CHARACTERIZATION OF STRENGTH AND STRUCTURE OF GRANULAR AND PRILLED UREA FERTILIZER

Solid urea fertilizers can be produced in two forms: granules and prills. The study of comparison between granules and prills is nearly non-existence and hence it becomes the ultimate goal of this project. Due to different physical structures, granular and prilled fertilizers are distinguishable in terms of their structural strength and properties while their chemical properties remain similar. In Malaysia, there are currently two operating plants producing granular urea, namely Asean Bintulu Fertilizer (ABF) and PETRONAS Fertilizer Kedah (PFK). Comparison of products from these two companies was being investigated. The scope of work includes size distribution, surface morphology, dynamic strength, solubility and moisture content. More than 50% of ABF and PFK granules have the size range around 3.00mm. Prills have an average size of 1.66mm. SEM images of granules exhibited the aggregation of crystals to form a single urea particle while prills appear as one unit. The sticking out structure of granules makes them tend to stick to one another while prills have good flowablity. Naturally, granules have greater strength due to the stacking of crystals which prevent instant damage to the urea. This justification was verified as more fine particles are produced from prills when being milled which defined the idea that prills are easily crushed. For a fixed mass of urea fertilizers, prills dissolve faster in water due to larger surface area. Granular urea fertilizers have higher amount of moisture content compared to prills which causes it have higher tendency to form cakes during storage due to the cohesive nature of water. In short, granular urea fertilizers are relatively better for its superiority compared to prills