Abstract: A hot drying agent discharged from the section for material transport of the bound moisture, having a low moisture content, is recirculated to the front part of the drying area; the moisture content of both of the fed and discharged material is measured and by means of the differential-analogue signal thus obtained the stream of the material to be dried and in a given case the heating of the drying agent is controlled. An apparatus for performing the drying operation is also provided.