A review of pretreatment of diasporic bauxite ores by flotation separation.

The Bayer process is a conventional method for refining bauxite in the production of alumina. The Al/Si ratio in bauxite before feeding to the process must be enriched to more than eight by reducing impurities (mainly aluminosilicates). Therefore, diasporic bauxite ores (Al/Si < 6) have to be upgraded by pretreatment methods to meet the required quality for the Bayer process. Flotation separation (direct or reverse) followed by flocculation as an efficient pretreatment method is the main beneficiation technique for upgrading diaspore. Diaspore pretreatment by flotation favors several conditions and possesses certain limitations. This study has systematically explored various effective flotation factors (particle size, surface electrical charge, collectors, depressants, dispersants, flocculation and aggregation) and limitations in the pretreatment of diaspore and has compiled optimum results for its beneficiation. The summary offers various approaches for the selective flotation of diasporic ores via different conditions and suggests perspectives for further investigation. [ABSTRACT FROM AUTHOR]