Ball mill machine

The ball miller machine is a tumbling mill that uses steel milling balls as the grinding media, applied in either primary grinding or secondary grinding applications.

1. Ball Mill Machine
Industrial pharmacy
نيكراشملا ءامسأ
ناكرأ رون ةدوج دمحا
نامحر الله ةبه راكع دمحم
نيدلا دامع دمحا

2. :Contents
Introduction
Principle
Components
Working
Applications &Uses
Advantages
Disadvantages

3. Introduction
Size reduction is the operation carried out for reducing
the size of bigger particles into smaller one of desired size
and shape with the help of external forces.

Objectives of Size Reduction:
To produce smaller particles (in the preparation of
suspensions or to facilitate the mixing of powders).
To increase surface area (to increase adsorptive
properties).
In drugs that are crushed to expose cells prior to
extraction.
Reduce the bulk of a material, since shipping charges
may be based on volume.

4. A ball mill is a type of grinder used to grind, blend and
sometimes for mixing of materials for use in mineral dressing
processes, paints, pyrotechnics, ceramics and selective laser
sintering.
It is efficient tool for grinding many materials into fine powder.
A ball mill consists of a hollow cylindrical shell rotating about
its axis.
The axis of the shell may be either horizontal or at a small
angle to the horizontal.
It is partially filled with balls.



Most ball mills are batch operated,
however there are continuous ball millers
available nowadays with continuous milling
action.

5. The grinding media are the balls, which may be
made of steel (chrome steel), stainless steel, ceramic
or rubber.
The inner surface of the cylindrical shell is usually
lined with an abrasion-resistant material such as
manganese steel or rubber lining.
Less wear takes place in rubber lined mills.
The length of the mill is approximately equal to its
diameter.

6. The ball mill can be divided into wet ball mill and dry ball mill according
to the use environment.
The difference is that the structure of the dry ball mill is more
complicated than that of the wet ball mill. The discharge port of the dry
ball mill is straight and equipped with an air induction device, a dust
exhaust pipe and a dust collector. The structure of the wet ball mill is
relatively simple, there is no need to add too many auxiliary
accessories, the discharge port is flared, and the built-in spiral device is
more convenient for ore discharge.
The wet ball mill has better performance, higher grinding efficiency,
and lower requirements for the moisture content of the ore. In
addition, its auxiliary equipment is less and the material transportation
device is simple. Therefore, the investment is about 5% -10% lower
than that of the dry ball mill.

7. 1) Horizontal Ball Mill
Are the most common type in the industry.
Some horizontal ball mills have the timers to view
the processed materials contained in it.
Some have timers, to check the materials within
the time period.

2) Industrial Ball Mill
Larger in size than the other types.
Size varies from the size of a refrigerator to the
bus.
The main difference is the number of chambers.
Another difference is its forced-air system.

3) Planetary Ball Mill
These are most commonly used for laboratory use.
Used for small applications, and fits in lab table or
workbenches.
Different ball sizes for different uses.
Types of Ball Mills:

8. The degree of milling in a ball mill is influenced by:
1)Residence time of the material in the mill chamber.
2)The size, density and number of the balls.
3)The nature of the balls (hardness of the grinding
material).
4)Feed rate and feed level in the vessel.
5)Rotation speed of the cylinder.

9. Factors influencing the size of the product in the ball mill:
1)The rate of feed: with a high feed rate, less size
reduction is effected since in this case the material is in
the mill for a shorter time.
2)Weight of balls: with a heavy discharge of balls, we
get a fine product. we can increase the weight of the
charge by increasing the number of balls or by using a
ball material of high density.
3)The diameter of the balls
4)The slope of the mill
5)Discharge freedom
6)The speed and rotation of Ball mill

10. Principle
A ball mill works on the principle of impact and
attrition.
size reduction is done by impact as the balls drop
from near the top of the shell.
Ball mills rotate around a horizontal axis, partially
filled with the material to be refined plus the grinding
medium. An internal cascading effect reduces the
material to a fine powder.

11. Components
ball mill grinding machine consists of following parts:
A.Feeding part
B.Discharging part
C.Turning and driving part( gear, motor.. etc)
D.Rotating balls

12. Ball mills consist of the following components:

A.Inlet – crushed ore is fed to the ball mill through the inlet.
A scoop ensures the feed to the mill is constant.
B.Discharge – reduced feed exits the mill through the
discharge.

