Among industrial drying processes ,the technology of drying with superheated steam ,which has been know for about a hundred years,has recently been attracting increaseing attention .The circulation of the super-heated stream used as drying gas in a closed circuit system and the possibility of direct condensation of the vapor stream removed from the circuit create favorable conditions for the operation o such drying installations with minimal ecologically harmful emission .However ,the practical application of this technology has hitherto benn confined to non-tacky,wet particle late material .For example ,superheated stream is used in the drying of lignite and sewage sludge and in the srying of beet chips, biomasses and other organic product for use in animal foods ,cf.for examole D.Gehrmann "entwicklungstendenzen der trock nung stechnik in der chenmischen industrie ,chen-ing tech62(1990)A512-520,more particulary sub-chapters 2.2 -3.1.Applicants have worked extensively on the possibility of applying the principle of drying with superheated stream to useful materials and mixtures thereof for use in wetting agents,detergents and/or cleaning products .It has suprisingly benn found that this drying process may also be used or the present and for warious reasons much more sensitive field of application with the hitherto know ,more paricularly ecological end energy-related advantage of drying with superheated stream.Thus DE-A 40 30 688 describes a proces for recovering fine-particle ,solid or free-flowing useful materials or mixtures thereof for wetting agents detergents and/or cleaning product from water-containing preparation thereof usingsuperheated steam as the drying hot gas stream . In this process, frying o the particulate material is terminated before it is endangered by heat