Installation, operation and maintenance of ball mill

Installation of ball mill

The quality of the installation is the key to ensure the normal operation of the ball mill. The installation method and sequence for all types of ball mills are roughly the same. To ensure smooth operation of the ball mill and to reduce the risk to the building, the ball mill must be installed on a reinforced concrete foundation of 2.5 to 3 times of its weight. The foundation should be laid on solid soil and should be at least 40-50 cm away from the workshop’s foundation.

When installing the large ball mill, the main bearings should be installed first. In order to avoid aggravating the wear of the hollow journal and the bearing lining, the elevation difference of the two main bearings’ base should not exceed 0.25 mm per meter of length. Next, install the drum of the ball mill, combined with the specific conditions, the pre-assembled drum can be installed directly, or in several parts, the journal and the central line of the ball mill should be checked and adjusted, the concentric error must be guaranteed less than 0.25mm per meter length. Finally, install the transmission parts (pinion, shaft, coupling, reducer, motor, etc.). In the process of installation, measurement and adjustment should be made according to the product technical standards. Check the radial swing of the ring gear and the meshing performance of the pinion; the concentricity of the reducer and the pinion; and the concentricity of the motor and the reducer. When all the installation is in line with the requirements, can the foundation bolts and main bearings base’s concrete be poured.

Operation of ball mill

To make the high rate of operation and better effective grinding, the operation and maintenance procedures must be strictly observed. Before starting the mill, check whether the connecting bolts are tightened; check the fastening conditions of gear, pinion, couplings, and the feeding system. Check whether there is enough lubrication oil in the tank and reducer, whether there is any fault in the whole lubrication device and instrument, and make sure the lubrication pipeline is in good conditions. Check if there is any debris around the mill and classifier that may hinder the operation, then check the contact of ring gear and pinion.

The order of starting procedure is to start the lubricating pump of the mill first, ball mill will be started only when the oil pressure reaches 1.5-2.0 kg/cm², next start the spiral classifier, when they run normally can start to feed the ball mill.

During ball mill operation, the bearing temperature should be checked frequently, it should not exceed 50 to 65℃ . Always pay attention to the voltage, current, temperature, sound of drive motor. Pay attention to the lubrication system at all times, the oil in the oil tank shall not exceed 35 to 40℃.
The pressure of the oil supply pipe should be kept within 1.5-2.0 kg/cm². Check the lubrication of the ring gear and pinion, main bearings, classifier reducer and other transmission parts, and observe the feeding and discharging of ball mill, the drum, the discharge box, the classifier overflow tank and the sand return tank, make sure there is no blockage. Always pay attention to the changes of ore conditions and take appropriate measures accordingly.

Before stopping the ball mill, stop the ore feeding first, after the ores are processed and discharged from the ball mill, can stop the ball mill motor and finally stop the lubrication system. With the help of the classifier’s lifting device, lift the spiral out of the sand surface, and then stop the classifier.

Ball mill failure, causes and its elimination method

The phenomenon of failure Causes Elimination method
The main bearing melts, the bearing smokes, or motor overload, power failure
  1. Lubrication system stopped working
  2. Sand or soil are fallen into the bearing.
  1. Clean and wash the bearing, change lubrication oil
  2. Repair the bearing and journal, or change to new ones
When the ball mill starts, the motor overloads or cannot start No running by subsidiary drive system Subsidiary drive running first, then start the ball mill
Oil pressure too high or too low
  1. blockage of oil pipe, insufficient oil quantity.
  2. The oil viscosity is not suitable, too dirty, the filter is clogged.
Change lubrication oil, or add enough oil, make sure the pipe flows smoothly
Motor power supply is unstable or too high
  1. Ore feeder is loosened.
  2. Debris in the returned sand return.
  3. Poor lubrication of hollow shaft.
  4. Excessive density of discharge.
  5. Unbalanced wearing of drum liners cause unbalanced weight of the ball mill
  6. Excessive wear of gears.
  7. Fault on the motor circuit.
Fasten the feeding system,improve lubrication system, change drum liners, adjust or change or repair the gear and pinion, eliminate power supply fault
Bearings heating
  1. ore feeding is too much or too less; lubrication oil is not qualified or is dirty
  2. Improperly installed bearings or falling debris
  3. The lubrication system does not work
Stop feeding, check the causes, change dirty oil, clean bearing, check the lubrication system
Ball mill vibrating
  1. Gear and pinion do not contact well, or severely wearing
  2. Foundation bolts or bearing bolts are loosened
  3. Ring gear connection bolts are loosened
  4. Transmission bearings are severely wearing
Adjust the gear and pinion contact, fasten the bolts, repair or change bearing bush.
Sudden strong vibration and abnormal sound
  1. Iron impurities are fallen to the gear meshing gap.
  2. Pinion shaft crosstalk.
  3. Pinion is broken.
  4. Loosen of bolts on the bearings or on the foundation.
Clean the impurities, fasten the bolts, change the broken pinion
Slurry leaking in the places of drum liner bolts, joint of end cover and drum
  1. Connection bolts are loosened
  2. Drum liner bolts are loosened or broken, sealing pads worn out
Fasten or change the broken bolts, add sealing pads

Maintenance of ball mill

In order to ensure the safe operation and improve its integrity rate, and extend the ball mill’s service life, it is necessary to do the planned maintenance. Inspection work is divided into three kinds,

  • Minor repair: once a month, including temporary accident repair, mainly small change, small adjustment. The focus is on the replacement of easy-to-wear parts, such as the liner of the ball mill, the feeder scoop head, and adjusting the meshing of bearings and gears. Repairing various parts of the leakage.
  • Medium repair: generally carried out once a year, the equipment components for the larger cleaning and adjustment, replacement of a large number of easy-to-wear parts.
  • Overhaul: In addition to the completion of medium and small repair tasks, focus on repairing and replacing the main parts, such as hollow shafts, ring gear, bearings, etc. The time interval of overhaul is determined by the degree of damage of these parts.
  • The average life and minimum storage of ball mill wearing parts are shown in the table

    Wearing parts name Material Life time(months) Recommend backup quantity
    Drum liner High manganese steel 6-8 2 units
    End cover liner High manganese steel 8-10 2 units
    Grate liner High manganese steel or chrome steel 6-18 2 units
    Main bearing bush Babbit alloy 24 1 unit
    Transmission bearing bush Babbit alloy 18 2 units
    Pinion 40Cr 6-12 2 units
    Ring gear Casting steel 36-48 1 unit
    Liner bolts Steel 6-8 1 unit