The machine casing is made of heavy-gauge, press-formed and calendered steel sheet, so as to allow optimal mixing of the product. The entire structure is reinforced with profiles on the outside. The mixing axis is rotated by a power gearmotor. Both heads are made of heavy-gauge steel sheet reinforced with profiles both longitudinally and transversely and are bolted to the casing to allow easy maintenance operations. The paddles are mounted on a central shaft and are oriented and arranged to allow the best mixing of the product. The shaft is made of solid round steel. Two supports at the ends of the shaft allow perfect alignment and the presence of a low-pressure pneumatic nozzle prevents the depositing of dust or foreign material. There are inspection hatches on the sides equipped with electric sensors and safety locks to allow opening only when the machine is stopped. The unloading system consists of a door operated by one or more pneumatic cylinders, with safety limit switches and a mechanical safety lock system.