Abstract: A rotary dryer for drying and mixing particulate material, includes a shell having a pair of conical portions and provided with a jacket to which a hot fluid may be fed, the shell defining a chamber for the material to be dried and mixed. An air-tight closure for the chamber is provided with a jacket to which hot fluid may be fed and through which the material is charged and discharged. A rotary tube shaft extends horizontally from one end of the shell and along the horizontal axis of the shell, the rotary tube shaft being sheathed by a rotary joint pipe equipped with a bearing rotatably supporting the rotary tube shaft. The rotary tube shaft is provided with a plurality of communication paths which communicate with charge/discharge ports located on the rotary joint pipe during rotation of the rotary tube shaft in the rotary joint pipe, the communication paths connecting the jackets of the shell and the closure for feeding the hot fluid.