Optimisation of high shear granulation of multicomponent fertiliser using response surface methodology

This work describes a novel method of producing multicomponent fertiliser granules using high shear granulation. The granulation process was optimised using the response surface methodology technique. The variables used in the optimisation process include granulation time, batch size, impeller speed and binder concentration. Granulation time, binder concentration and interaction between the batch size and granulation time were found to be the main factors affecting the granule median size. The product yield is mainly influenced by granulation time and binder concentration. The interaction between the impeller speed and batch size also have a significant influence on the product yield. Product yield (2–4 mm) of approximately 60% could be obtained with high sphericity and granule strength (> 0.5 MPa). A low product recycle ratio of about 2:3 can be obtained at the optimised process conditions, compared to typical recycle rations of 6:1 which are obtained in typical fertiliser plants.

Surface plots showing effect of impeller speed and granulation time product yield for different binder concentration and different batch sizes.Figure optionsDownload as PowerPoint slideHighlights
► Used design of experiment to study effect of process variables on granulation.
► Product yield of up to 60% could be obtained.
► Product yield is mainly influenced by the binder concentration and granulation time.
► Granule median size mainly influenced by granulation time and binder concentration.