In order to evaluate the quality of kaolinite, the color of its impurities has always been more noticeable. But in the present era, and after expanding the methods for reducing the amount of impurities in color, attention has been paid to the reduction of another of the most important impurities of kaolinite, namely silica. Due to the success of biological methods in the separation of colored impurities, their use to reduce the content of silica also effectively reduce the cost of operating costs. In the present research, the possibility of silicon separation from kaolinite was investigated using bioflocculation method. Firstly, the isotherm graphs of the biofluoclonant absorption including the bacterial strain ( Bacillus licheniformis ) and its polysaccharide excretion on the surface of kaolinite and silica were obtained at pH values of 9, 10, 11, and 12. According to these plots, the highest absorption of the bioflocculants on both of the minerals happened at pH 12. Adsorption density on kaolinite was more than silica, and absorption of polysaccharide was higher than the bacterial cells. Also, both of the minerals showed an increase in adsorption density with pH. Secondly, sedimentation tests were conducted on each mineral using the both bioflocculant at the four pH values. The results showed that employment of bioflocculants changed the mineral deposition in all of the tested pHs. In the control tests conducted without flocculant, precipitation decreased by rising pH to 11. Decline in silica precipitation was stopped at pH 12, while a sharp increase was observed for kaolinite sedimentation at this pH. Sedimentation experiments using the bacterial cells indicated a similar trend. However, mineral flocculation using polysaccharides showed a persistent increase from pH 9 to 12. Finally, using the data obtained from the previous stages, extra tests were carried out using a 50%-50% artificial combination of the both minerals which resulted in the separation of both minerals. Employing the bacterial cells, 98.3% of kaolinite was recovered, and the kaolinite content of the mixture increased by 8.2%. Also, when the bacterial polysaccharide was employed as the bioflocculant, silica content was increased by 7% with the low recovery of 30.7%. These values in the control separation tests were 84.8% and 10.3%, respectively. Finally, it can be concluded that using the bacterial cells as the bioflocculant, an acceptable improve in the kaolinite content with a high recovery is attainable