Process and apparatus for producing granular materials

摘要

Granular materials having a narrow particle size distribution can be produced according to a novel process by a) spouting the product to be granulated in liquid form into a fluidised bed, b) precipitating the proportions of fines escaping with the off-gas from the fluidised bed and returning them as nuclei for the formation of granules into the fluidised bed, c) influencing the granulation process in the fluidised bed, by adjusting the classifying-gas stream only, in such a manner that granules are produced with a size defined by the classifying-gas stream, and d) removing the finished granules only, via one or more countercurrent/gravity classifiers set in the gas distributor plate of the fluidised-bed apparatus and e) subjecting the granular materials thus obtained to a thermal secondary treatment if required. The novel apparatus for producing granular materials according to the invention essentially comprises a fluidised-bed granulator, - which comprises devices for atomising the product fed in in sprayable form, - which further comprises a system suitable for returning proportions of fines escaping from the fluidised bed and - directly attached to whose gas distributor plate are one or more countercurrent/gravity classifiers. The granular materials which can be produced according to the process of the invention are likewise novel.