Washington University

Michael Center

Robert E Sparks

Norbert S Mason

A method of melt granulation for powdery material is disclosed wherein the powdery material is discharged onto the upper surface of a heated rotary spreader for migration under centrifugal force to the periphery of the spreader accompanying by melting of a portion of the material and enrobing of non-melted particles by the melted material for discharge as enlarged granules from the periphery of the spreader. To improve the quality of the granules produced, the feed material is supplied to the spreader at two separate locations. The first location is the central portion of the spreader to provide the melted material and the second location is adjacent to the periphery of the spreader. The spreader is preferably in the form of a concave bowl or inverted truncated cone or dish. Feed material is supplied to the first location by a screw feeder extending down the side of the dish and at the second location by a rotary vaned distributor located within the dish which radially flings the feed material onto the inclined dish wall. The process and apparatus is particularly useful for the production of non-sticky granules which are difficult to form when a single central feed of material is used.

Method and apparatus for granulation and granulated product

Method and apparatus for the formation of granules of a larger size or mass of a desired range from a feed stock of smaller particles comprising feeding a meltable powdery material to be granulated, or a non-meltable powdery material with a meltable binder to the surface of a rotating spreader means in the form of a disk or bowl, at least a portion of which has been heated to a temperature above the melting point of the meltable component of the feed material wherein the rate of feeding, the energy input to the spreader means and the rotational speed of the spreader means are controlled so that there is sufficient time for at least a partial melting of the meltable component of the feed material substantially solely by contact with the heated surface of the spreader means, centrifugally spreading the material across the surface of the disk or bowl and dispersing the same from the edge thereof into an atmosphere cooler than the melting temperature to form the granulated product. For certain materials only a part of the powdery feed material is melted forming a liquid film carrying a major portion of substantially unaffected or minimally affected feed material to produce a product comprising individual granules containing a core as the major part of each granule with the original powdery material essentially unchanged maintained in self-sustaining form by a matrix of melted and resolidified particles bonded to each other at their surface.

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St. Louis, MO, United States of America

Michael Center