An apparatus and method for mixing liquid or a drilling mud with solids and a second liquid is disclosed. The apparatus provides an annular housing having a plurality of mixing chambers. An inlet passageway is tangentially connected to the innermost mixing chamber for feeding slurry material to be mixed with solids axially fed into the same mixing chamber. A discharge port is further provided and connected to the outermost mixing chamber for tangentially discharging the homogeneous mixture of slurry and solid materials from the outer mixing chamber at high velocities to an elevation above the inlet. The mixing operation is enhanced by the liquid/solid mixture spilling over a first partition wall and retaining its rotational velocity and direction of rotation while passing under a second partition wall and finally out the discharge port.