The liner of the wet ball mill mainly plays two roles: one is to protect the cylinder of the ball mill and eliminate the direct friction and impact of materials and steel balls on the cylinder;
The second is to use different types of ball mill liners to adjust the movement state of ball mill steel balls, enhance the crushing effect of steel balls on materials, improve grinding efficiency, increase output, and reduce metal consumption.
At present, the commonly used materials for ball mill linings include high manganese steel linings, wear-resistant rubber linings, medium alloy linings, medium chrome linings, cast stone linings, etc. The three linings are described in detail below.
1. Rubber liner
Advantage
Light weight, low labor intensity for lining installation and short maintenance time;
Light load, lower power consumption, about 10% lower than other types of liners; long service life, prolonging the service life of the barrel and improving the operating rate of the mill;
Save steel balls. If a concentrator with an annual output of 100,000 tons can save about 150,000 tons of steel balls compared with the manganese steel liner;
The industrial noise is low, which improves the working conditions of workers.
Disadvantage
Not suitable for dry grinding, not resistant to high temperature, poor impact resistance, not suitable for coarse grinding chamber of ball mill.
Rubber liners have many advantages and are widely used in ball mills, including cylinder rubber lifting strips, cylinder liners, feed end liners, discharge end grid plates and other ball mill components. Of course, the rubber material of different parts will be different. At present, rubber linings are mainly used in wet grid and wet overflow ball mills.
2. High manganese steel liner
Advantages
High manganese steel liner has certain impact toughness. When impacted, the surface is cold-work hardened, hard and wear-resistant. The hardness can reach HB300-350, and the impact value can reach 700Nm/cm2.
Disadvantages
It is easy to be bent and deformed prematurely during use, and the fixing bolts are pulled off, causing the liner to fall off and reducing its service life. According to statistics, the service life of high manganese steel liners is about 5000-6000 hours.
It is usually used in the first bin of the ball mill – the crushing bin. The particle size of the material in the crushing bin is large, so it is required to mainly impact the grinding body, and the grinding body should be in the throwing state. Therefore, the liner of the crushing bin must have high lifting capacity and good impact resistance to the grinding body. High manganese steel lining is the only option to meet this requirement.
3. High chromium cast iron liner
Advantages
excellent wear resistance and high temperature plasticity, high hardness, small hardness gradient, high tempering stability and corrosion resistance.
Disadvantages
poor impact toughness
High chromium cast iron lining is a lining material after high manganese steel. Compared with other wear-resistant materials, it has high hardness and superior abrasive wear resistance, especially under low load impact. However, due to the high molybdenum content, high price, and limited application, many institutions are working on improving the composition of high chromium cast iron to reduce costs.
At present, besides the above-mentioned three mainstreams, the liners used in ball mills in mineral processing plants also include stone liners, cast stone liners, and mixed liners. But the market is still dominated by high manganese steel, rubber, high chromium cast iron, especially high manganese steel.
