Abstract: A container mixer typically comprises a mixer inside a container tank. The mixer comprises a shaft and blades mounted on the shaft, an actuator positioned outside the container tank, and a coupler with which the mixer is coupled to the actuator. The container tank has a quick coupling which enables the actuator to be detached temporarily from the container tank. The quick coupling comprises a separate shaft coupling piece, detachable when necessary, fitted between the actuator drive shaft and the mixer shaft in such a way that the motion of the actuator is transmitted by transmission of the shaft coupling piece to the mixer shaft. In addition the quick coupling has quick coupling and quick-release devices which lock the shaft coupling piece between the drive shaft and the mixer shaft.