Abstract: The invention relates to a tubular mill for grinding natural and synthetic raw materials, in particular for the cement industry, comprising a horizontally-disposed rotary cylindrical drum, characterized by comprising one or more fixed grinding rollers disposed radially within the drum and supported by a fixed shaft which extends along the axis of rotation, each of said rollers being idle and able to rotate by friction within an annular guide rigid with the inner wall of the drum.

Abstract: This invention relates to a device for controlling the gas temperature in the drying chamber of a moving grate preheater for cement clinker production. The device according to the invention comprises means for feeding high temperature gas for mixing with the recycle gas from the preheater calcining chamber, and means for controlling the temperature and/or quantity of said high temperature gas. It is thus possible to control the recycle gas temperature in order to stabilize it at the most suitable value for treating the material to be dried and preheated.