Abstract-In this study the movement of ammonium nitrate granules in a fluidised bed pilot plant is investigated for three different perforated plate designs at two different fluidisation velocities each. A qualitative and quantitative study is done to evaluate the degree of mixing that takes place. The attrition breakage for each plate is determined as a secondary objective. The granulation of ammonium nitrate through fluidisation is commonly used in the manufacturing of porous ammonium nitrate.The aim of this project is to make use of particle size analysis to determine the extent of particle movement in a fluidised bed. The bed is initially loaded with layers containing different particle sizes, making it possible to analyse how much mixing occurs while the bed is operated. In subsequent experimentation, a colourant is injected into the fluidised bed while the fluidised bed is in operation. The samples taken from the fluidised bed, representing both distance from the colourant injection point as well as depth in the bed, are being rated on the amount of colourant present in each, indicating how the colourant was distributed within the bed.The attrition breakage in each case is investigated using a mass balance on each of the three sizes of particles present in the bed. An increase in the mass of very fine particles indicates whether breakage through attrition is present and to what extent.