Method for the homogeneous complete encapsulation of individual grains of pourable material and apparatus for its production

Claim 1

Method for the uniform, fully enclosing surface coating of individual particles of pourable materials having nearly uniform particle size with either a smooth, rough or scabrous serrated surface, in a fluidizing fountain with heated air under use of an inorganic and or organic coating material in the form of a suspension or solution, characterized in that a predetermined quantity of the material to be coated within a steep funnel-like upwards enlarged container, having a shorter less steep funnel-like lower segment located at the bottom of said upwards enlarged container by means of injection of a heated air stream at controlled velocity in ascending vertical direction is forming a fluidized fountain of limited height and diameter incident to the middle axis, thereby forming a core zone; injection from below and in the same direction as the heated air by means of one or several injection nozzles, located at the lower end of the container of the suspension or solution in an upward direction with a nozzle spray angle of between 30° and 60° at a predetermined mass/time ratio into the core stream of high volume concentration and the complete, uniform deposition of the suspension on the surface of the material, and simultaneous drying of the treated material during the ascent in the core zone and its descent within the peripheral, reduced air stream pressure, sliding along the vessel wall into the funnel-shaped lower container segment towards the fluidizing fountain and the repeated cycling of this processing step until the predetermined coating quantity has been applied and the drying of the surface coated material to a prescribed moisture content, wherein said steep funnel-like, upwards enlarged container has either a circular or polygonal configuration whose upper portion constitutes a body of increasing diameter wherein the diameter ratio of the upper part, measured from the bottom to the top is in a ratio of 1:1.5 to 1:4.5 and said shorter less steep funnel-like lower segment opens into said upper portion and has sides which form an angle relative to the perpendicular of 20° to 50°, said container equipped at the upper and lower end with screen closures consisting of exchangeable screens of maximum free area with a mesh size smaller than the smallest particle of the material to be coated.