Reductive dissolution of iron (III) from ilmenite ore (FeTiO3) by iron reducing bacteria

Abstract

Extracting titanium from ilmenite ore (FeTiO3) by using the conventional methods require usage of hash chemicals and excessive heating, which are not environmentally friendly. Iron oxides are the most common impurities contained in ilmenite ores. Separating iron impurities from ilmenite ore remains as a challenging part in titanium extraction proses. In this study, we explored the application of iron-reducing bacterium, Shewanella oneidensis MR-1 to leach out iron from ilmenite ore. S. oneidensis MR-1 is known for its capability to reduce various metal oxides during anaerobic respiration. Reduction of iron oxides contained in ilmenite ore by respiration activity of S. oneidensis MR-1 transform insoluble iron(III) to soluble iron(II), which can leach out from the ilmenite ore. Different concentrations of ilmenite were incubated with S. oneidensis MR-1 under anaerobic conditions for 30 days. Reductive dissolutions of iron(III) from ilmenite ore were determined by monitoring iron(II) accumulation in the growth media every 3-4 days. Transformations of ilmenite ore after 23 days of S. oneidensis MR-1 treatment were further analysis by X-Ray diffraction (XRD) analysis. Incubation of S. oneidensis MR-1 with 0.10 g/ml of ilmenite ore showed the highest iron(III) reductive dissolution activity, with 1.4mM of iron(II) was leached out from ilmenite ore after 23 days. The XRD analyses indicated chemical composition and structural changes in the ilmenite incubated with S. oneidensis MR-1. The findings of this study show that reductive dissolution of iron(III) by S. oneidensis MR-1 is a promising environmentally friendly and inexpensive bioleaching strategy in removing iron impurities from ilmenite.