CAIRO UNIVERSITY

FACULTY OF ENGINEERING

CHEMICAL ENGINEERING

Principle of Mechanical

Report on: Ball Mill

Submitted to: Dr/ Ibrahim

Dr/ Ahmed Sherif

Prepared by: Group number

NIVERSITY

NGINEERING

NGINEERING DEPARTMENT

Principle of Mechanical Unit Operation

Ball Mill

Submitted to: Dr/ Ibrahim Ismail

Dr/ Ahmed Sherif

Group number 3

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

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

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.

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.

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

• 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

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 }

• The description of wet ball mill

Fig.5 Wet ball mill description

4. Equations of the design

By knowing the capacity "C" {ton} of the feed; we can get approximately the length

"L" {mm} and diameter "D" {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%}

� � ���� ������ �� ����� ������ �� ����

� ��� !�"# !$ %&# �'( � � � ��)4� � ��^2 � �

______________________________________________________________

** Note: There is not directly sizing equation, so I get the specifications "dimensions"

of batch mill and I but the data in excel to get the equations of "L" and "D". 4

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

-critical � �30 � $/�7�89 :, Where $ � 0.65 9 0.75

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%

� "'(( !$ %&# �'( � ����� !�"# !$%&# �'( � ���� ?#@(A%B !$ �'(� � ��� ?#@(A%B !$ �'( � ��1 9 D � �?#@(A%B !$ �'�

� E balls � �� ) � � � ��+ � �1 9 D � �Hball�4

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.

6. 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

Fig.6 Cost Ball mills, Ball charge are $31S/ton

Fig.7 Cost Ball mills dry grinding

6

Fig.8 Cost Ball mills for wet grinding

• To get the price of the ball mill for 2007:

I!(% !$ �' "A A@ 2007 � ��I!(% A@ 1990 � �I!(% A@?#L A@ 2007��I!(% A@?#L A@ 1990

I!(% A@?#L $!: 2007 � 533.1

I!(% A@?#L $!: 1990 � 357.6

7

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

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