GRANULATION PROCESS

摘要

A spouted bed granulation process in which the average particle size of the final product is controlled by employing, as seed particles fed to the granulator, a mixture of particles of at least two different average particle sizes and changing the mixing ratio of the respective particles. The mixture is formed of a first fraction having a particle size just below the acceptable range for the final product and a second fraction having an even smaller particle size. Different techniques for obtaining the two differently sized materials are disclosed. In one technique, a classifier classifies the cooled output from the granulator into final product, granules which are larger than final product and granules which are smaller than final product. The smaller granules are stored in a tank from which the first fraction may be drawn and the larger particles are pulverized and stored in another tank from which the second fraction may be drawn. Using the invention the size of the final product can be readily controlled.