Ores from the stope contain a great deal of ore powder produced during drilling and blasting; in the process of crushing, screening, dry grinding, drying and even transporting, a lot of dust is going to be produced. Dispersion and suspension of the dust particles not only impinge on the sanitation, result in the devices’ abrasion and the loss of the useful ores, but also do harm to workmen’s health. Meanwhile, the chemical properties and the content in the air of the dust determine its damage degree to the human beings. Usually the concentrators produce minor siliceous ore dust. The ore content can reach 1600mg/ 3m.
The characteristics of motion of the grinding media in the barrel and its lifting height as well as the trajectory primarily decide the dry mill’s rotation speed and the movement of the grinding media when the mill is in three rotation type. When the speed is low, the lifting height of the grinding media is lower.
The dust catcher is needed to separate the air and dust in the dusty gas. There are cyclone dust collector, foam dust collector, bag dust collector and electrostatic dust collector. The cyclone dust collector is a container whose upper is cylindrical and the bottom is conical. The dusty gas is transmitted into the container at the speed of 20 to 30 meters along the tangent direction of the duct. The airstream does a spiral rotary motion within the container.
If the medium is a steel ball, it is called ball mill; the medium is steel rod, it is called rod mill; the medium is gravel, it is called flint mill. The specification of the mill is represented as diameter×length. When the grinding machine is in rotation, the eccentric force in the rotation of the grinding medium in the cylinder generates certain frictional force between the barrel and itself. The frictional force gets the grinding medium to rotate with the cylinder and reach a certain height. When its gravity exceeds the eccentric force, the medium is about to projectile from the barrel, thus crushing the ores. At the same time, there’s slippage of the grinding medium during rotation that also produces a grinding effect. Therefore, ores are smashed under the combined effects of the impact and grinding force produced by the grinding medium.
