4. TABLE OF CONTENT:
INTRODUCTION
DEFINITION
BASIC PRINCIPLE
CONSTRUCTION
WORKING
ADVANTAGES AND DISADVANTAGES
APPLICATIONS
EQUATIONS
5. BALL MILL
INTRODUCTION:
• It is efficient tool for grinding many
materials into fine powder.
• There are two types of grinding, the
dry process and wet process.
6. DEFINITON:
• A ball mill is a type of grinder used to grind
and blend materials for use in mineral
dressing processes, paints, pyrotechnics,
ceramics and selective laser sintering etc.
7. 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.
8. CONSTRUCTION:
Wet or dry ball mill grinding machine
consists of following parts:
1. Feeding part
2. Discharging part
3. Turning and driving part( gear, motor etc)
4. Rotating balls
9. CONSTRUCTION (CONT):
Consist of a hollow cylindrical shell rotating about its
axis.
The axis of the shell may be horizontal or at some
angle.
It is partially filled with balls.
These balls are grinding materials, made up of
chrome steel, stainless steel or rubber.
The inner surface of the hollow cylinder is lined with
a resistant material such as manganese steel or
rubber.
10. CONSTRUCTION (CONTD)
The length of mill is approximately equal to
its diameter.
Ball occupy about 30-50% of the volume.
The dia of ball is 12mm to 125mm.
The dia of shell is 3m and its length is about
4.25m.
The shell is rotated through a drive gear
with speed 60-100 rpm.
11. 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.
12. 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.
13.
14. ADVANTAGES OF BALL MILL
The cost of installation is low.
The cost of production is low.
It is suitable for materials of all degree of
hardness.
The grinding medium is cheap.
Suitable for both batch and continuous
operations.
15. DISADVANTAGES:
Rotational ball loading difficulty
Mill efficiency is low
The mill feed size range is wide
Not easy to get thinner end product
