Refinement of industrial kaolin by microbial removal of iron-bearing impurities

摘要: article i nfo The commercial value of kaolin raw materials is greatly affected by the presence and content iron-bearing impurities, which can have a detrimental effect on whiteness refractoriness manufactured products. Because high cost environmental impact techniques currently used to remove these some effort now targeted toward development alternative methods, such as biological processes. This paper reports series anaerobic microcosm experiments conducted evaluate suitability iron- respiring bacteria (IRB) Shewanella species (S. alga BrY, S. oneidensis MR-1, putrefaciens CN32, CIP 8040), in bioleaching impurities from kaolin. All tested bacterial strains were able reduce leach ferric iron present kaolin, thereby substantially improving its color properties. Among bacteria, CIP8040 produced greatest improvements, with increases ISO brightness 74% 79% 54% 66%, respectively, 5 days at 30°C.Neithersecondarymineralnorcrystal-chemicalalterationofthekaolinitewasobservedbyX-raydiffraction infrared spectroscopy. Observations biotreated kaolins scanning electron microscopy showed that original hexagonal shape clay particles became less regular. Further research should focus optimising rate extent process before application larger pilot or industrial scale. In particular, further studies economical benefits