The mixing effect is increased by separately driven, high speed rotating choppers or multiple choppers, which in cooperation with the plough shaped mixing elements, disperse the lumps and agglomerations or pasty additives with the powdery carriers. These Mixers can be provided with liquid feeding devices, jackets for heating/cooling, choice of seals, vacuum suitability for drying and varied material of construction (like mild-steel, stainless steel, Hastelloy, Monels) to suit the process materials. The Mixer is also provided with a solvent recovery system.