• Author / Uploaded
• ISLAM I. Fekry

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Ball Mill Group No. 3

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Contents

Introduction Types and Process Principle of work Description of Ball mill Design and Cost

Introduction


It is a device used for size reduction, It can reduce sizes up to a tenth of a micron.
Cylindrical in shape.
Rotates on a horizontal axis.
Partially filled with the material to be ground and the grinding medium.

Ball Mill Group No.3

Types and Process

Types and process

There are two Processes

There are two Types

1. Wet Process 2. Dry Process

1. Continuous 2. Batch

Ball Mill Group No.3

Principle of ball mill


The rpm of mill
The difference in speed between balls

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Description

A

Inlet

Drive

B C Outlet

D Mill Internals

Ball Mill Group No.3

A. Inlet


INLET TUBE mostly for wet mills
INLET CHUTE with fresh air flap for mill ventilation
INLET SCREW for problematic feed materials Ball Mill Group No.3

Types of inlet

1- TUBE

2- CHUTE

B.3- SCREW

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B. Drivers

1- CENTRAL

2- GEAR RIM/PINION

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Types of drives


CENTRAL DRIVE
GEAR RIM / PINION with one pinion or double pinion

Ball Mill Group No.3

C. Outlet


OVERFLOW MILLS WITH/WITHOUT SCREEN CAGE for wet mills


DISCHARGE DIAPHRAGM for wet and dry mill


CENTRAL DISCHARGE for dry mills

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Types of Outlet

1- OVERFLOW

2- DISCHARGE DIAP.

3- CENTRAL

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D. Mill Internals


STEEL LINING for wet and dry mills
RUBBER LINING for wet mills
CERAMIC LINING for iron-free grinding Ball Mill Group No.3

Types of Mill Internals

STEEL

RUBBER

CERAMIC

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Fastening systems

Bolted version

Semi-bolted version

Boltless version

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ERECTION of COMPACT LINING

Design IMPORTANT DATA TO DESIGN A Ball MILL Feed material:

Environment:

Temperature [°C]: Grain size [80% < x µm]: Work Index acc. Bond [kWh/t]: Feed quantity [kg/h]:

Altitude [m a.s.l.] Ambient temperature [°C]

Process: Dry / wet grinding Open / closed circuit Grinding media

Product: max. temperature [°C]: Grain size [80% < x µm]:

Ball Mill Group No.3

Calculation
Feed capacity → Mill dimensions
Filling ratio (30-45%), Mill dimensions → Bulk volume of the balls
ball size : D2 = k * Dp (where k ranges from 0.9 to 1.4)
Speed of the shell Ncritical = (30*f)/√(R-r), where f =0.65-0.75
Mass of balls = Bulk volume * Bulk density

Ball Mill Group No.3

Cost

Cost Ball mills, Ball charge are $315 S/ton Ball Mill Group No.3

Cost Ball mills dry grinding

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Cost Ball mills for wet grinding

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To get the price of the ball mill for 2007
Cost 2007 =(Cost 1990)*(Cost index 2007)/(cost index 1990) Cost index 2007=533.1 Cost index 1990=357.6

Ball Mill Group No.3

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