MR Hosseini, SM Sadeghieh, MR Azizinia, SH Tabatabaei Separation Science and Technology 55 (11), 2061-2071. Description : Separation of quartz and kaolinite was examined in the absence and presence of the cells and extracellular polymeric substances (EPS) of Bacillus licheniformis in alkaline conditions. The adsorption density of EPS and bacterial cells on kaolinite increased by raising the pH value from 9 to 12, whereas for quartz the trend was in reverse. The highest difference between the settling rates of two minerals happened at pH = 12, 11, and 10 using no bio-reagents, bacterial cells, and EPS, respectively. The mineral separation tests indicated that using the bacterial cells, 98.3% of kaolinite was recovered, and quartz content was reduced by 8%.