The ball mill's low grinding efficiency, low processing capacity, high production energy consumption, and unstable product fineness are problems that most concentrators will encounter. How to effectively improve the grinding efficiency of the ball mill is an important issue. Below, let's share 10 ways to improve the grinding efficiency of the ball mill!
1.Change the grindability of the ore
The hardness, toughness, dissociation and structural defects of the ore determine the difficulty of grinding. If the grinding degree is small, the ore is easy to grind, the wear of the mill liner and the steel ball is smaller, and the energy consumption is also small; on the contrary, the opposite is true. The nature of the ore directly affects the productivity of the mill.
In production, if it is difficult to grind ore or ore requires fine grinding, it may be considered to adopt a new treatment process to change the ore grindability under economic and site conditions:
One method is to add certain chemicals during the grinding process to improve the grinding effect and increase the grinding efficiency;
Another method is to change the grindability of the ore, for example, to heat each mineral in the ore, change the mechanical properties of the whole ore, and reduce the hardness.
2.More crushing and less grinding, reducing the grinding grain size
If the grinding grain size is large, the grinding machine needs to do more work on the ore. To achieve the specified grinding fineness, the workload of the ball mill is bound to increase, and accordingly, the energy consumption and power consumption will increase.
In order to reduce the feed size of the grinding, it is required that the particle size of the crushed product is small, that is, it is required to be "grinding less and less grinding". Moreover, the efficiency of crushed ore is significantly higher than that of grinding, and the energy consumption of crushed ore is lower, about 12% to 25% of the energy consumption of grinding.
3.Reasonable filling rate
When the rotation speed of the ball mill is constant, the filling rate is large, the steel ball hits the material more times, the grinding area is large, the grinding effect is strong, but the power consumption is also large, and the filling rate is too high, and the movement state of the steel ball is easy. A change occurs to reduce the impact on large particle materials. On the contrary, the filling rate is too small and the grinding effect is weak.
At present, many mines have a filling rate of 45% to 50%. Strictly speaking, it is not necessarily reasonable. Because the actual conditions of each plant are different, it is impossible to achieve the ideal grinding effect by copying the data of others. It depends on the situation.
4.Reasonable steel ball size and ratio
Since the steel ball in the ball mill is in contact with the ore and the ball diameter is too large, the crushing force is also large, causing the ore to break along the penetrating force direction, instead of breaking along the interface of different mineral crystals with weak bonding force. Grinding purposes.
In addition, when the ball filling rate is the same, the ball diameter is too large, resulting in too few steel balls, low breaking probability, excessive pulverization, and uneven product grain size. The steel ball is too small, the crushing force on the ore is small, and the grinding efficiency is low. Therefore, the precise steel ball size and its ratio have an important influence on the grinding efficiency.
5.Accurate supplemental ball
Due to the grinding effect of the steel ball and the ore in the production, the wear of the steel ball will be caused, resulting in a change in the proportion of the steel balls of various sizes, affecting the grinding process and causing the fineness of the grinding product, so a reasonable steel ball repair is required. Adding a system can stabilize production.
6.Reasonable and appropriate grinding concentration
The concentration of the grinding concentration affects the specific gravity of the slurry, the degree of adhesion of the ore particles around the steel ball, and the fluidity of the slurry.
The grinding concentration is low, the slurry flow is fast, the adhesion of the material around the steel ball is low, the impact and grinding effect of the steel ball on the material is weak, the grain size of the ore is unqualified, and the grinding efficiency is not exerted;
The grinding concentration is high, the adhesion of the material around the steel ball is good, the impact and grinding effect of the steel ball on the material are good, but the slurry flow is slow, which is easy to cause the material to be pulverized, which is not conducive to improving the processing capacity of the mill.
In the production practice, the grinding concentration is often controlled by controlling the amount of ore supplied to the mill, or the amount of replenishment water of the mill, or adjusting the classification function, controlling the particle size composition and moisture in the graded return sand.
7.Optimize the grinding process
In actual production, the grinding process can be optimized for the ore properties of the ore, such as the size of the embedded mineral, the degree of monomer dissociation, and the size of the gangue mineral. Such as pre-tailing, pre-enrichment, stage grinding, pre-grading and other operations to optimize the grinding system, on the one hand to reduce the amount of grinding, on the one hand, early recovery of useful minerals.
8.Improve grading efficiency
The effect of grading efficiency on grinding efficiency is self-evident. The high classification efficiency means that the qualified fraction can be discharged in a timely and efficient manner, and the low classification efficiency means that most of the qualified granular products are not discharged and returned to the mill for re-grinding, which is easy to cause over-grinding, thus affecting the later sorting effect. .
The classification efficiency can be improved by using two-stage classification or improved classification equipment.
9.Appropriately increase the graded return sand ratio
The sand return ratio is the ratio of the amount of sand returned by the ball mill to the amount of ore fed, which directly affects the mill productivity. One way to increase the ratio of returning sand to the plant is to increase the original ore supply. Another way is to reduce the shaft height of the spiral classifier.
However, there is a limit to the improvement of the sand return ratio. When the value is increased to a certain value, the increase rate of the mill productivity is small, and the total amount of the mill is close to the maximum processing capacity of the mill, which is easy to cause the belly to rise, so the return sand ratio should not be too large.
10.Automatic control of grinding systems
There are many variable parameters in the grinding operation. One change will inevitably lead to the successive changes of many factors. If the artificial operation control will inevitably lead to the instability of production, the automatic control of the grinding operation can keep the grinding classification stable and suitable. The state of the mine can also improve the grinding efficiency.
According to foreign reports, the automatic control of the grinding graded loop can increase the production capacity by 2.5%~10%, and the treatment of one ton of ore can save electricity consumption by 0.4~1.4kWh/t.
In the grinding process, there are many factors affecting the grinding efficiency. Many factors can only be qualitatively analyzed and judged, and it is difficult to make quantitative analysis. This requires a comprehensive analysis based on the actual production situation and qualitative analysis results. The reasonable parameters are instructed to guide on-site production to reduce production costs and achieve energy conservation and consumption reduction.