How to choose liner and grinding balls for ball mill

For a long time, an incorrect statement has been widely circulated, that is, the hardness of the grinding ball is HRC3-5 higher than that of the lining plate. Ask for the reason, but there is no place to verify it.

The lining plate and grinding ball are undoubtedly interdependent, forming a three body abrasive wear together with the material. But what exactly is good? It should be said that the concept of "base hole system" or "base axis system" in mechanical design is borrowed to understand * *. As for ball mills, the impact of liners on production is much greater than that of grinding balls, so it should be a "substrate system". Therefore, in the selection of lining plates and grinding balls, the first thing to decide is the lining plate, which must ensure that the service life of the lining plate is at least two major maintenance periods, and should not be repaired as much as possible. Prioritize selecting lining plates with good reliability and high wear resistance. For example, with the combination of self consolidating high chromium cast iron lining plates, the service life of coal mills in power plants can reach 20 years, and the service life of cement mills can reach 10 years, with almost no maintenance required.

The service life of alloy steel lining plates in dual medium quenching is over 8 years for coal mills in power plants, about 3 years for cement mills, and about 10 months for iron mines. Even dual medium quenched low chromium alloy steel liners can have a lifespan of over 6 years in power plant coal mills, around 2 years in cement mills, and over 8 months in iron ore mills.

The hardness of the lining plate and grinding ball should be above HRC50, mainly because the hardness of the hard phase in the abrasive is 6-7 Mohs hardness, estimated to be close to HRC60. Theoretically, the hardness of the grinding medium should be greater than or equal to 80% of the abrasive hardness to have ideal anti-wear effect.

After the lining plate is determined, it is easy to choose the grinding ball. As long as the service life of the lining plate ensures two major maintenance periods, the priority should be given to advocating the wear resistance of the grinding ball. If both the lining plate and grinding ball can be kept unchanged for 10 years, that would certainly be ideal. One principle: reduce costs, alleviate labor intensity of workers, and improve the operation rate of ball mills.

Under the premise of "substrate system", it is allowed for the grinding ball to have a hardness HRC3-5 higher than that of the lining plate, which is fundamentally different from the circulating concept for the high manganese steel lining plate that should be eliminated.

Choose grinding ball strategy

1. Both high manganese steel material and traditional ball mill lining plate form are not suitable. The groundbreaking design of the combination of self fixing lining plates has great advantages, completely solving the problems of broken bolts and powder leakage, and reducing maintenance by more than 98%; Composite lining plates can fully utilize the quenching hardness of various high hardness materials, enabling them to exhibit ideal wear resistance.

In the dry process, power plants and cement plants should prioritize the use of dual medium quenched medium and low chromium alloy steel liners or high chromium cast iron and high chromium cast steel liners, and choose high hardness high chromium cast iron grinding balls. Dual medium quenching of medium and low chromium alloy steel has good economic benefits; In the wet mining process, from an economic perspective, high and medium carbon alloy steel liners or Cr10~Cr20 series cast iron liners with low carbon content and high hardness low chromium alloy grinding balls are preferred. But for grinding balls with a diameter greater than 110mm, high carbon alloy steel forging balls should be considered.

3. The matching between the lining plate and the grinding ball should be based on the perspective of "substrate manufacturing". Under the premise of ensuring two major maintenance periods for the service life of the lining plate, the best anti-wear performance of the grinding ball should be selected. The hardness of the lining plate should be greater than HRC50, the hardness of chromium molybdenum alloy cast grinding balls should be greater than HRC52, and the hardness of forged alloy steel grinding balls should be greater than HRC55. Generally, choose the grinding ball with the best anti-wear performance as much as possible.