How to choose a conventional mill

How to choose a conventional Mill:

In order to distinguish self mills from conventional mills, the mill with mental mediums (Like balls and rods) added are called conventional mills, such as Ball Mills and Rod Mills . They each has different features. How to choose an appropriate mill according to the nature of the ores and material’s size according to the Beneficiation Process? It plays a very important role on getting high grinding efficiency and improving the economical effects of grinding requires. Ball mills and rod mills ore factory always use have following features and applications.

(1)Grate type Ball Mill
Due to the existence of grid plate and elevator bucket in fan chamber, grate mill realizes low-level forced discharge. As a result, fine mineral particles can be discharged in time and qualified particles will not stay too long in the mill, which makes less over-crushing phenomena, faster grinding speed , and higher efficiency.

As the slurry level of the mill is lower and the ores are in smaller quantity, together with the “separation” effect of grating, on the one hand, higher media filling rate can be adopted for increasing ball charge with appropriate amount of small balls; on the other hand, when the ball is lifted to certain height, it has a considerable falling height compared to the lower slurry level. Therefore, the impact effect of media ball is rather strong, which is of excellent crushing and grinding effect.

As the mill is of high discharging speed, the dwelling time of ore is relatively shorter. The grinded ores can be transferred quickly from the mill to Classifier for further opearation, which is helpful for the mill to be compensated with more ores. Meanwhile particles of large size would not dwell long in the mill, which reduces over-crushing and improves productivity. Compared with the overflow type of the same specification, the output capacity is 10%～25% higher. It is applicable to single-stage coarse grinding and the first stage of two-stage grinding, and also the grinding of easily-crushing and soft ores.

(2) Over-flow type ball mill
Over-flow type ball mill discharges because the hollow shaft diameter at discharging side is bigger than that in feeding side, making pulp surface of the mill tilts towards the discharging side. When the position of the pulp is higher than minimum bus of the discharging mouth’s diameter, the pulp will overflow the mill. This is none-forced discharging, so that the discharging speed is low, ores staying long in the mill and media’s effect is unclear. As a result, over-flow type ball mill has serious over-crushing phenomena, and the capacity is lower than the same type grate ball mill. Over - flow type ball mill is suitable for fine grinding or second –period crushing.

(3)Rod mill
The media in rod mill are rod, which will contact ore material after falling down. It has the chose function, that is, the Rod mill can crush materials in turn according to the size----from the big to small. Thus, rod mill has less over crushing and even products. It is suitable for primary crushing or gravity seperating plant requiring little over crushing.