium oxalate thus precipitated. According to the invention, the destabilising agent of the supersaturated state of the sodium oxalate brought into contact for more than 1 hour with the cooled sodium aluminate solution is lime which can optionally contain magnesium oxide and which can be directly introduced into the sodium aluminate solution in the form of quicklime CaOa in the form of a milk of lime.