Apparatus and process for coating particles

An apparatus for the continuous coating of fertilizer substrate particles comprising:

• a plurality of fluidized bed zones for maintaining fertilizer substrate particles in an essentially fluidized condition;
• means located in at least two of said fluidized bed zones for applying a coating material onto particles in said fluidized bed zones, to provide a plurality of fluidized bed coating zones;
• means for continuously feeding fertilizer substrate particles into a first fluidized bed coating zone;
• transfer means for transferring said particles from a first fluidized bed coating zone to a second fluidized bed coating zone;
• and
• means for continuously removing substrate particles from the second fluidized bed coating zone, characterized in that each said fluidized bed coating zone has a higher gas-velocity region and a lower gas velocity region;
• and said transfer means comprises a conduit having an upper opening in a higher gas-velocity region of an upper portion of the first fluidized bed coating zone and a lower opening in a lower gas velocity region of a lower portion of the second fluidized bed coating zone so as to cause particles from said first fluidized bed coating zone to enter said conduit at said upper opening, and to exit said conduit at said lower opening into said second fluidized bed coating zone, said higher gas velocity region being a central longitudinal region passing through each fluidized bed and being located between longitudinal lower air velocity regions on each side of said higher gas velocity region.