VFD control methodologies in High Pressure Grinding drive systems

High Pressure Grinding Roll (HPGR) technology is a reliable workhorse in the cement industry. Because of its generally overall lower cost per ton of material processed, HPGR applications have been growing in popularity in recent years in the mineral processing industry. HPGRs can be combined with variable frequency drives (VFD) to provide added process flexibility and reduce roll wear rates. This flexibility and reduced wear can increase uptime and overall mill throughput. The nature of the HPGR mill design with its independent grinding rolls requires an innovative solution for the control of the rolls when driven by a VFD. This paper reviews available drive control methods to determine a solution that will promote low roll wear and maximum grinding efficiency.