LUM Series Ultrafine Vertical Roller Mill

Base on Zenith abundant experience in producing vertical grinding mill and the latest technology from Taiwan &Germany, Zenith developed the LUM Series Ultrafine Vertical Roller Mill, which gets high reputation from customers. It sets grinding, drying, classifying and transportation as a whole and take little space. What’s most important is that it effectively reduces the investment cost.

  • Features
  • Technical data

* It is quite environmentally friendly, LUM is of little dust and noise.
* The final products has little iron and the whiteness and purity are quite high.
* LUM has excellent grinding-efficiency for the special design of roller shell and grinding plate curve.
* LUM use PLC/DCS automatic control system, well save the cost of operators.

Vertical roller mill process

Vertical roller mill process - from the energy point of view, the grinding of different materials alone grinding, and then mixed with the preparation of cement, grinding process has become the direction of development. To make full use of slag resources, turning waste into treasure, improve the environment.

From the energy point of view, the grinding of different materials alone grinding, and then mixed with the preparation of cement, grinding process has become the direction of development. To make full use of slag resources, turning waste into treasure, improve the environment.

1 .stable bed

Maintain a stable bed, which is the basis of the roller mill bed grinding, the normal operation of the key. The thickness of the material layer can be adjusted by adjusting the height of the retaining ring. The retaining ring is the key part of the Vertical roller mill. Its function is to maintain the grinding material layer. The wear degree of the retaining ring affects the stable operation of the mill. The appropriate thickness and their correspondence with the output of the mill, the control operator should be in the usual operation of the process to grasp the crystal clear. The material layer is too thick to reduce the efficiency of grinding, too thin layer will cause vibration. Such as the roll to increase, the resulting powder and more material layer thinning; roll reduction, disc material thicker, the corresponding return of the material, material layer thicker. Grinding within the wind speed increase, increase the internal circulation, material layer thickening, reduce wind speed, reduce the internal circulation, material layer thinning. In the continuous production practice, we concluded that the roller mill grinding roller compaction of the material bed thickness control in 50 ~ 60mm is appropriate.

In the course of the operation of the control operator should be based on the material layer, the amount of material, vibration and other parameters to determine the block ring wear. Mill under normal operating conditions, feeding volume of 140t / h, vibration value of 3.0 mm / s, back to the amount of less than 10t. Once the mill is running for 4000 hours, the amount of powder back in the 60-80t / h or so, Vertical roller mill vibration value of 9 mm / s, the Vertical roller mill feed volume gradually reduced to 100t / h, still can not run The Immediately stop grinding and grinding inspection and measurement, found that the block ring wear serious, the material particles in the process of moving toward the edge of the disc by the smaller resistance, resulting in grinding material in the disc on the residence time is shortened, a substantial increase in powder back. To this end, has been worn by the block ring of the implementation of the surfacing repair measures, while the mill of the two main roller, the separator after the maintenance of open blade grinding, production in good condition, mill into, the material in the Balanced state. The welding of the retaining ring, both to improve the service life of retaining ring and let us know the role of the block ring more thorough, that is: the block ring after welding, retaining ring and roller sleeve end gap becomes smaller, so that the material Particles in the process of moving to the edge of the disc by the high resistance, not only to avoid the phenomenon of material bypass, but also to ensure that the grinding material in the grinding disc on the residence time.

2 .control the grinding pressure

Grinding pressure is one of the main parameters to control the fineness of finished products. As the weight of the roller itself is certain, in the production mainly by changing the size of the hydraulic system grinding pressure to meet the needs of grinding materials. As the grinding pressure increases, the particle size of the material becomes smaller and the system yield increases. But after reaching a certain threshold to continue to increase the grinding pressure, the main motor current continues to increase, the power consumption per unit of product increases, the mill vibration may increase. At the same time, the wear and tear of the grinding wheel also increased, and its service life decreased. On the contrary, the mill material layer gradually thickened, the main motor current increased, the mill pressure increased, During the debugging period, when the feeding amount is 90t / h, the grinding operation pressure is set to 6.5MPa. With the gradual adjustment of the output to 140t / h in the future, the operation pressure is gradually increased to 7.5MPa, Stable operation state, and the finished product surface area can reach 450-480m2 / kg control requirements.

3 .ventilation control

Vertical Roller mill mainly rely on air flow to promote the material cycle. Ventilation is to ensure that the mill into the material balance of the key. When the air volume is too large, too much material on the disc is brought out, so that the mill material layer in the lower limit, the disc pressure drop, the main motor current decreases, the vibration value increases. If the air volume is insufficient, the finished product can not be brought out in time, so that the disc pressure increases, the main motor current increases, the mill material layer thicker, the powder increased significantly, the mill may be due to the lack of necessary "soft Pad "caused by vibration, resulting in grinding stop. In the daily production, the control operator in accordance with the normal parameters to determine the fan and its valve operating conditions, according to changes in air volume to determine whether the fan valve is in a smooth state, and timely contact with the post, so that they can at any time Grasp the mill production dynamics, to ensure the stable operation of the mill.

