Abstract: Mixersettler separator is the most widely used extraction equipment in rare earth production process. The volume ratio between singlestage settler and mixer in China’s rare earth industry is generally above 25∶1， which leads to a large floor area， high rare earth accumulation and high entrainment losses. To solve the problem， a new type of mixersettler was designed， and a mixing cylinder was installed in the settler. The aqueous phase entrainment at the settler outlet was studied by ultraviolet visible spectrophotometry and was compared with the case of industrial production process. The experimental results showed that appropriate conditions are conducive to the twophase separation after reducing the settler volume. When the diameter of the ring cover is 30mm， impeller clearance over the tank bottom is 13cm and mixing speed is within 300r/min， the measured aqueous phase entrainment is less than the industrial result of 050%. This proves that the new type mixersettler can meet the demand of industrial production.

Key words: mixersettler, aqueous phase entrainment, mixing speed, impeller clearance over the tank bottom, ring cover size