Extraction of alumina from fly ash by pyro-hydro metallurgical routes: A review

Rahul Mandal 1, *, Manaranjan Mohanta 2

1 Department Of Material Science, Maharaja Sriram Chandra BhajaDeo University, Odisha, India
2 Department of Physics, Indira Gandhi National Tribal University, Amarkantak, Madhya Pradesh, India.
 
Review
International Journal of Science and Research Archive, 2024, 11(02), 740–749.
Article DOI: 10.30574/ijsra.2024.11.2.0495
Publication history: 
Received on 11 February 2024; revised on 19 March 2024; accepted on 22 March 2024
 
Abstract: 
Fly ash is a resulting by-product formed due to the burning of pulverized coal on a steam-generating plant. Fly ash mainly contains alumina and silica, hence it can be an excellent secondary source for alumina. Today only 30% of global fly ash can be reused commercially, the remaining was dumped. This causes waste of resources and environmental pollution too. The alumina in the fly ash was in the form mullite phase which is a stable phase so decomposition of this phase is difficult. The mullite phase can be disilicated by calcination, roasting, etc which were pyro-metallurgical routes. Alumina can be extracted as aluminum hydroxide and other unstable forms from fly ash by hydrometallurgical routes. This process requires a huge amount of energy for reaction which is a major drawback of this process. Till now industrial extraction of alumina from fly ash cannot be feasible. Different researchers and scholars did various works to overcome this difficulty. This paper presents a review for extraction of alumina via these routes. It starts with different concepts used in extraction of alumina from fly ash. The middle portion presents the survey of work done by different scholars. The work finally concludes with future possibilties.
 
Keywords: 
Fly ash; Mullite; Kaolite; Zeolite; Extraction; Alumina
 
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