The reasonable ratio of the ball diameter has two aspects. One is to determine which balls of diameter are installed, and the other is to determine the proportion of balls of various diameters, and the actual mass. In theory, in order to achieve a good grinding effect, it should be ensured that the mass ratio of various balls in the grinding machine is compatible with the particle size composition of the material to be ground. Ball mills in our production sites are equipped with a variety of balls of different sizes to process mixed materials of different sizes.
For new processing plant, due to the lack of actual data, multi-reference similar beneficiation plant plus the actual proportion ball, the production process to make the appropriate adjustments.
The practice of ball blending in the production of the beneficiation mill can be summarized as follows:
(1) First take the whole ore sample of the grinding machine (usually take the new ore and return sand samples separately, then scale the sample) to carry out the sieve analysis and divide into several grain grades, such as 18~12, 12~10,10~ 8,8 to 6, etc., weigh each particle level, calculate the mass percentage (yield) of each particle size, such as 
, ,……Wait;
(2) use the upper limit of each level of granularity (such as 18, 12, 10, 8, etc.) or the upper and lower averages (such as 15, 11, 9, 7, etc.) refer to Table 18 or use the formula to determine each size The diameter of the ball that needs to be added, such as , ......
(3) According to the principle that the mass ratio of the balls of various sizes is compatible with the particle size composition of the grinding material, the percentage of balls of various sizes to the total mass of the ball is determined, correspondingly ' D18 = 18 a 12, ' D12 = 12 a 10, ' D10 = 10 - 8 , ' D8 = 8 - 6 ......"
(4) Adjust the calculation results appropriately. Due to the actual ball, too small balls are not matched, only a few balls are selected. Therefore, the calculated small diameter balls can be proportionally distributed to the larger balls to re-determine the mass percentage of the balls at all levels. D18 , D12 , D10 ......
(5) Calculate the actual quality of the ball at each level, the steps are as follows:
1 Calculate the total mass of the ball by the formula G:
Where G is the total mass of the ball, t;
D——the inner diameter of the barrel of the ball mill, m;
L——the effective length of the barrel of the ball mill, m;
- medium filling rate, %;
- the bulk density of the ball, t/m 3 .
2 Calculate the mass of each level of ball according to the adjusted ball ratio of each level as G D18 =G· D18 , G D12 = G· D12 , G D10 =G· D10 , G D8 = G· D8 ......
[Example] A selected factory 1500mm × 3000mm wet lattice ball mill to load the ball, determine the filling rate =50%, cast steel ball = 4.5t/m 3 , the mill is treated as medium hard ore.
1) The results of the complete ore screening of the grinding machine are shown in Table 1.
Table 1 Total ore screening results
Size (mm) | Yield(%) | Size (mm) | Yield(%) |
18~12 |
| 6 to 4 |
|
12~10 |
| 4~2 |
|
10~8 |
| 2 to 1 |
|
8~6 |
| 1~0 |
|
2) Calculate the ball diameter to be matched according to the upper limit of each level and round up, see Table 2.
Table 2 should be equipped with the size of the ball diameter
Size (mm) | Ball diameter (mm) | Size (mm) | Ball diameter (mm) |
18~12 | D 18 =120 | 6 to 4 | D 6 =70 |
12~10 | D 12 =100 | 4~2 | D 4 = 60 |
10~8 | D 10 =90 | 2 to 1 | D 2 = 50 |
8~6 | D 8 =80 | 1~0 | D 1 =40 |
3) The mass percentage of various balls is shown in Table 21.
Table 21 Percentage of mass of various balls
Ball diameter (mm) | Quality ratio (%) | Ball diameter (mm) | Quality ratio (%) |
120 | 20 | 70 | 5 |
100 | 40 | 60 | 4 |
90 | 15 | 50 | 4 |
80 | 8 | 40 | 4 |
If it is determined that only 120, 100, 80, and 60 balls are added, the ratio of 90, 70, 50, and 40 balls can be appropriately adjusted to other balls. The results of this example are shown in Table 3.
Table 3 Percentage of mass of various balls after adjustment
Ball diameter (mm) | Quality ratio (%) | Ball diameter (mm) | Quality ratio (%) |
120 | 30 | 80 | 13 |
100 | 45 | 60 | 12 |
4) Calculate the total mass G of the added ball:
5) Calculate the quality of each ball should be added separately
G 120 =G· 120 = 11.928 × 0.3 = 3.58 (t)
G 100 =G· 100 = 11.928 × 0.45 = 5.37 (t)
G 80 =G· 80 = 11.928 × 0.13 = 1.55 (t)
G 60 =G· 60 = 11.928 × 0.12 = 1.43 (t)
6) According to the calculation result, the ball is weighed.
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