A fluidized bed coating apparatus for coating liquid onto the surfaces of particles directed into a coating chamber. A liquid spray nozzle assembly disposed below a hollow separator within the coating chamber includes an ultrasonic atomizer for atomizing coating liquid into a fine liquid particle cloud and a pressurized air directing air cap for forming the ultrasonically atomized fine liquid particle cloud into a cone shaped spray pattern and propelling the liquid particles through the separator into an upbed region of the coating chamber for recirculation in an outbed region, and through the separator. A cooling air passageway system is provided within the spray nozzle assembly for cooing the ultrasonic atomizer during operation.