Kumar, Rakesh and Alex, T C and Mishra, C R and Roy, S K and Mehrotra, S P (2007) Towards Sustainable Alumina Production. In: National Seminar on Environmental Concern and Remedies in Alumina Industry, January 27-28, 2007, NML, Jamshedpur.
This paper, an overview • of research pursued at NML towards sustainable alumina production, ',deals with: (a) a chemical beneficiation of red mud to recover all its constituents, and (b) a novel process to reduce the alumina and soda content of red mud using mechanochemical activation (MA) of bauxite. As a part of the study on chemical-beneficiation of red mud, phase stability in the system Fe203-A1203-Na2CO3- C has been investigated using free energy minimization. Using these results, a process involving solid-state carbothermic reduction of red mud in the presence of soda, water leaching for alumina recovery and magnetic separation of leach residue for the sepa-ration of iron and TiO2 rich _fraction has been evaluated. Experimental results are explained using extensive X-ray diffraction and SEM-EDS studies on various solid residues generated in the different stages of the process. Mecha-nical activation of bauxite is investigated: (a) as pre-treatment to the Bayer process; and (b) mechanochemical leaching of bauxite, i.e. simultaneous milling and leaching of bauxite. The superiority of mechanochemical leaching over the existing Bayer 1. process practice and MA as pretreatment has been established. Using the novel process the approach of mechanochemical leaching, reduc-tion in soda content of red mud to less than 1% and alumina content to less than half is possible with additional benefits in terms of moderation in process condition, simplicity of the process and efficient utilization of energy. Merits of the investigated processes have been highlighted vis-à-vis previous studies on red mud utilization and minimization of its enviro-nmental impact.
|Conference or Workshop Item (Paper)
|Alumina; Energy minimization; red mud; aluminium production;
|Metal Extraction and Forming
|Sahu A K
|03 Jul 2012 16:37
|03 Jul 2012 16:37
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