Abstract：Taking sodium phrophosphate as a dispersant, the low grade Ca-bentonite was purified by the free settling technology based on assistant treatment of ultrasonic wave. The effect of dispersant concentration, ultrasonic time, ultrasonic power, agitating time, agitating temperature,agitating rate on the content of bentonite was determined. The raw bentonite and purified bentonite were characterized by XRD. The results show that the ultrasonic power and ultrasonic time have significant effect on purification of bentonite, and the dispersant concentration and agitating time have little effect on purification of bentonite. With the best condition for purification, the content of montmorillonite increases from 59.71% to 99%, the recovery rate reaches 81.33%, the methylene blue adsorption increases from 0.263 9 g/g to 0.441 9 g/g, and the swelling index increases from 5 mL/g to 14 mL/g.

Keywords: bentonite; purification; ultrasonic wave; free settling