Gallium and vanadium extraction from red mud of Turkish alumina refinery plant: Hydrogarnet process

In this paper the treatment of red mud by autoclave leaching for its conversion into ferrous hydrogarnet product and extraction of valuable components (i.e. Na2O, Al2O2, Ga and V2O5) was investigated. Leaching of red mud using high modulus alkaline solution (Na2O 240 g/L; alpha(kappa) = 30) in the presence of lime at 240-260 degrees C was found to allow the recovery of the contained values (98.5% Na2O, 65.3% Al2O2, 55.5% Ga and 65.8% V2O5) and the fixing silica in the form of hydrogarnet mud (3CaO center dot Fe2O3 center dot 2SiO(2)center dot 2H(2)O) with a low alkali content (0.35% Na2O). An effective treatment scheme for the leach solution based on precipitation and two-stage carbonization processes was developed and demonstrated. This allowed the generation of alkaline solutions suitable for recycling back to leaching stage and recovery of a concentrate (30% Al2O2) that is rich in Ga (0.32%) and V2O5 (3.7%). The chemical and phase composition of the solid products obtained from each stage of processing were determined by XRF and XRD analyses. This study has demonstrated that Bayer-hydrogarnet process can be suitably exploited for processing of red mud. (C) 2015 Elsevier B.V. All rights reserved.