Method for preparing a paste by mixing or kneading materials, particularly for making aluminum production electrodes, said method comprising the following operations: a) introducing at an upstream end of a drum the materials to be mixed and kneaded, the drum having an inner surface extending along an axis of revolution substantially horizontal from an upstream end to a downstream end, said downstream end being opposed to the upstream end along the axis of revolution, the upstream end being closed by an upstream plate and the downstream end being closed by a downstream end, the upstream end and the downstream end being fixed relative to the frame and being each constituted by a plate extending substantially perpendicularly to the axis of revolution b) rotating the drum around the axis of revolution and urging the materials via centrifugation against the inner surface of the drum extending from the upstream end of the drum to the downstream end, and mechanically compressing the materials against an inner surface of the drum by means of a roller, an upstream space being arranged between the roller and the downstream end, c) locally dislodging from the inner surface the materials centrifuged by the rotation of the drum and causing them to fall onto a granulating tool substantially arranged to the downstream end, d) cooling the materials in the upstream space by pouring water introduced through an shaft bearing the roller (35, the shaft passing through the upstream pale and the downstream plate and in rotation around an axis of rotation of compression (X") freely relative to the frame, holes being arranged in the shaft and distributed along the direction of the axis of rotation of compression (X") and around the shaft, the holes leading into the core of the shaft which is provided in water at an end of the shaft, e) collecting the materials thoroughly mixed, kneaded and cooled at the downstream end of the drum, the materials being mixed, kneaded and cooled continuously, by performing simultaneously operations a), b), c), d) et e), the materials being introduced at the upstream end (31a, 27, 28) while the materials previously introduced are kept in the drum and other materials, thoroughly mixed, are collected at the downstream end. a) introducing at an upstream end of a drum the materials to be mixed and kneaded, the drum having an inner surface extending along an axis of revolution substantially horizontal from an upstream end to a downstream end, said downstream end being opposed to the upstream end along the axis of revolution, the upstream end being closed by an upstream plate and the downstream end being closed by a downstream end, the upstream end and the downstream end being fixed relative to the frame and being each constituted by a plate extending substantially perpendicularly to the axis of revolution b) rotating the drum around the axis of revolution and urging the materials via centrifugation against the inner surface of the drum extending from the upstream end of the drum to the downstream end, and mechanically compressing the materials against an inner surface of the drum by means of a roller, an upstream space being arranged between the roller and the downstream end, c) locally dislodging from the inner surface the materials centrifuged by the rotation of the drum and causing them to fall onto a granulating tool substantially arranged to the downstream end, d) cooling the materials in the upstream space by pouring water introduced through an shaft bearing the roller (35, the shaft passing through the upstream pale and the downstream plate and in rotation around an axis of rotation of compression (X") freely relative to the frame, holes being arranged in the shaft and distributed along the direction of the axis of rotation of compression (X") and around the shaft, the holes leading into the core of the shaft which is provided in water at an end of the shaft, e) collecting the materials thoroughly mixed, kneaded and cooled at the downstream end of the drum,