13. C. Drum – the drum is the cylindrical casing of the ball mill.
The inside of the drum is fitted with manganese steel alloy
plates (‘armour’) that protect the steel shell from abrasion; it
is also possible to use rubber as armour rather than
manganese steel.
View Inside Ball Mill (armour plates are the square shapes)

14. D. Ring Gear – a gear ring installed on the outer periphery of the drum.
E. Electric Motor – a motor used to rotate the drum. The motor drive
train leads to a gearbox than a ring gear. The motor is usually fitted with
a variable speed drive (VSD) to control the rpm of the ball mill.

F. Gearbox – used for speed reduction from the motor to the ball mill.
G. Balls – usually manufactured from manganese alloy steel, but the
material depends upon for what material the mill will grind (chrome
steel alloy and rubber also available). The size of the balls depends upon
the size of the drum, typical ball sizes are two to three inches in
diameter (four-inch balls are also possible).
H. Bearings – smaller ball mills use anti-friction cylindrical roller
bearings. Larger ball mills use trunnion bearings.

15. Notes:
If hard pebbles are used instead of steel balls, the mill is
referred to as a ‘pebble mill’.
If rods are used instead of steel balls, the mill is referred to
as a ‘rod mill’.
As a general rule of thumb, the larger the diameter of the
ball mill drum, the more efficient the grinding process will
be. This rule of thumb stops though once the diameter of
the drum reaches approximately 4m.
The cylinder may be of metal, porcelain or of rubber, to
reduce abrasion. The balls may be of metal, porcelain or
stones (pebble mill).

16. Working
The material to be grind is fed at angle of 60 degree into the
crushing zone and the product is discharged at 30 degree.
As the shell rotates the balls are lifted up on the rising side of
the shell and they cascade down from near the top of the shell.
The solid particles in between balls are ground and reduced in
size by impact.

If the rate of feed increased, coarser product will be obtained
and if speed of rotation is increased the fineness for a given
capacity is increases.
During grinding, the balls themselves wear and are
continuously replaced by new ones so that mill contains balls
of various ages.
Ball mill produces 1 to 50 ton/hr of powder and energy
requirement of the ball mill is about 16 kwh/ton.

17. A.At low speeds, the mass of balls will slide or roll over each other and negligible
size reduction will occur.
B.At high speeds, the balls will be thrown out to the wall by centrifugal force and
no grinding will occur.
C.At about two-thirds of the speed at which centrifuging just occurs, movement
takes place as shown, that is, the balls are carried almost to the top of the mill
and then fall in a cascade (tumble) across the diameter of the mill.

18. Applications & Uses
The ball mill is used for grinding materials such as
coal, pigments, and feldspar for pottery.
Grinding can be carried out either wet or dry but the
former is performed at low speed.
Blending of explosives is an example of an application
for rubber balls.
For systems with multiple components, ball milling
has been shown to be effective in increasing solid-
state chemical reactivity.
Ball milling has been shown effective for production
of amorphous materials.

19. Pharmaceutical uses of Ball Mill:
The small and average capacity Ball mills are used for
the final grinding of drugs or for grinding suspensions.
The maximum capacity Ball mills are used for milling
ores prior to manufacture of pharmaceutical
chemicals.
For production of ophthalmic and parenteral
products.
For milling dyes, pigments and
insecticides at low speed rotation.

20. Advantages
1)It can produce very fine powder (particle size less
than or equal to 10 microns).
2)It is suitable for milling toxic materials since it can be
used in a completely enclosed form.
3)Has a wide application.
4)It may be used for batch or continuous operation.
5)It is used in milling highly abrasive materials.
6)Ball mill is used for both wet and dry grinding
processes.
7)In the ball mill, installation, operation and
maintenance costs are low.

21. Disadvantages
1)Contamination of product may occur as a result of
wear and tear which occurs principally from the balls
and partially from the casing.
2)High machine noise level especially if the hollow
cylinder is made of metal, but much less if rubber is
used.
3)Relatively long milling time.
4)It is difficult to clean the machine after use.
5)Not easy to get thinner end product.
6)Soft, fibrous material cannot be milled by ball mill.