The document describes a report on ball mills submitted to professors at Cairo University. It discusses the basic principles of ball mills, their components, design equations, manufacturers, and cost estimates. Ball mills are widely used in grinding materials in industries like chemical and are available in both dry and wet types. They can be batch or continuous and are efficient tools for reducing materials to fine powder.

1. CAIRO UNIVERSITY
FACULTY OF ENGINEERING
CHEMICAL ENGINEERING DEPARTMENT
Principle of Mechanical Unit Operation
Report on: Ball Mill
Submitted to: Dr/ Ibrahim Ismail
Dr/ Ahmed Sherif
Prepared by: Group number 3

2. Table of content
1. Introduction................................................................................................................1
2. Basic principle............................................................................................................2
3. Description.................................................................................................................3
4. Equations of design....................................................................................................4
5. Manufacture of the equipment...................................................................................5
6. Cost of equipment......................................................................................................5

3. List of figure
Fig.1 Manhole of batch ball mill ...................................................................................1
Fig.2 Description of continues ball mill ........................................................................1
Fig.3 The speed of ball V.S. the time ............................................................................2
Fig.4 General description for ball mill ..........................................................................3
Fig.5 Wet ball mill description ......................................................................................4
Fig.6 Cost Ball mills, Ball charge are $31S/ton ............................................................6
Fig.7 Cost Ball mills dry grinding .................................................................................6
Fig.8 Cost Ball mills wet grinding ................................................................................7

4. Acknowledgment
Thanks to Dr. Magdy Abadeer for his co-operation with us in visiting some factories
to see the ball mill live and the name of the references that could help us in that
report.
Thanks to Dr. Ayman Zaky for his co-operation with us to get the cost of the ball mill
and get the cost of it for 2008.

5. Abstract
The Ball mill is one of the most important equipment in the world of chemical
engineering. It is used in grinding materials like ores, chemicals, etc.
The types of ball mills: batch ball mill and continuous ball mill with different grinding
media and different design depend on the nature of the input material and the nature
of the output which I need.
We discuss the types of ball mill, the basic principles of the ball mill, how it works,
the details of design including equations for optimum dimensions in all cases, some
manufacturers for the ball mill, and estimation of the cost the ball mill.

6. 1. Introduction
Ball mill is an efficient tool for grinding many materials into fine powder. The ball
mill is used to grind many kinds of row materials.
There are two ways of grinding: the dry process and the wet process. It can be divided
into tubular type and flowing type according to different forms of discharging
material.
Fig.1 Manhole of batch ball mill
• Batch ball mill :
The balls as will as the feed are charged through an opening in the lateral wall
and discharge is through an opening just opposite to the charging manhole.
In case of wet grinding the discharge opening is fitted with a valve to regulate
the flow of slurry.
Fig.2 Description of continues ball mill 1

7. • Continues ball mill :
To grind the material continuously that, to feed from one end and to collect the
discharge in a cyclone from other end with the help of a fan. The classifier
may be of mechanical type or for a very precise & fine separation variable
speed motor driven classifier is also available.
2. Basic principle
Ball mill is 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.
There is a specific operating speed for most efficient grinding. At a certain point,
controlled by the mill speed, the load nearest the wall of the cylinder breaks free and
it is so quickly followed by other sections in the top curves as to form a cascading,
sliding stream containing several layers of balls separated by material of varying
thickness. The top layers in the stream travel at a faster speed than the lower layers
thus causing a grinding action between them. There is also some action caused by the
gyration of individual balls or pebbles and secondary movements having the nature of
rubbing or rolling contacts occur inside the main contact line.
Fig.3 The speed of ball V.S. the time 2

8. 3. Description
Ball mill is a hollow axis made of steel parts with a replaceable lining. Major rotation
gear, machined by rolling wheel of casting, is lined with wearing plate with fine wear-
resisting property. This machine runs stably and reliably.
• General design for {wet and dry} ball mill
Fig.4 General description for ball mill
1 Bearing
2 Mill Shell
3 Driver
• Types of driver is { Central driver and Gear rim / pinion}
4 Inlet
• Types of inlet is { Inlet type, Inlet chute, and inlet screw }
5 Outlet
• Types of Outlet
• Over flow mills with/without screen cage
• Discharge diaphragm- outlet casing
• Central discharge
6 Gear Rim Lubrication
7 Water Injection
8 Motors
9 Lining
• Type of lining { steel, rubber, and ceramic lining }

9. • The description of wet ball mill
Fig.5 Wet ball mill description
4. Equations of the design
By knowing the capacity quot;Cquot; {ton} of the feed; we can get approximately the length
quot;Lquot; {mm} and diameter quot;Dquot; {mm} of the batch ball mill, form
**D = 124.2*(C) + 485.7
**L= 85.71*(C) + 1854
Volume of mill = ^2
The bulk volume of balls charge ratio to the volume of mill is known as {Filling
ratio} and its range is {30-45%}
^2
______________________________________________________________
** Note: There is not directly sizing equation, so I get the specifications quot;dimensionsquot;
of batch mill and I but the data in excel to get the equations of quot;Lquot; and quot;Dquot;. 4

10. 4.1 Size of Balls:
Where dimensions are in meters and K is a constant depending on the grind ability of
the solid. Its value ranges from 0.9 to 1.4.
4.2 The speed of the shell:
The maximum speed avoiding centrifugal force
, Where
4.3 Mass of balls
The bulk volume of the balls is {30-45%} of the volume of the shell of the ball mill
and the feed is filling the empty space between the balls where the static porosity is
about 40% ,and the balls charge is vary from 30-45%
5. Manufactures of the equipment:
1. Christian Pfeiffer.
2. British Rema.
3. Shanghai Zenith Company.
4. Shanghai Shibang Machinery Company.
5. Henan Chuangxin Building-Materials Equipment Company.
. Jiangsu Pengfei Group Nangtong Heavy Machinery Company.
6. Cost of the equipment:
This charts show the cost in US Dollar of ball mill, by knowing the capacity in
(Ton/hours) of the charge, but this price for 1990.
The Price including of installation, classifier, motors, drives, and an average
allowance for foundations and erection. But they do not include freight, auxiliary
equipment, or equipment for handling the material.
5

11. Fig.6 Cost Ball mills, Ball charge are $31S/ton
Fig.7 Cost Ball mills dry grinding
6

12. Fig.8 Cost Ball mills for wet grinding
• To get the price of the ball mill for 2007:
7

13. Summary
The Ball Mill is designed to grind materials by turning the cylindrical shell with
grinding medium (e.g. steel balls) put in the shell, and has a simple structure and ease
of handling. Furthermore, The Ball Mill of a large capacity has been available to a
very extensive range of applications in both dry and wet

14. References
1. Max S. Peters and Klaus D. Timmerhaus, Plant Design and Economics for
Chemical Engineers, McGraw-Hill, Third Edition, 1991.
2. Don W. Green and Robert H. Perry, Perry's Chemical Engineers' Handbook, Eighth
Edition, 1999.
3. www.metsominerals.com
4. http://zenithcrusher.com/
5. http://www.christianpfeiffer.de/
6. http://www.britishrema.co.uk/
7. http://cnpf.en.alibaba.com/
8. http://www.shibang-china.com/
9.http://www.pauloabbe.com/productLines/millingEquipment/principlesofgrinding.ht
ml
10. http://cnchuangxin.en.alibaba.com/
11. http://www.preciousfabcast.com/ballmill.html
12. http://www.yaqiuji.net/ecp/eqmj.htm
13. http://www.86371.cn/Ball%20mill.htm