Abstract: Described is an apparatus for treating materials which are capable of flow, comprising a container (1) which rotates about is central axis (5) which is inclined with respect to the vertical, with a wall and/or bottom scraper plate (2) which is arranged substantially stationarily with respect to the cylindrical inside wall of the container (1), a discharge opening (3) disposed in the bottom of the container (1) and a rotating tool (6) which engages into the material. To reduce the amount of power consumed, while giving good treatment effects, and to enhance the output of the machine, with respect to the available volume in the machine, it is proposed according to the invention, that the container (1) is driven at a sub-critical speed of rotation, the rotating tool (6) is arranged exclusively at the downstream side of the apex, that the space on the upstream side is free of fittings therein and that the scraper plate (2) is disposed in the vicinity of the apex of the container (1).