in apparatus for spraying water on granular material in a rotating cylindrical pan and for compressing the mixture into pellets . a moisture sensor on said pan provide a signal to a programmable computer controller for providing a constant moisture content on the surface of the pellets . in one embodiment , a liquid nozzle is controlled by a control valve such as to maintain the constant moisture content . in another embodiment , a high intensity mixture is provided for mixing dry powder in varying amount with high moisture material to produce pellets having substantially constant surface moisture when discharged from the pelletizing disc .