Abstract: A device for pneumatic treatment of powder materials in a recipient chamber (22), with introduction of two material streams into the above through two inlet tubes (40, 40a), optionally in a counter-current and/or approximately tangential sense and swirled in the recipient chamber (22). The material streams are for introduction at roughly the same level in the container and the tracks thereof are interleaved. The material streams are also introduced at an inclination angle (w) to a radial plane (E) of the recipient chamber (22) which is inclined downwards.