Ball mill used in the process of fining material

 

Ball mill,like hammer crusher, and impact crusher, grinds material through the rotation of a cylinder with steel grinding balls, which cause the balls to fall back into the cylinder and onto the material to be ground. The rotation is usually between 4 to 20 revolutions every minute, depending on the diameter of the mill .The larger the diameter is, the slower the rotation rotates. If the peripheral speed of the mill is too great, it begins to act like a centrifuge and the balls do not fall back, but stay on the perimeter of the mill.  Ball mills usually operate at 65% to 75% of the critical speed.
Ball mill has been used to produce fine particles from a coarse feed for some period of time. Traditional powder metallurgy uses many types of ball mills to produce fine material powders by the pulverization of the starting materials. However, in a traditional ball mill, the energy exchange between the tumbling balls themselves and the powder particles tends to be chaotic.
Chaotic ball motion and insufficient and uncontrolled grinding of the powders characterize this process. In order to obtain a homogeneous and reproducible product, good control of the milling process, particularly control of the ball movement, is essential. To achieve this goal, we research on the development and the characterization of a ball mill for use in mechanical alloying.  The improved ball mill used here has a cylindrical chamber of 12.5 cm in diameter and 8.75 cm wide. It is shown that the control of the ball motion during the milling of limestone leads to a reduction in grinding energy of 40% and a more homogeneous product.
Various classifier5.html">classifiers, for example, screens, spiral classifiers, cyclones and air classifiers are used for classifying the discharge from ball mills. Ball mill is an efficient tool for grinding many materials into fine powder. The ball mill is used to grind many kinds of mine and other materials, or to select the mine. It is widely used in building material, chemical industry, etc. There are two types of grinding: the dry process and the wet process. It can be divided into tabular type and flowing type depending on different forms of discharging material.
Compared with cone crusher or impact crusher,ball mill is generally used to grind material 1/4 inch and finer, down to the particle size of 20 to 75 microns. To achieve a reasonable efficiency with ball mills, they must be operated in a closed system, with oversize material continuously being recirculated back into the mill to be reduced.