Length diameter ratio and bin division of ball mill

What is the aspect ratio and bin division of the ball mill mentioned everyday? Today, Fodamon engineer analyze the following. According to the principle of grinding dynamics, the grinding operation of materials is gradually completed in the mill, and a certain grinding time is required. If the flow rate of material in the mill is stable in the equilibrium state, the grinding time can be calculated from the length of the mill.

Due to the difference in particle reduction and work done by materials in the mill, if the open flow mill passes through once, it must meet the fineness requirements of finished products, so it needs a long grinding time, so the mill needs a long time. The circular flow mill passes through the mill for many times, and the fineness of the finished product is controlled by the powder concentrator. The fineness of the materials out of the mill will change with the circulating load. If the fineness is coarse, the mill can be relatively shortened. Another example is grinding raw meal and grinding cement. Because the fineness of finished products is different and the grinding resistance is different, the grinding time is also different, and the length of the mill can also be different.

However, due to the complexity of the grinding process and many influencing factors, it is difficult to calculate the appropriate length theoretically. Generally, it can only be determined by applying statistical methods according to experience.

In addition, the material flow velocity in the mill is also affected by many factors, such as compartment form, filling rate, ball grading, ball diameter, material performance and so on. Therefore, even if the length is the same, the grinding time in the mill is not the same. In other words, the grinding length can also be changed appropriately for the same grinding time. But the difference should not be too great.

The output of the mill is directly proportional to d2.5l. To expand the mill capacity, first increase the diameter. If l is basically unchanged, L / D will decrease with the increase of mill capacity, that is, with the increase of mill diameter. Therefore, the L / D of large mills is much smaller than that of small mills in the past. Of course, the L / D of a certain diameter mill is not a constant, but can change within a certain range, and its output will change accordingly. That is, the mill with the same diameter can have several lengths to meet the requirements of different output.

The basic trend of the relationship between length diameter ratio and diameter of the mill is that l / D decreases with the increase of D, while L / D fluctuation of the same diameter can reach 0.5-1.0. Moreover, the L / D values of different types of mills are also different. Even if the same type, such as circulating water mud mill, is designed in different countries.

For wet rod mill, since the length of rod bin must be greater than 1.1-1.2 times the diameter, the grinding capacity of rod bin accounts for about 1 / 4 of the total grinding capacity. Therefore, the L / D of the whole mill, no matter how large the diameter, must be greater than 4.4-5.0.

The bin division of the mill varies with the type of mill, grinding mode, length diameter ratio and other factors. The proportion of each bin is more affected by feed particle size, grindability and outlet grinding fineness. In fact, the proportion of each warehouse often changes in production. Therefore, the mill design should meet this need, the compartment device should be able to move accordingly, and the grinding door position should also adapt to the change of bin position.

The open flow mill is generally divided into 3 bins. Bin 1 is coarse grinding bin, bin 2 is transition bin, and bin 3 is fine grinding bin. There are also four silos, that is, the fine grinding silo is divided into three silos and four silos.

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