BallMill Diam 43 3D model

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A grinding cylinder rotates within a Ball Mill, launching steel balls that plunge back into the cylinder and collide with the material being ground. The rotation rate typically ranges between 4 to 20 revolutions per minute, dictated by the mill's diameter. As the diameter increases, the rotational speed slows down. Excessive peripheral speed causes the mill to function as a centrifuge, preventing the balls from falling back and forcing them to cling to the outer rim. The point at which the mill begins to operate like a centrifuge is known as the Critical Speed, and ball mills usually run between 65% to 75% of this threshold. Ball Mills are commonly employed to grind materials measuring 1/4 inch or finer, down to particle sizes ranging from 20 to 75 microns. To achieve optimal efficiency with ball mills, they must be operated within a closed system, where oversized material is continuously recirculated back into the mill for further reduction. Various classifiers like screens, spiral classifiers, cyclones, and air classifiers are utilized to classify the discharge from ball mills.