By: Ashley August 18, 2019 Last Updated :November 28, 2019
Since the vertical kiln cement plant uses the small ball mill, the grain size of raw material can greatly affect its capacity and quality. The smaller the particle size, the higher the yield and quality of the ball mill. On the contrary, the larger the particle size, the lower the output and quality of the mill, and the higher the power consumption.
The wear resistance of raw material refers to how easy the high energy ball mill is to grind the material. National standards stipulate that using Wi (kwh / t) represents the grinding index. The smaller the grinding index, the better the material is ground. The cement factory is accustomed to using the relative grindability coefficient to indicate how easy it is to grind the material. It uses the experimental small mill to compare the material to be tested with the standard sand to achieve the specified fineness value and calculate the time of grinding.
As for the dry grinding method, the moisture of raw material can affect ball mill capacity and quality. The higher the moisture content of the milled material will cause saturated or greasy so that the capacity and quality of ball grinding machine will be reduced. Thus, the raw material with high moisture should be dried before grinding through the ball mill machine.
High energy ball mill
If the temperature of the raw material and the impact friction of the grinding body is too high, the temperature inside the ball mill will be excessive and the ball will stick, which will reduces the ball mill capacity and affects the quality of ball mill. Meanwhile, The ball mill cylinder is affected by thermal expansion and affects the long-term safe operation of the ball mill. Therefore, you must strictly control the temperature of raw material.
The finer the fineness of the material to be ground, the lower the output.
For ball mills of the same specification, the closed circuit process yields 15-20% higher than the open circuit process. In the closed circuit operation, choosing the proper powder selection efficiency and cycle load rate is an important factor to increase the ball mill capacity.
Some grinding aid will affect the effect of grinding. Most commonly used grinding aids are organic substances with strong surface activity. In the processing of grinding, the grinding aid can be adsorbed with the raw material, and this will accelerate the crack propagation in the material pulverization, reduce the mutual adhesion between fine powders, improve the efficiency of grinding, and is conducive to the energy saving and high yield of the ball mill. The national standard stipulates that the grinding aid may be added during the cement production process, but the addition amount shall not exceed 1%.
Adding a little cement grinding aid to improve the effiency of ball mill grinding during the woking. Since an enterprise uses the cement grinding aid, the increase rate of ball mill has been increased more than 10%, the power consumption per unit can be reduced by about 10%, and the blending amount of mixed materials is increased by about 5%.
The moisture of raw material entering the plant should be strictly controlled and carefully reviewed, and the temperature of the grindled material should be strictly controlled within the scope of the process. In order to ensure the stable capacity of ball mill grinder, the comprehensive moisture of raw material should be less than 1%.
In order to ensure the wear resistance of raw material, the first is to choose the clinker with good wear resistance, and the second is to choose mixed material with good activity and resistance.
In order to ensure a virtuous cycle of internal ventilation, all ventilation ducts should be cleaned regularly under normal production conditions. The dust collector is cleaned once a week and the warehouse should be cleaned up when the machine stop. The pulverizer is ventilated, and the efficiency of the powder selection should be properly adjusted to ensure the steady improvement of the output and quality of ball grinding mill.
Increasing the ball load when the device configuration allows. According to the actual measurement of the grinding balls consumption per ton to determine the number of supplementary grinding balls. Supplementing the ball mill media according to changes in ball mill current, grinding sound, output and quality during daily production. Generally, a warehouse can be used with 3-4 grade balls, and fine grinding bins can be 2-3 grades.
Three types of ball mill grinding
During the control of production, our control of cement fineness mainly adopts sieve analysis method and cement specific surface area method. The 0.08mm sieve residue should be controlled in the range of 2.5% to 3%, and the specific surface area of cement should be controlled in the range of 360 to 375m2/kg.
Using the method of “more broken and less grinding” to control the size of raw material. The second is to control and track the particle size of the mixed materials to truly achieve the rationalization of various material sizes.
The steel balls are the important ball mill media. They produce abrasion and peeling by the collision friction between the steel ball and the material, and the balls of the ball mill. During the working of the ball mill, whether the grading of grinding steel ball is reasonable is related to the working efficiency of the ball mill equipment. Only ensuring a certain proportion of various balls can the grain size structure of the material be adapted to achieve a good grinding effect. Reasonably selecting the grading of ball mill ball is an indispensable measure to improve the quality of ball mill machine. Here we will see how we can get a reasonable grading of the ball mill media.
If you want to process hard rock materials, the grinding balls should have big impact, and the ball mill balls also need the big size. The harder raw materials, the larger diameter of steel ball is. The ball diameter of double-storage partition should be smaller than the single-layer compartment board of the same discharge section.
Working principle of ball mill
The ball mill ball ratio should be judged according to the effective length of the mill, whether it is equipped with roller press, feed size, lining material and structure, and the number of rotation speed. After installing the ball mill, ball mill size gears need to be meshed and the amount of processing is also gradually increasing. After the ball mill has been running normally for two or three days, check the meshing of the large and small gears. Until everything is OK, open the ball mill manhole cover and add the remaining 20% steel balls for the second time.
1.The friction between balls, balls and ore, balls and ball mill liner will increase the wear and tear of ball mill when it is normally operating. So you do not need to add a small ball under normal circumstances.
2.The steel ball in the ball mill are continuously wore during operating. In order to maintain the ball filling rate and the reasonable ratio of the ball, and stable operation of the ball mill, it is necessary to add ball mill balls to compensate for the wear.
3.The weight of the steel ball depends on its quality. While the quality of steel balls determine the capacity of ball mill grinder. The quality of the steel ball is calculated according to the amount of ore processed per ton (ie 0.8kg per ton of ore). The average steel ball needs to process one ton of ore (1kg-1.2kg).
In general, the ratio of ball mill ball is a complicated technical problem. Each concentrator must carefully analyze its actual situation. Through long-term research and accumulation, you can find the right match ratio for yourselves. Besides, the ball ratio also includes the size and quantity of grinding balls.
Ball mill grinder
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