Over the last three decades the vertical roller mill has become the preferred mill for grinding of raw materials. The grinding efficiency of the vertical roller mill combined with an ability to dry, grind and classify within a single unit gives the vertical roller mill a decided advantage over a ball mill system. However, despite these benefits, applications of the vertical roller mill for cement grinding are less prevalent.
Keywords: vertical roller mill, model predictive control, proportional integral and derivative control, artificial neural networks, fuzzy logic. 1. INTRODUCTION The VRM is a type of grinding mill integrated with multi functions such as grinding, drying and separation, used for grinding of coal, petroleum coke and minerals.
The resulting vertical mill, shown in Figure 1, offers a relatively high energy density compared to ball mills, attrition mills and other classic vertical grinding systems. Additionally, the mill uses the advanced grinding media separation system at both the discharge and feed sides of the mill to centrifuge the media out of the slurry.
Figure 10.1 shows the difference in energy efficiency between a laboratory ball mill and a stirred mill grinding a gold ore using 6 mm diameter alumina balls as media. At a fine grind size there is a clear advantage in energy consumption for a stirred mill over the tumbling mill.
shown in Figure 2a. This makes the mill much taller than the vertical mill, but allows it to be closely coupled with a cyclone or filter-receiver when required. This mill's clas-sifier wheel and impact rotor have independent drives, and the mill can handle the same grinding applications as the vertical mill. Combined drive.