Vertical roller mills (VRMs) are highly efficient equipment widely used in the raw material grinding and cement production stages of cement production. In recent years, VRM cement mills have been increasingly used worldwide due to their significant energy savings, low pollutant emissions, and compact footprint.
Despite their many advantages, VRMs are more complex in structure than other cement mill types. During operation, the following key operating points require close attention to ensure stable and efficient operation:
1. A stable and appropriate mill bed.
The bed is essential for stable vertical mill operation. An excessively thick bed reduces grinding efficiency, leads to abnormally high pressure differentials, and can even cause bed collapse, impacting the main motor and discharge system. An excessively thin bed can easily cause direct contact between the grinding rollers and grinding discs, exacerbating equipment vibration and accelerating wear of the rollers, grinding discs, and hydraulic systems.
2. Controlling mill vibration intensity.
Excessive vibration not only affects product quality but can also cause mechanical failure. The intensity of vibration is affected by a variety of factors, including grinding pressure, bed thickness, system air volume and temperature, accumulator pressure, and the wear of the grinding rollers and grinding discs. Comprehensive adjustments are required.
3. Set the appropriate grinding pressure.
Grinding pressure is one of the key parameters that determine output and product quality. The pressure setting must be dynamically adjusted based on feed rate, material particle size, and grindability. Too low a pressure will result in a thicker material layer, increased current, larger pressure differential, and more severe vibration. Too high a pressure will thin the material layer, increase vibration, and accelerate component wear. Beyond a certain critical value, grinding capacity no longer improves, but energy consumption increases.
4. Properly control the gas temperature at the discharge port.
Gas temperature directly affects material flowability and the efficiency of finished product discharge. Too low a temperature can cause material stagnation, affecting output. Too high a temperature (e.g., exceeding 130°C) can cause equipment damage, such as jamming of the distributor wheel, loss of roller lubrication, and damage to dust collector bags. Each mill has its own optimal temperature range, which must be strictly monitored during operation.
5. Adjust the system air volume balance.
The system air volume should match the feed rate and is typically adjusted using a circulating fan or kiln exhaust fan. Excessive air volume can cause the material layer to thin and increase vibration; insufficient air volume can thicken the material layer, increasing pressure differentials and current, which also leads to increased vibration. Air volume adjustment must balance grinding efficiency and system stability.
6. Rational Utilization of Kiln Hot Air (Applicable to Raw Material Mills)
For raw material vertical mills, hot air primarily comes from rotary kiln exhaust. During operation, the inlet and outlet air valves must be coordinated to maintain balanced system air pressure and avoid interference with kiln system operation.
As Baichy Heavy Industry, we are committed to providing comprehensive grinding solutions for the global mining and building materials industries. We offer a variety of vertical roller mill models to meet different production capacities and material requirements. Please feel free to contact us for professional selection advice and technical support!
