How the Batch Process Works
The operation of a batch size production mill is simple and effective. The material to be ground and the grinding media are placed in a stationary, jacketed tank. This media is spheres 3/32" to 3/8" diameter. Commonly used types are carbon steel, stainless steel, chrome steel, tungsten carbide, ceramic, or zirconium oxide.
The material and the media are then agitated by a shaft with arms, rotating at high speed. This causes the media to exert both shearing and impact forces on the material, resulting in optimum size reduction and dispersion.
No premixing is necessary. The material can be directly fed into the jacketed grinding tank of the mill. Those portions of the formulation requiring only slight grinding can be easily added later.
The mills are equipped with specially designed high starting torque, two-speed electric motors. The high starting motor means no clutches, etc. are needed. The lower speed is used for charging and discharging and the high speed is used for grinding. Depending upon the application, electricals can be T.E.F.C. (totally enclosed fan cooled) or explosion-proof.
Production batch mills are equipped with a built-in pumping system that maintains circulation during grinding for accelerated attrition and uniformity. This pump can also be used for material discharging. The final result of the grinding action is a fine, even particle dispersion.
Temperature control (either cooling or heating) can be maintained due to the use of jacketed tanks. When high-pressure water, coolant, oil or steam systems are required, A.S.M.E.-coded tank jackets may be employed. Because grinding action does not take place against the tank walls, wear of the walls is minimal. In addition, thinner walled tanks mean that improved heat transfer can be accomplished.