Mixing apparatus

A mixing apparatus comprising a container having a separate enclosure, first and second mixing chambers containing respectively first and second bladed rotary impellers and disposed within said enclosure, the mixing chambers having respective inlets disposed in oppositely facing relationship, the container being arranged to receive material to be mixed supplied to an opening thereof and to supply said material in a first direction into the first mixing chamber through its respective inlet, means surrounding the first impeller forming generally radial openings and being arranged in shearing relation to the blades of the first impeller so that material urged radially outwardly through said openings into an intermediate chamber by rotation of the impeller is subjected to a shearing action, the enclosure being arranged to receive material leaving the first mixing chamber and to communicate with the inlet of the second mixing chamber in a second direction opposed to said first direction, further means surrounding the second impeller forming generally radial openings and arranged in shearing relation with the blades of the second impeller so that material urged outwardly through said openings by rotation of the second impeller is subjected to a shearing action, and a discharge chamber having an outlet and arranged to receive material passing through the openings of said further means and being so constructed and arranged that receipt of such material creates an over pressure in the discharge chamber such that material may be discharged under pressure through said outlet.