1. Material Characteristics
Excessive Moisture Content: Excessive moisture in the incoming material can cause it to adhere to the liner, baffles, or grate gaps, forming a blockage layer. For example, limestone containing excessive amounts of dirt can easily cause blockage at the wet mill inlet.
Excessive Particle Size or Contains Impurities: Raw material particles exceeding 15 mm or contaminated with foreign matter such as iron filings can hinder material flow and cause equipment blockage.
2. Abnormal Equipment Operating Parameters
Poor Ventilation: Inadequate ventilation within the mill can lead to moisture entrapment, exacerbating material adhesion and preventing the timely discharge of fine powder. Common causes include baffle plate sludge, clogged dust collectors, or system leaks.
Imbalanced Slurry Concentration: In wet ball mills, excessive slurry density (over 1220 kg/m³) increases flow resistance, while excessively low density reduces grinding efficiency. Improper speed: When the drum speed is below 75% of the critical speed, material is not adequately thrown away. When it is above 85%, the centrifugal force is too strong, both of which can easily cause blockages.
III. Mechanical Defects
Blocked grate plates/grate holes: Debris or paste that has not been cleaned for a long time can completely block the grate slots, requiring manual cleaning after stopping the mill.
Worn liner or steel balls: Liner wear exceeding 5 mm or improper steel ball gradation (e.g., fill rate > 40%) can reduce grinding efficiency and lead to material accumulation.
Feed system malfunction: A broken screen, improper water pipe design, or a low material level in the stabilizing bin can all cause blockages.
IV. Improper Operation and Maintenance
Overfeeding: Exceeding the mill's processing capacity can lead to material accumulation, manifesting as a sudden drop in current and an increase in differential pressure.
Foreign matter intrusion: Lost maintenance tools or loose bolts can instantly change the material's trajectory, causing sudden blockages. Lubrication Failure: Bearing wear or oil line blockage can indirectly lead to equipment malfunction and increase the risk of blockage.
5. Auxiliary System Failure
Decreased Separator Efficiency: Excessive return of powder increases the circulating load, leading to system overload.
Temperature Control Failure: Excessive temperatures within the mill reduce grinding efficiency and require water spraying or watering.
