Granulated blast furnace slag (GGBFS) is a potential resource of rare earth elements (REEs), and due to the complex mineralogy, extraction by conventional hydrometallurgical process makes it an acid-consuming method. Bioleaching thus investigated using chemo-organotrophic bacterium Gluconobacter oxydans (DSMZ 46616) for REE from GGBFS containing 157 ppm Ce, 90 La, 71 Nd 40 Er, hosted in Ca-Al-S...