Abstract: An apparatus for high shear mixing of material comprising a hub having a rotation axis, a flange attached to the hub and extending radially outwardly therefrom, an impeller operatively attached to the hub for rotation therewith and axially spaced from the flange and an annular skirt attached to the flange, the skirt having a plurality of openings spaced around the circumference, an annular chamber being formed by the hub, the flange, the impeller and the skirt, the impeller having blade formations adapted to pump the materials being mixed into the annular chamber and out through the openings as the apparatus is rotated about the rotation axis.