Ball Mills » Cylindrical Ball Mill
Cylindrical Ball Mill
Ball mill is an efficient tool for grinding
materials like ores, chemicals, ceramic raw materials, paints etc. into fine
powder or fine paste by grinding in a wet way. The Ball Mill operates by
rotating a cylinder with grinding balls like steel, CI, ceramic and pebble
balls as grinding media.
Material fed through the mill is crushed by impact and grounded by
attrition between the balls and also the internal cascading effect reduces
the material in to a fine powder.
Ball Mills usually have liners inside which are replaceable when they wear.
Liners will be of wave shape which key the ball charge in to the shell and
prevent the slippage.
The rotation of the powder mixer is usually between
4 to 20 revolutions per minute, depending upon the diameter of the mill. The
larger the diameter is, the slower the rotation will be. Ball Mills are
generally used to grind material ¼" and finer, down to the
particle size of 20 - 75 microns. To achieve reasonable efficiency, the ball
mills are to be operated in a closed system, with oversize particles
continuously being re-circulated back to the mill and to be reduced.
Cylindrical Single / Multi compartment with classifier and without
Single / Multiple Compartments Cylindrical Ball Mill
Single compartment Mill is a conventional type of
batch mill, consists of cylindrical steel shell with flat steel ends welded
to shell. Ball Mill rotates around a horizontal axis partially filled with
raw materials to be ground plus the grinding medium. The material and the
grinding medium are fed and discharged through an opening manhole on the
cylinder shell. Ball Mills usually have replaceable liners inside and
replaced when they wear out. Material fed through the mill is crushed by
impact and grounded through attrition between the balls.
The horizontal cylinder of the ball mill, which is fabricated out of mild
steel plates, is rotated using a side drive system at one end of the mill.
The drive comprises of a girth gear, generally made from alloy steel
casting, bolted onto the mill which is driven by its pinion, generally made
out of alloy steel forging, through a gear reducer and motor coupled
The two ends of the cylinder are covered with mill headers one placed at
each end, the inlet and at the discharge. The mill headers have a central
inlet and discharge opening from where the material enters the mill and
exits the mill. These mill headers are generally made out of alloy steel
casting. The mill headers are rested on fabricated trunions at both ends on
which the headers rotate on a special self lubricating white metal lining.
External lubrication system is also provided to keep the mill headers
properly lubricated at all times. Other accessories include a set of low
pressure and high pressure pumps which help to pre-jack the mill during
A ball mill is partly filled with steel balls (some
are cylindrical shaped cylpebs) that impart a tumbling and cascading action
when the mill rotates around its horizontal axis. Material fed through the
mill is crushed by impact and ground by attrition between the balls. The
grinding media are usually made of high-chromium steel or manganese steel.
The smaller grades are generally cylpebs.
Mill liners are generally of high chromium steel or
manganese steel. The liners are selected based on the type and hardness of
the material to be ground. The grinding media is also selected with the same
principal and suitable to the material of the liners. The thickness and
design of the liners largely effect the grinding efficiency of the mill and
hence various improvements in the designs have been made from time to time.
|Size Dia x L, ft
||Max. Ball Load lb.
<200 - m To
95% < 325 -
m bbl / hr. (a)
<12.m to 95%
< 100m t.p.h. (b)
Gypsum to 95%,
100m t.p.h. (c)
|4 x 10
||28 to 30
|4 x 18
||28 to 30
|5 x 22
||25 to 27
|6 x 24
||22 to 24
|7 x 26
||20 to 22
|8 x 30
||18 to 20
|9 x 30
||16 to 18
|10 x 30
||15 to 17
- Closed-circuit with air classifier. Product size equivalent to 1.750
to 1.800 cm²/gm
- Open circuit ; moisture less than 0.5%, average grind ability
- Feed temperature , 200° to 300°F - Open circuit operation