Influence Factors of the Ball Mill in the Process of Grinding
Beneficiation ball mill has three influence factors in the grinding process with medium, including the ore properties, the structure of and the operation conditions of the machines.
1.The Ore Properties
(1) the grindability of the ore. The harder of the ore, the smaller of the grindability, thus lower the productivities of the machine.
(2) the granularity of the feeding ore and the product. The Coarser the granularity of the feeding ore, the longer time will be the machine take to grind the ore to specified fineness, thus lower the productivities of the machine.
2.the Structure of the Ball Mill
(1) The type of the machine. The grid ball mill has heavy productivity, and lighter over-crushing, while coarse granularity of the ore, thus is not fittable to fine grinding. The productivity of the overflow ball mill lower about 10 to 15 percent of the grid ball mill of same type . But over-crushing problem is serious to the overflow machine, while the granularity is small .
(2) The size of the machine. The size of the machine means the diameter and the length of the cylinder. The length of the cylinder decides the remain time of the ore in the cylinder. Longer of the cylinder, more serious of the grinding. While if the length is not enough, target fineness maybe not being reached. The diameter property of the ball mill usually get 1-1.5.
3.Operating Conditions of the Ball Mill
(1) the rate of the rotate and the filling. When the filling rate is 30% to 50%, and the rotate rate is 40% to 80%, the useful rate of the machine will increase with the increase of the rotate rate. Thus when the rotate rate gets to a proper number, the productivity of the ball mill will get the top rate as well as the filling rate reaching 40% to 50%.
(2)the shape and size of the ball mill. Except steel ball and steel bar, the shape of the grinding medium also includes steel short column and steel column ball,which have more effect than the steel ball and bar. Thus some iron dressing plant have adopted abnormity grinding medium instead of steel ball in the second section of milling operation.
(3) the density of the pulp and the speed of the feeding ore. Pulp density has its best range. The feeding speed should be equality and continuity. If not, such as too little feeding ore, which will excess the wear of the machine. On the contrary, bulging belly will happens and stop production when necessary.
(4) Cyclic load. Typically,the appropriate value of the cyclic load id 150% to 600%.
