Enrichment and separation of iron minerals in gibbsitic bauxite residue based on reductive Bayer digestion
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metals, Central South University, Changsha 410083, China;
3. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China)
2. National Engineering Laboratory for High Efficiency Recovery of Refractory Nonferrous Metals, Central South University, Changsha 410083, China;
3. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China)
Abstract: The mineralogical characteristics of three kinds of gibbsitic high-iron bauxite and the effects of various digestion conditions on the enrichment and separation of iron minerals were investigated. The results show that adding an appropriate organic reductant such as glycerol can promote the digestion of concomitant diaspore, boehmite and alumogoethite as well as the conversion of goethite to hematite in the reductive Bayer digestion. Processing Bauxite A with A/S of 25.41 can directly produce qualified iron concentrates (TFe>56%) by the reductive Bayer digestion, and thus realize the zero red mud discharge. For Bauxite B and Bauxite C with A/S of 7.82 and 3.35, the iron recoveries of 65.13% and 79.13% can be achieved with the corresponding TFe of 52.05% and 50.16% in the iron concentrates by gravity separation, respectively, resulting in the red mud discharge reduction of ~50% or above.
Key words: gibbsitic bauxite; red mud; iron minerals; enrichment; mineralogical characteristics