2006 Volume 92 Issue 12 Pages 742-747
A numerical simulation model was developed to analyze the granulation kinetics by using the Discrete Element Method (DEM). The experiment of granulation was performed to understand the actual granulation behavior of iron ore particles. The granulation rate goes up with a decrease in a particles charge ratio and with an increase in a rotational speed of a drum mixer in the experiment. The granulation could be consisted of two processes: One is "a growing process" and the other is "a breaking process". The former would be related to the rotation of granules and the latter would be dependent on the impact, which granules receive from others and/or a drum mixer wall. Then the rotational kinetic energy and the impact energy of a granule were calculated by using the DEM simulation. A granulation energy composed of both the impact energy and the rotational kinetic energy was proposed for analyzing the granulation kinetics. It increases as the rotational speed of the drum mixer rises and as the granule charge ratio drops. The granulation energy would be correlated with the actual granulation process. When the drum mixer diameter becomes large, the granulation energy decreases. When the drum mixer is leaned, the granulation energy becomes larger than at the lean of 0 degrees. That is, the drum mixer has a possibility to improve a granulation process. When the drum mixer is leaned further, the granulation energy rapidly decreases at the lean of 60 degrees. This means that the optimum leaning angle must exist.