Effects of Segregation on Granulated NPK Sieving – a case study/ Efeitos da segregação na peneiração granulada de NPK - um estudo de caso
DOI:
https://doi.org/10.34117/bjdv5n11-163Keywords:
Mechanisms of Segregation, Recycle Control, NPK granulation.Abstract
Particle segregation is a common, but often neglected problem in bulk solids handling. It is induced by mechanical stresses suffered by a bed of material when vibrated, allowed to freely fall or transfer, provoking particles to reaccommodate size-biased. This phenomenon triggers a series of upsets in production lines. In fertilizer granulation plants, some quality issues of final product and overall process control disturbances can be explained by excess of segregated material being fed to process screening machines. This paper is a case study of sieving inefficiency troubleshooting that took place in an NPK granulation plant in India, where the lack of proper transition between product bucket elevator and a conveyor belt caused material to suffer trajectory segregation. As a result, the granulometry distribution profile on belt was increasingly coarser along its width moving away from elevator’s discharge. When that conveyor fed a pair of screening machines through a stream splitter, one was receiving an excess of undersized particles whereas the other an excess of oversized ones. Even though same flow was being achieved on both machines, a more segregated and homogenous mixture fed to them decreased overall screening efficiency. Poor sieving results in excess of feed to oversize grinders and reduced recycle back to granulator, destabilizing recycle control system and overall granulation process. Given the impossibility of revamping or replacing the existing transition, in this case an inclined chute, palliative measures showed necessary and enough to reduce segregation, increasing screening efficiency to as high as 96% and stabilizing recycle control.
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