Granulation Without a Drying Step Using Dielectric Heating of Binding Polymers
SourceDry granules that rapidly disperse into water for spray applications are a popular type of formulation for pesticides. Melt granulation processes that do not require a drying step offer lower cost manufacturing of these formulations. Heat activated binding (HAB) granulation processes produce granules without drying by the steps of: heating a powder under tumbling conditions above the melting point of unique water-soluble binding polymer particles, cooling to solidify the binding polymer, and collecting the granules. External heating of large vessels to affect HAB granulation must be done very slowly to avoid hot spots that melt the binding polymer onto the vessel walls leading to caking. Cautious external heating greatly lengthens the process time of HAB granulation. This paper describes dielectric heating of the binding polymer so that granules can be produced continuously, without heating the equipment, and without significant temperature build-up in the powders being granulated.