disclosed is a two - shaft continuous mixer used for homogenization of plastics , manufacture of compounds of composite plastics and the like . a mixing control apparatus is also provided , in which a gear pump as a material discharge mechanism is directly coupled to a material discharge opening , in which apparatus , a mixing degree is positively controlled within the mixer under the constant feed condition of the pump over the wide range of viscosities under the stabilized operation . movable dams are also provided .