Possibilities of fly ash activation in alumina recovery process

This paper summarises various possibilities of high-temperature fly ash (HTA) and fluidised-bed filter ash (FFA) activation in metal and oxides recovery processes (esp. alumina recovery). The study deals with chemical and phase composition ash modification to improve leachability of aluminium compou...

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Bibliographic Details
Published in:IOP conference series. Materials Science and Engineering 2019-07, Vol.583 (1), p.12003
Main Authors: Marko, M, Opravil, T, Masilko, J, Porizka, J
Format: Article
Language:English
Subjects:
Acids
Aluminum compounds
Aluminum oxide
Calcium aluminate
Calcium carbonate
Calcium chloride
Calcium oxide
Chemical composition
Fly ash
Gypsum
High temperature
Leaching
Lime
Phase composition
Power plants
Sintering
Sulfuric acid
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Summary:This paper summarises various possibilities of high-temperature fly ash (HTA) and fluidised-bed filter ash (FFA) activation in metal and oxides recovery processes (esp. alumina recovery). The study deals with chemical and phase composition ash modification to improve leachability of aluminium compounds into sulphuric acid solution. Samples of HTA and FFA produced by power plant industry in the Czech Republic were subjected to diverse types of modification, such as sulphuric acid concentration, ash/acid ratio and sintering reactions using several types of solid agents. Sintering reaction were based on forming acid soluble calcium aluminates via donating the system with calcium oxide, - carbonate and - chloride. Phase and chemical composition were characterised by means of XRD and XRF analysis and the concentration of Al in acid solutions via ICP-OES. Appropriate modification of input material by high-temperature sintering reaction using calcium chloride combined with extraction into 10 wt. % sulphuric acid leads to dissolution up to 99% of aluminium from FFA and up to 94% form HTA. At least, irreplaceable dopant for cement production - gypsum, is formed as a by-product of leaching.
ISSN:1757-8981
1757-899X
DOI:10.1088/1757-899X/583/1/012003