Why does the capacity of ball mill can’t reach the design requirement?

Why does the capacity of ball mill can’t reach the design requirement?
Ball mill is the key equipment for grinding after the crushing process, which is widely used in the manufacture industries, such as cement, silicate, new building material, refractory material, fertilizer, ferrous metal, nonferrous metal etc. Sometimes the capacity of ball mill can’t reach the design requirement, some reasons are below:
1. The larger feed size makes the ball mill need to crush the material again, which reduces the hourly production capacity.
2. The unreasonable length ratio of each bin will cause the imbalance of rough grinding and fine grinding capacity, which will reduce the capacity.
3. The raw material is higher water content, which is stuck in the ball mill and can’t be discharged in time, so that reduce the capacity.
4. The ratio of raw materials is unreasonable with each bin
5. The higher temperature of raw material will reduce the grinding efficiency and reduce the capacity.
6. The raw material is hard.