A mixing drier in the form of a spherical mixer comprises an upper vessel shell and a lower vessel shell which can be closed together in a separation plane. A stirrer having a stirrer shaft and stirring elements is affixed to the upper vessel shell. The stirrer axis is inclined to the vertical. The separation plane is perpendicular to the stirrer axis. The stirring elements are located below the separation plane. A hinge is located in the separation plane and allows the vessel of the spherical mixer to be opened for cleaning.