Mixing mechanism for a mixing machine

A mixing mechanism for a mixing machine, comprising a shaft rotatably mounted in an at least partly cylindrical container of the said machine, arms extending radially outwardly from an inner end thereof connected to the shaft to an outer end thereof, mixing tools mounted on the said outer ends of the arms, and plate-like extensions mounted on the rear sides, as viewed in the rotational direction of the mixing mechanism, of at least some of the arms, said mixing tools and extensions being disposed in a helical arrangement relative to said shaft wherein the mixing tools and extensions of adjacent arms are axially spaced and angularly offset from one another, said mixing tools being constructed and arranged upon rotation of said shaft to stepwise axially convey a material being mixed between adjacent extensions with the material being impinged upon the extensions, and at least one of said extensions having a cavity therein which communicates with a circulation system leading through the shaft for circulating a heating or cooling medium, said cavity having an inlet and an outlet which lead into the respective arm or shaft.