The option to improve the shelf life of fertilizers by upgrading the morphology is examined. The researched fertilizer consists of a ternary melt suspension with two fertilizer compounds and an additive. The first part of the study shows that the crystal size of the non-molten fertilizer compound (the remaining solids) has a significant effect on the morphology of granules. Due to the fact, an assumption concerning the roughness and sphericity of granules manufactured with a small crystal size of the suspended fertilizer compound in fluid bed granulator is introduced and proven. The roughness of the granules decreases with smaller crystal size fractions of the suspended solids in the suspension.

Conclusions concerning coverage of the water-repellent finishing and shelf life of the granules are introduced. A reduced roughness of the granules will decrease the dust products in transport processes and hence increase the shelf life. Since dust as attrition products of the roughnesses is one of the key factors to boost the caking of granules. Furthermore, the reduced roughness of the granules will also improve the coverage of the water-repellent finishing. The roughnesses are responsible for failure in the coverage of the coating of granules. Therefore, the coverage of the water-repellent finishing is another key factor for the reduction of caking of the granules and hence thereafter an improved shelf life. An improvement in shelf life could be achieved in the same order of magnitude as the roughness is reduced of the granules.