Influence of roll speed and feed fineness on finish grinding of cement clinker using a High Pressure Grinding Roll

摘要

High-Pressure Grinding Rolls (HPGR) are used in cement plants worldwide. Although the technology is mastered in a majority of applications, design-, scale-up- and operation-chal­lenges still exist today. In addition to modeling throughput, energy requirement and comminution success, the predic­tion and avoidance of malfunctions is of great importance in current research. The performance of the mill is highly influenced by the roll speed and the fineness of the feed. High roll speeds result in increasing vibrations and bearing loads. Combined with high proportions of fines, additional deaeration problems occur when material is fed into the roll gap, which can lead to strong, high-frequency oscillations of the torque, so-called chattering and even to negative torques (backlash).The circulating load is an important parameter influencing the fineness of the feed material and thus the performance of the mill. It strongly depends on the design of the grinding circuit, the target fineness and, in particular, on the efficiency of the installed classifiers. In order to meet this circumstance and at the same time to ensure a justifiable material input and test expenditure, a complete grinding circuit with static and dynamic classifier for plant throughputs of up to 1.0 t/h was set up on a small technical scale at the research center of thyssenkrupp Industrial Solutions AG in Beckum. The present study varied the roller speed between 0.5 to 2.0 m/s and the proportion of fines in the feed between 0 and 75 % in order to investigate the influ­ence of both parameters on the finish grinding of a Portland cement with a target fineness of 4000 cm~2/g according to Blaine.The results are compared with model concepts and are critically examined with regard to their transferability to industrial plants.