The vortex-type cleaners are used for removing lightweiht and sticky contaminants, mostly foamed polystyrene granules and pieces of plastics out of the paper stock in waste paper stock preparation lines. The vortex-type coreclean cleaner is the basicelement of cleaning plants arranged in up to three stage batteries. The high cleaning efficiency of various tyoes of contaminants, particularly of polystyrene “foam” as well as a high operation reliability are the advantage of these cleaning batteries. A sexondary effect is the deaeration of the cleaned stock.