4 .to ensure a certain grinding temperature

Vertical roller mill is a grinding and drying equipment, grinding gas temperature is a measure of whether the normal operation of a comprehensive index of drying. In order to ensure good raw material drying, grinding material moisture content of less than 1.0%, if the grinding gas temperature is too low, indicating insufficient drying capacity, finished water, not only on the large bag filter has an impact, and may lead to slag grinding is not fine , The system's grinding efficiency is reduced. When the grinding gas temperature is too high, the material is quickly drying, but will make roller, grinding wheel reducer bearing temperature, shorten the service life of the equipment. Through the continuous improvement in the production and improvement, and gradually summed up: Vertical roller mill out of the gas temperature control in the 95 ~ 105 ℃ is appropriate.

In addition, the grinding gas temperature changes, feed volume is not easy to control. As the slag moisture has a certain fluctuations, resulting in uneven heat consumption, its intuitive performance for the Vertical roller mill of the sudden changes in the export temperature. In particular, when the slag moisture is more than 8%, the outlet temperature drops sharply below 90 ℃. If the parameters can not be adjusted in time, the interlocking jump will be caused by the low temperature. So the stability of slag moisture is the key, we take the measures are: First, the accumulation of sufficient slag, control of water ≤ 8%; Second, adjust the hot air furnace temperature and the opening of the wind valve, the grinding temperature control 100 ° C to 105 ° C. The latter not only solve the problem of large temperature change caused by slag moisture, but also solve the problem of adjusting speed and adjusting effect. At the same time, due to the sufficient heating, the drying and the increase of the ratio of gas to material. Should pay attention to is: stop ingredients, the temperature rise is not conducive to the safe use of dust bag, to be timely cooling.

5 .Vertical roller mill gas erosion wear

The wear characteristics of the mill are both abrasive wear and jet wear. Squeeze wear occurs mainly on the grinding parts and produces slippage, and jet wear mainly occurs in the internal parts of the mill subjected to airflow carrying dust.

The main shaft is also made of wear-resistant steel plate, because the roller shaft and the mill shell by the soft rubber seal , The normal work, the main roller up and down displacement, soft rubber seal performance is poor, in the mill under the strong negative pressure, the mill in the formation of air leakage, strong airflow will be here to wear steel plate erosion, grinding this point the most serious wear , In addition, grinding within the circulation of other parts of the strong erosion caused by, can not be ignored.

During the inspection period, we found that the main roller shaft and the soft connection seal the lower part of the area about 10 mm round pit, shape like a hat, if not timely repair, may wear through the shell. We use the maintenance opportunities on the separator, grinding liner to check, maintenance, to ensure the reliability of Vertical roller mill operation, reduce wear and tear against the dangers of grinding.

In the control operation, according to the actual situation to adjust the main fan of the inverter speed, the mill pressure drop, into the mill negative pressure, the mill negative pressure can reflect the size of wind and wind speed. Pressure drop large, negative pressure that large wind speed, air volume is large; otherwise the corresponding wind speed is small. The stability of these parameters that the stability of the air volume, thus ensuring the stability of the bed.

6 .Vertical roller mill machine system

Separator rotor blade a total of 400 tablets. The cage has an opening groove, the blade is fixed in the groove, the outer part is pressed by the clamping piece, and the clamping piece is fixed with bolts. Vertical roller mill running 4000 hours later, outside the slagging hammer valve found at the bar, identified as the separator blade. Stop check the separator on the rotor cage on the outer edge of the open slot wear serious, resulting in high-speed rotation of the separator when the rotor blades fly out. In order to avoid the recurrence of this situation, we in the cage rotor erosion area along the circumference of a circle φ6.5 round steel to protect the card slot wear, and do dynamic balance test, smooth operation. Operators in the adjustment of the separator speed, increase or decrease the speed of the range should not be too much, to gradually adjust to the normal state, in addition, according to laboratory laboratory results to adjust, try to avoid high speed, overload operation.

7 .into the grinding material clean

As the slag often contains iron slag, large pieces of debris, such as can not be cleaned, not only will increase the mill grinding part of the wear, but also cause the card, blocking the phenomenon, thus affecting the mill production and continuous operation.

In the process design, in order to mitigate wear, the metal detector is used to detect the iron-containing material and interlocking the iron-containing material for efflux. The number of rows is determined by the sensitivity of the metal detector, the sensitivity is too high, the number of rows increased, the mill material layer thinning, mill vibration value increases, the main motor may be due to material thin vibration stop. Outside the set time to be as short as possible, if too long, the mill will break the material too long, the corresponding time to increase the vibration.

In addition, the post staff to ensure that the grinding of the belt and outside the removal of the efficiency of the operation of the iron, in time to clean up the slag mouth slag, to avoid iron and more plugging slag mouth card dead iron caused the belt to jump, causing unnecessary downtime.

Material stability, the equipment is normal, the accuracy of the mill is the fundamental operation of the mill, the process of balance with the equipment to change the small leather is to achieve high quality, high yield of the key. The operator through the changes in the parameters, the application of process balance to solve the common problems in the production of Vertical roller mill, timely adjustment of process parameters, accurate judgments, predict the occurrence of various circumstances, in order to ensure the normal and efficient operation of the mill.

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