A perspective of stepwise utilisation of Bayer red mud: Step-two Extracting and recovering Ti from Ti-enriched tailing with acid leaching and precipitate flotation

The extraction and recovery of Ti from Ti-enriched tailing with acid leaching and precipitate flotation, as one of the critical steps, was proposed for the stepwise utilization of red mud. The factors influencing acid leaching and precipitate flotation were examined by factorial design. The leaching thermodynamics, kinetics of Ti4+, Al3+ and Fe3+, and the mechanism of selectively Fe3+ removal using [Hbet][Tf2N] as precipitating reagent were discussed. The extracting of Ti4+, Al3+ and Fe3+ in concentrated H2SO4 is controlled by diffusion reactions, depending mainly upon leaching time and temperature. The maximum extracting efficiency of Ti4+ is approximately 92.3%, whereas Al3+ and Fe3+ leaching are respectively 75.8% and 84.2%. [Hbet][Tf2N], as a precipitating reagent, operates through a coordination mechanism in flotation. The pH value is the key factor influencing the flotation recovery of Ti4+, whereas the dosage of precipitating reagent is that for Al3+ recovery. The maximum flotation recovery of Ti4+ is 92.7%, whereas the maximum Al3+ recovery is 93.5%. The total recovery rate for extracting and recovering titanium is 85.5%. (C) 2016 Elsevier B.V. All rights reserved.