Ball mills are suitable for grinding various ores and other materials, and are widely used in mineral processing, building materials and chemical industries. They can be divided into dry and wet grinding methods. According to different ore discharge methods, it can be divided into grid type and overflow type.
Selection of ball size of ball mill
To improve the stability of ball mill operation and grinding efficiency, balls should be loaded and replenished reasonably. How to determine the appropriate size of balls, especially the size of the largest ball and the smallest ball when the ball is first loaded, It will play a decisive role in reasonable ball loading and improving grinding efficiency. Grinding practice shows that when there are mixed media of different sizes in the mill, the grinding effect is better than that of single-sized media. Many experts and scholars at home and abroad have done a lot of research on the reasonable ball loading of the mill and believe that to make the ball mill work with high efficiency, there should not only be a sufficient number of large balls for grinding coarse materials in the ball charge, but also Grinding medium and small balls of fine-grained materials.
The purpose of reasonable ball loading is to keep the proportion of large balls, medium balls and small balls in the ball charge. In a ball mill with a constant rotational speed and ball filling rate, the grinding action mainly depends on the position of the balls in the mill and the type, size and proportion (gradation) of the balls. In the running ball mill, the grinding balls are distributed according to a certain rule, that is, along the axial direction, from the ore feeding end to the ore discharging end, the ball diameter gradually decreases.
Therefore, in the running ball mill, the coarse ore particles will be crushed first, that is, the large balls mainly pulverize the coarse ore particles by impact and crushing; while the small balls mainly grind the fine ore particles by grinding and hitting times , forming a state where big balls beat big grains and small balls grind small grains. Therefore, for a given ball mill and a certain ball load, if the large balls are too large, the number of balls is small, the total surface area of the ball load is small, the probability of hitting ore particles is small, and the material yield of medium particle grade is large, then Conversely, if the balls are too small and the number of balls is large, the surface area of the total ball charge will increase, but the coarse ore particles will not be ground finely, and the yield of fine grade materials will not be great. It will increase the crushing, resulting in the so-called under-grinding and over-grinding phenomenon.
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