Simultaneous removal of sulfur and iron by the seed precipitation of digestion solution for high-sulfur bauxite

Sulfur in bauxite ore results in a series of notable negative effects in Bayer process. It is necessary to remove sulfur for the utilization of high-sulfur bauxite resources. A novel process involving seed precipitation of digestion solution was adopted to simultaneously remove sulfur and iron from the sodium aluminate solution for the high-sulfur bauxite. Seed was prepared from the digestion solution of pyrite in a water bath. X-ray diffraction, a scanning electron microscope and chemical analysis were used to characterize the prepared seed. The utilization of the seed precipitation to remove sulfur and iron for the sulfur-containing sodium aluminate solution was studied. The various parameters included seed dosage, agitation speed and temperature. The results indicated that seed dosage and temperature had a remarkable effect on the sulfur and iron removal. Under the optimum condition, the removal percentages of sulfur and iron from the digestion solution can achieve to 76% and 87%, respectively, and the loss of alumina is lower than 2%. The research shows that the sulfur and iron seed prepared from pyrite can be used effectively for the sulfur and iron removal. A cyclic flowsheet for the simultaneous removal of sulfur and iron for high-sulfur bauxite is proposed.