The fundamentals assumptions of batch, fluidized bed drying kinetics of fine diameter materials in semiflow apparatus have been presented. There has been used model of fluidized bed drying, which consist two zones: emulsion zone and bubbling zone with taking into consideration the presence of solid particles in the bubbles. The pseudostationary of bubbling zone and conception of moisture medium concentration are the essentials assumption of the model. The results of computation have been verified by experiments.