An Analysis of a Closed-Circuit Tube-Mill Process to Grind Cement Clinker at Constant Specific Surface Area

Abstract

Based on operating data of a closed-circuit tube-mill process for cement clinker grinding, the following analysis has been made. First, by applying matrix simulation method, the influence of operating or design variables on the steady-state flowrate (P) and particle-size distribution of fine products has been estimated, under the condition that the specific surface of fine products (S_p) is always kept constant by adjusting cut-size of classifier. Next, based on the estimation, some fundamental ideas to optimize operating and design variables have been found out. Main conclusions are as follows.
1) The flowrate of classifier feed (F) to maximize P is strongly dependent on the flowrate of circulating air in the classifier, but is independent of aimed value of S_p. On the other hand, circulating load to maximize P is strongly dependent on aimed S_p. 2) To reduce the specific energy consumption, it is important to select the appropriate capacity ratio of classifier to mill, and also to maintain F at the optimum point.