chamber the bottom of the device is a perforated plate containing larger holes under the inner coating tube the liquid spray nozzle is located in the center of the base and is position to permit the circulation of particles from the outside annular space to the high velocity airstream within the coating chamber the ammonium persulfate particles move upwards in the center where coating and efficient drying and water vapor solvent removal occur at the top of the coating chamber the particles discharge into an expansion area and then flow down as a gas solid suspension into the annular space surrounding the center coating chamber the coating mixture is applied using an atomizing nozzle at a temperature of 25 u00b0 c an atomizing air pressure of 25 psi and an airflow of 25 scfm at a spray flow rate of about 8 g min after the coating is applied to an average of about 25 of the weight of particles the finished encapsulated ammonium persulfate has a temperature of 15 u00b0 c following drying and overnight storage in a container the coated particles are not separate but form one or more clumps that are difficult to break up another encapsulated ammonium persulfate particle preparation is made as follows about 1000 grams of 20 50 mesh u s sieve series ammonium persulfate obtained from fmc corporation are placed in a versaglatt gpcg i fluidized bed apparatus the versaglatt unit is set up to provide top spray by insertion of a top spray insert and a three micron filter bag is utilized the spray nozzle is placed in the lower position on the top spray.