When the speed of the mill and the filling rate are certain, that is, when the ball-charge movement state is certain, the size of the steel ball seriously affects the grain size characteristic, the dissociation degree and the consumption index of the grinding ore, and there are 6 main points as follows:

(1) affect the mill productivity size, the ball diameter is too large, because the number of blows less and the grinding area is small, the production rate is reduced, the ball diameter is too low due to the impact of the lack of force to reduce production rate. The precision of the ball diameter can greatly improve the production rate of grinding machine. The author has proved in the industrial test of several concentrator that the ball diameter is changed from too big to accurate, the mill presses -0. The utilization coefficient value of 074mm meter can improve 15%~40%.

(2) The uniformity of grain size distribution of grinding minerals is affected. Too large diameter of the ball to reduce the number of blows, resulting in a large number of coarse grinding, too much of the strike force in the fight against the increase in crushing. Therefore, after the large diameter of the product size is uneven, too thick and crushing of the more, to choose the unfavorable. The author's several industrial tests have proved that the ball diameter from the major to the precision, the grinding of mineral products, the maximum size and average granularity are reduced, and the crushing also reduces $number, product granularity is more uniform, intermediate easy to choose the size of the increase in the mineral processing more favorable.

(3) Affecting the dissociation degree of mineral monomer in grinding minerals. Too large diameter of the ball due to the impact of excessive force of the ore produced through the crushing, only the granularity of mechanical thin, mineral monomer dissociation degree is not high. The probability of mineral dissociation is increased with the precision of spherical diameter, and the dissociation degree of the mineral monomer in the product is improved. The author's industrial experiments show that the precision of the spherical diameter can improve the $number of the monomer dissociation degree of the useful minerals and improve the concentrate grade and recovery rate.

(4) affect the height of the ball consumption. According to Davis's theory of Steel ball wear, the ball wear speed is proportional to its weight, large ball wear speed, large consumption, small ball wear speed, low consumption. This has already been summarized in the Beneficiation Handbook for a. F. Tagarte. The author's industrial experiment also proves this point. Some industrial tests have proved that the ball diameter is adjusted to be accurate, the steel ball single consumption can reduce the $number.

(5) affect the level of electricity consumption. When the load of the ball is constant, the power consumption of the pellets is lower than the big balls.

(6) The size of the grinding machine's noise is affected. Big Ball because of the energy of large, mutual impact or hit the liner when the sound energy loss is also large, so the noise is large. The accuracy of the ball diameter can reduce the noise, through the author's many industrial tests proved that the diameter of the ball is adjusted to be accurate, the mill work noise can be reduced 3~4db. From the above, the size of the steel ball has great influence on the parameters of the grinding, and it is of great significance to select the size of the steel ball accurately.