Influence of the pelletizing process parameters on the breakage behaviour of the received alumina oxide pellets

摘要

Pelletizing is a common optimization process of the mechanical properties of various powder materials. The improvement of flow behaviour, dosage and the increase of bulk density are only a few the goals that this size enlargement concedes. Anyway, the properties of the produced pellets depend on many factors, whose influence is not completely studied. In order to investigate the effect of process parameters on the mechanical strength of final products, industrially produced alumina oxide (gamma-Al2O3) granules as primary model particles were pelletized in a laboratory rotating pan-pelletizer (spheronizer). The processing time for all pelletizing batches was 20 min. Solution of viscoelastic polymer-hydroxypropyl methylcellulose was used as binder. Its concentration was increased until finding of the most suitable binder content for the model pellets. The rotational velocity of the pan-pelletizer was varied in order to find the optimal speed, which provides pellets with improved properties. The influence of the process parameters on the received pellet product properties like density and porosity, size distribution, breakage behaviour and breakage probability was also analysed. The solid bonds between the single primary particles were investigated using light and scanning electron microscope. The conclusions from the experimental work help us to understand the basics of pelletizing processes and tend to develop and facilitate the operating principle with particle populations in science and industry. The result should provide base for carrying out of Discrete Element Method simulations, which should enlighten the process of irregular pellet breakage.