It is well known that newly installed ball mills have a running-in process. During this process, for the first addition of steel balls, the steel balls must account for 80% of the ball mill’s maximum ball loading capacity. The proportion of steel balls added can be based on their size (Φ120mm, Φ100mm, Φ80mm, Φ60mm, Φ40mm).

　　Different ball mill models have different ball loading capacities. For example, the HX1500×3000 ball mill has a maximum ball loading capacity of 9.5-10 tons. For the first addition of steel balls, large balls (120mm and 100mm) should account for 30%-40%, medium balls (80mm) for 40%-30%, and small balls (60mm and 40mm) for 30%.

　　Why is only 80% of the steel ball quantity added during the running-in process? This is likely a point of confusion for many. Experts tell us that after the ball mill is installed, the large and small gears of the ball mill need to mesh, and the processing capacity should also be gradually increased. After the ball mill has run normally and continuously for two to three days, check the meshing of the large and small gears. Once everything is normal, then the ball mill’s manhole cover can be opened for the second addition of the remaining 20% of steel balls. After the ball mill starts running normally, steel balls are added per shift in a ratio of 3:4:3 (120mm for 3, 100mm for 4, 80mm for 3).

　　Here, one point requires attention: small steel balls generally only need to be added during the first ball loading. This is because during normal operation of the ball mill, reasonable friction occurs between steel balls and steel balls, steel balls and ore, and steel balls and the ball mill liners. As wear increases, the steel balls gradually become smaller, and medium balls will turn into small balls. Therefore, under normal circumstances, the ball mill does not need small balls added again except for the first time. Small balls can be added if the useful mineral particles do not have single-body dissociation, and the fineness of the grinding mill does not meet flotation requirements.

　　During the continuous operation of the ball mill, steel balls will continuously wear out. To maintain the ball charge filling rate and a reasonable ball ratio, and to ensure stable operation of the ball mill, reasonable ball replenishment must be carried out to compensate for wear.

　　The weight of added steel balls is based on their quality. The quality of the steel balls determines the addition amount per ton of ore processed. It is best to use new super-hard wear-resistant steel balls. The best steel ball addition is calculated based on the amount of ore processed per ton (i.e., adding 0.8kg per ton of ore). General steel balls require 1kg-1.2kg to process one ton of ore.

　　Different ball mill models also have different ratios. Here, Hebei Gangnuo provides some suggestions for the proportion of steel ball sizes for your reference. For ball mills with a diameter below 2500mm, the recommended steel ball sizes are 100mm, 80mm, 60mm. For ball mills with a diameter above 2500mm, the recommended steel ball sizes are 120mm, 100mm, 80mm.