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CSIR-Institute of Minerals & Materials Technology, Bhubaneswar-751 013, Odisha, India E-mail : drpanda_cr@yahoo.com Fax : 91-0674-2567637 Manuscript received 11 October 2015, revised 18 January 2016, accepted 16 February 2016 The present study examines the rate of extraction of metals mainly aluminium and iron from coal fly ash collected from the captive power plant of Vedanta Aluminum Limited, Jharsuguda, Odisha by direct acid leaching method. The effect of different mineral acids, acid concentrations and solid : liquid ratios on rate of extraction of aluminium and iron have also been studied. The results presented in this paper shows sulphuric acid is the bes t leachant in comparison to other mineral acids. Aluminium extraction efficiency of 68.68% was achieved with sulphuric acid as leachant at 220 ºC and at 1 : 3 solid to liquid ratios. It is also evident that extraction efficiency of aluminium and iron increases significantly with increasing concentration of acids and with solid : liquid ratio variation. The pre-leached and postleached fly ash samples were analyzed for observing the morphological and mineralogical changes. Morphological and X-ray diffraction (XRD) analysis of post-leached residues indicated that the mullite inside fly ash was thermally decomposed during leaching with sulphuric acid due to the transformation of alumina and mullite into aluminium sulphate. |
