Discussion on the error area and its influence in judging the quality of Ball Mill
The quality of ball mill not only influences productivity, but also affects the ball consumption, and then influences the cost of grinding media. The pure pursuit of high hardness and low unit consumption is not right. High hardness and low unit consumption are not equal to low cost, high hardness and low unit consumption ball is often very high price. High hardness does not necessarily make the productivity increase or even decline, and only high productivity can cause the unit consumption index to decline. Therefore, the choice of steel ball should be the primary standard mill productivity, and grinding media cost is low. Only high productivity and low cost of grinding media can have good economic benefits. The economic benefit is the necessary condition for the existence and development of enterprises.
When choosing steel ball, two problems are often ignored: the harder the steel ball is, the better, but has its appropriate hardness value; the steel ball density is also a problem that can not be ignored. With respect to the effect of hardness, generally speaking, as the hardness increases, the unit consumption of the steel ball decreases as long as the crushing does not take place; moreover, the ball deforms less, the ball deforms less in crushing, and the energy can be used more for crushing the ore particles Can increase the productivity of the mill. However, the increase in the hardness of steel ball can only be moderate; there is an appropriate range, not the harder, the better. If only ball wear is taken into account, the higher the hardness, the lower the wear. However, for the mill productivity, the productivity increases with the increase of the hardness of the steel ball in a certain range, but when the hardness exceeds a certain range, the productivity of the mill is adversely affected, and the productivity of the mill is decreased. When the hardness of the steel ball is too high, it is disadvantageous to grinding for two reasons:
1)The spring back of steel ball is serious, causing part of energy loss in the spring back, so the energy of steel ball is not more used for crushing, so impact crushing;
2) When the hardness of the steel ball is too high, the ball and the ball slide badly when they contact each other, which can not effectively engage the ore particles between the balls and weaken the grinding action of the ore particles.
As to the effect of ball density on grinding, in general, the same size of ball density of large productivity, the small density of small productivity.
The ball density is affected by three factors:
(1) The density of steel is higher than that of cast iron. The density of alloy steel is different according to the density and content of the main alloy elements.
(2) because of the influence of the manufacturing method of steel balls, the rolled and forged steel balls have a compact structure, so their density is high, and the cast steel balls, cast iron balls or cast alloy balls, etc.
(3) The effect of Martensite, austenite, Bainite, and ferrite on the microstructure of steel ball is different, and the crystal fineness is also affected.