In an apparatus below an uppermost module 7 having a centrifugal flow guide there is an axially positioned nozzle 17 supplying a dressing agent, directed onto a dispersing screen 20 which constitutes a cover of a chamber 19 arranged axially below the nozzle 17 and connected with an external blower 21, whereas above the nozzle 17 on the vertical axis of the body 1 there is positioned a shield 16, whereas below the chamber 19 there is arranged a module 10 having a centripetal flow guide, below which there is positioned another module 7 having a centrifugal flow guide, and the lower end of the body 1 is constituted by a module 10 having a centripetal flow guide.