


How
Ball Mill work?





Ball mill is a grinder for
reducing hard materials to powder. A ball mill
grinds material by rotating a cylinder with steel
grinding balls/ceramic balls causing the balls
to fall back into the cylinder and onto the material
to be ground.
The cylinder rotates at a
relatively slow speed, allowing the balls to cascade
through the mill base, thus grinding or dispersing
the materials. The rotation is usually between
4 to 20 revolutions per minute, depending upon
the diameter of the mill. The larger the diameter,
the slower the rotation.



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. The point
where the mill becomes a centrifuge is called the "Critical
Speed", and ball mills usually operate at 65% to
75% of the critical speed. 

Ball mills are 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. Various classifiers, such
as screens, cyclones and air classifiers are used for
classifying the discharge from ball mills. 






Based on operation, ball mills are classified into batch
mill and continuous mills , they are also classified depending
on the type of grinding media used namely steel ball mill, pebble
mill, jar mill ( for lab and R&D purpose) 



