The influence factors of ball mill working efficiency are approximately proportional, some nonlinear, some relevant, and such factors as matching filling ratio of grinding media will change along with the implementation of the grinding process and the loss of grinding media.

　　For this reason, it is very difficult to precisely and scientifically calculate the influence relation of every factor. However, there is one influencing factor which is the most direct, clear and most efficient, feeding granularity.

　　Working efficiency refers to the working amount finished in unit time. For this reason, grinding efficiency refers to the amount of products meeting the granularity requirement of grinding mills in unit time. When the grinding plant, grinding balls and grinding density are the same, the grinding efficiency is mainly related to feeding granularity.

　　Ball mills are used for processing large materials to products with the required granularity, so that if the granularity of feeding materials is similar to that of required, the working load of grinding mills will be smaller and the working efficiency will be higher.

　　According to our calculation, when reducing the feeding granularity from 20mm to 5mm, the relative productivity of grinding mills will be improved by about 30%, which means that the ball grinding mill can process 30% more ores in unit time.

　　When such cost as energy consumption and personnel is certain, if 30% more concentrate products can be got in ore beneficiation plant, the increase in economic benefits for the ore beneficiation plant will be huge, for this reason, reducing the feeding granularity is the most efficiency way of improving the grinding efficiency of ball mill and increasing the benefits of ore processing plant.