Patent ID: 8318246
Filing Date: 2012-11-27
Classification: B01J,C01P,C04B,C09C

Abstract:
1. A process for preparing encapsulated pigment granules, the process comprising the steps of: (1) loading iron oxide powder by way of a chute into a mixer having spiral blades, the blades being adapted to draw the powder down to a bottom of the mixer; (2) rotating the mixer for 0.5-2 hours to cause the iron oxide powder to continuously cascade within the mixer, so as to form compacted pigment granules of 0.3-1.2 mm diameter; and spraying by a spray bar having a plurality of nozzles, liquid encapsulation solution onto the cascading compacted pigment granules, wherein the liquid encapsulation solution is made by mixing water with polyvinyl alcohol encapsulation powder, to cause the cascading compacted pigment granules to be encapsulated, with the encapsulated pigment granules having a diameter of approximately 0.3-1.2 mm and having a moisture content of approximately 10-14%; (3) while the mixer is rotating, directing heated air of 200-600° C. onto the encapsulated pigment granules, such that the encapsulated pigment granules are dried; (4) continuing the process until moisture content of the encapsulated pigment granules is reduced to about 2% or less; (5) removing the encapsulated pigment granules from the mixer by reverse rotation of the mixer; and (6) directing the encapsulated pigment granules into a hopper.