Method for applying coatings to solid particles

A process for the formation of coated rounded particles of substantially uniform size which comprises introducing the material to be coated into the inlet end of a rotating drum, the axis of which drum is maintained in a generally horizontal attitude;

• therein maintaining a bed of rolling discrete nuclei particles of substance to be coated in which bed said nuclei are in contact with each other, said rotating drum having lifting flights on the inner surface thereof acting to elevate portions of said bed from the bottom of said drum to a higher point therein;
• releasing said elevated portions of said bed on said lifting flights, and cascading same onto substantially the full upper surface of deflector means, said deflector means fixed in space in the upper hemispherical section of said drum and extending substantially therethroughout comprising two generally horizontally inclined planes defining a generally inverted V configuration, moving said particles away from the apex of said inverted V and toward each of the two bottom edges thereof, each said edge juxtaposed a sidewall of said drum wherefrom said particles free-fall back to the bed of nuclei juxtaposed the bottom of said chamber;
• and spraying localized portions of said particles after their release from the bottom edges of said inclined planes, thereby ensuring that at least a portion of the coating material so sprayed is directed upon a dense cascade of particles which are substantially particle size homogeneous;
• and removing at least a portion of the resulting spray-coated particles from the outlet end of said drum;
• said process characterized by the fact that it ensures that the localized portion of particles, which is sprayed to effect coating thereby, is substantially particle size homogeneous, thereby effecting substantially uniform coatings on each particle released from said lifting flights.