Drying of large volumes of wet agglomerates is often performed in continuously operating fluid-bed dryers. Assuming that the moisture content of the wet agglomerates to be dried is given, the drying process in a specific dryer can be controlled by adjusting the mass flow of wet agglomerates entering the dryer, the air-flow rate, the air temperature and the mass of product which is inside the dryer. The amount of product, which is inside the dryer, can be varied by installing a weir with a defined height at the dryer outlet. Both, the feeding rate and the mass of product inside the dryer are influencing the mean residence time of the product inside the dryer. According to the results obtained in the current study the mean residence time is a useful parameter to control the amount of oversize particles and the final moisture content of the product. (c) 2006 Published by Elsevier Ltd.