How To Increase The Output Of Vertical Mill
As a milling equipment, vertical roller mill can process fine powder and ultrafine powder. Its output is not only related to materials, but also related to daily operation habits. Want to increase the output, you must to know as follow:
1. Material Thickness
The crushing effect of the vertical mill depends on the grindability of the material, the applied tension and the amount of material that bears these squeezing forces. The adjustment range of the tension is limited.
If the material is difficult to grind, the new unit surface area consumes energy Larger, if the material layer is thicker at this time, the amount of energy-absorbing material increases, resulting in more coarse powder in the crushing process, which cannot meet the fineness requirements, low output, high energy consumption, large circulation load, and difficult to control the pressure difference To worsen the working conditions.
In the case of difficult grinding, the thickness of the material layer should be thinned appropriately to increase the proportion of qualified particle size. If the material is easy to grind, a large number of qualified particles can also be produced in a thick material layer. The material layer should be thickened appropriately to increase output. Generally, the thickness of the material layer is controlled at about 50mm-80mm.
The amount of material fed into the mill and the amount of finished product must be balanced. The reasonable feeding particle size and particle gradation are one of the important conditions for stabilizing the thickness of the material layer.
2. Water Spray
The main function of the water spray of the vertical mill is to adjust the milling temperature, stabilize the material layer, and reduce the pressure difference within the mill. The amount of water sprayed and the method of water spray in the mill can change the motion resistance of the material on the grinding disc, affect the flow rate of the material, control the length of time the material is ground, and affect the grinding effect.
3. Differential Pressure
The control of differential pressure is a key factor to improve product quality and output. The sum of the local ventilation resistance caused by the hot air entering the grinder’s nozzle ring and the fluid resistance of the fluid filled with suspended material from the top of the nozzle ring to the pressure point form the pressure difference of the grinder.
The size of the feeding amount and the amount of circulating material in the grinding chamber will cause the change of the fluid resistance in the grinding chamber, resulting in the change of the pressure difference. Keeping the pressure difference within the mill stable means that the amount of material entering the mill and the amount of material coming out of the mill have reached a dynamic balance and the cyclic load is stable, which is the prerequisite for stable normal production of the mill.
In production, the pressure difference should be controlled in time and effectively at about 7000pa. The decrease in pressure difference indicates that the amount of material entering the grinding is less than that of the grinding, the circulating load is reduced, the thickness of the bed gradually becomes thinner, and vibration will occur when the thickness is thinner and the grinding will stop.
The reason for the increased pressure difference is that the amount of material entering the grinding is greater than the amount of material coming out of the grinding, which may be caused by a certain link being unreasonable, resulting in a decrease in the amount of grinding out.
4. Outer Circulation
The external circulation material is generally the material after the grinding and the fresh incoming material are jointly milled together for grinding. It can adjust the particle gradation of the grinding material and enhance the grinding effect. The grinding effect can be judged according to the particle state and quantity of the external circulation material.
During normal operation of the vertical mill, the vibration value of the mill should be strictly controlled within a reasonable range, and it should not exceed 0.9mm/s in an instant. The blanking capacity of the vertical mill must be adapted to the capacity of the vertical mill. When the hardness of the material is low and the tension is high, there may be instantaneous air pressure and vibration.
Excessive discharge volume, high separator speed, insufficient ventilation in the mill, and excessive amount of powder generated, exceeding the carrying capacity of the gas through the mill; a large amount of air leakage or uncomfortable adjustment in the system will increase the circulation load in the mill , Suffocation and vibration occur.
6. Air Volume
The power consumption of the product is closely related to the output of the mill. The higher the output, the lower the unit power consumption. The lower the output, the larger the air consumption, which increases the power consumption of the fan. Therefore, under the premise of satisfying the wind speed of the nozzle ring and the dust concentration of the output air volume, the air volume should not be too large.