FIELD OF INVENTION
The present invention relates to a construction of shell liner materials for ball tube
mill to sustain high wear resistance against hard ball impact during operation and a
method of manufacture the liners in the ball mill
BACKGROUND OF THE INVENTION
In practice, the Ball tube mills are engaged for pulverization of coal to the specific
classification for easy and complete burning of the coal, the raw coal is fed in to the
shell having hard, thick material lining (having lifting surface contour) and
containing large quantity of hard balls. The Shell is rotated slowly with the help of
electric motor and step down gearboxes. The coal is pulverized due to impact of
loose hard balls on the coal and also due to attrition. The raw coal and balls rotate
on the Shell liners resulting in high wear of the Shell liners.

The shell liners are normally made of manganese steel or High Chrome cast iron
having wear life of 8000 to 25000 hrs. of operation. This invention emphasize on
implementation of a shell liner materials for long & service free usage (40,000 to
50,000 operating hrs.).
Also, due to drastic reduction in rotating mass the power requirement is reduced by
25%; resulting in lower size power drive system.
The Coal pulverized (typical shown in Fig.l) are used for pulverizing the coal by
feeding pre-crushed raw coal into long rotating the tube having large quantity of
small balls (normal quantity of balls is 60 to 80 tons having diameters as 30, 40 and
50mm). Due to the impact of balls on coal and due to attrition of coal and balls on
the shell liners the coal get pulverized. The pulverized coal is carried up by hot air to
classifier zone. The classifier is fitted in the pulverized coal air path for segregating
the coarser coal particles from fine coal particles. The coarser coal particles are sent
back for further grinding while the fine coal particles are further transported to its
end use i e. burning is suspended condition.

The existing shell (shown in Fig. 2) is fabricated Tube made of thick steel plate
having large diameter. The inside surface of the shell is covered by large number of
thick castings for protecting the shell body and also for lifting the balls for
pulverization of coal. The liners are fitted on the shell by bolting.
The shell of the ball mill is made up of steel material and the Shell liners are castings
of either Manganese steel or High Chrome cast iron. The large quantities of balls,
which are rotating inside the shell, are made up of forged steel or High Chrome steel
castings. Due to abrasive nature of coal the liners and balls are worn out over a
period. The normal life of shell liners is in range of 8000 to 25000 working hours of
the pulverization. Once the balls or Shell liners are worn out they are replaced with
the new ones.
RELATED PATENTS
EP0794008 Bl Nov. 2001 Ball Mill - Alstom France
US4580734 July 1984 Rotary Pulveriser Ball Mills
US4678530 Nov. 1985 Method of making liner sections for rotary pulveriser

US5752665 July 1996 Grinding Mill Liners Adopter
US6036127 Oct. 1997 Mill lining elements.
CLOSEST PRIOR ART
The existing Shell liners are castings of Manganese steel or High Chrome cast iron
bolted on the shell plate.
PROBLEM ASSOCIATED WITH PRIOR ART
The shell Liners gets worn out due to rubbing of abrasive coal and balls on the
surface resulting in fast wear and frequent replacement of the components.
DISADVANTAGE
There are 400 shell liners per Ball Tube mill, each weighing 90kgs. Hence the cost of
replacement after worn out is very high. This increases cost of operation of the
Power Plants."

The replacement of the shell liners needs shut down of the mill and is time
consuming process.
THEORETICAL STUDY
As per the theory of erosive wear, if the angle of incidence of the stream is less,
then it is preferred to have Ceramic material which has very high hardness. The
superior wear properties of ceramic tile over High Chrome casting (more than two
times) was confirmed by extensive laboratory tests.
The Computational Fluid Dynamic (CFD) analysis is carried out to find out the lifting
activity of the liner and angle of impingement. The result shows that the angle of
impingement is low, suggesting that ceramic would perform better in this situation.
(Due to higher hardness and smooth surface). This will result in less wear and
longer life.

LBORATORY TEST
Extensive laboratory tests were carried out to study the wear of ceramic tiles and its
comparison with other liner material like manganese steel, High Chrome casting etc.
Also the breakage of liners due to impact of balls was studied and the composition
ascertained to ensure no breakage takes place.
OBJECTS OF THE INVENTION
It therefore, an object of the present invention to a propose a Shell liner material
and a process of installation thereof which eliminates the disadvantages of the
existing shell liner.
Another object of the present invention is to propose a Shell liner material and a
process of installation thereof which increases the liner wear life.

A further object of the present invention is to propose a Shell liner material and a
process of installation thereof which saves power for rotation of ball due to less
weight of new liner material.
A further object of the present invention is to propose a Shell liner material and a
process of installation thereof which saves break-down hours.
An yet further objection of the present invention is to propose a Shell liner material
and a process of installation thereof which saves the cost of procuction.
SUMMAARY OF THE INVENTION
A improved Shell liner materials having high wear resistance and a method of
installation of liner material inside a ball mill comprises a cylindrical shape and a
oblique wave shape ceramic tile liner and each ceramic tile is sandwich with a
supporting plate and each ceramic liner plate is provided two holes, first one for
fastening with a bolt and second is fixed up by welding tag.

A method for installation of Shell liner material comprises the steps of placing the
ceramic tile inside the periphery of the ball drum and placing a bolt through a first
cylindrical hole of the liner plate and supporting plate and through a shell plate via a
pipe in between supping plate and shell plate and fixing a nut with the bolt from
outside the shell plate and welding a tag with the supporting plate in the second
hole and covering both the holes with ceramic tiles.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Fig.l Drawing shows the typical Ball tube Mill with drive system.
Fig.2 A Drawing shows the shell with support.
Fig.2 B Drawing show shell liners assembly.
Fig.3 a Drawing show the existing cylindrical shell liner.
Fig.3 b Drawing show the existing oblique wave shell liner.
Fig.4 a Drawing shows the ceramic tiled cylindrical liner.

Fig.4 b Drawing shows the ceramic tiled oblique wave liner.
Fig.5 Drawing shows the Ceramic tile and Liner fixing arrangement.
DETAILES DESCRIPTION OF THE INVENTION
As shown in Fig.l: The ball tube mill consist of cylindrical shaped drum (6) Shell
supported on two trunnions on both sides (9) with a electric motor and gear drive
system. The Shell (6) is covered from inside by shell liners (7) to protect the shell
plate (6) and to lift the balls (5). The coal is fed from a coal feeder (1) which passes
through a mixing box (2) to reach a convey or screw assembly (3) which pass coal
to the ball mill through screw ribbon (4). The balls (5) fall on raw coal during
rotation resulting in breaking of the save. The coal and balls rotate on the Shell liner
(2) inside the shell (6). Over a period the coal is ground and is taken out to furnace
by hot air and course particles are returned back from a classifier (8) to the ball mill
for further crushing.
As fig-2A shows a isometric outer view of ball mill having a trunnion (9) and a shell
(6) and our inspection door (10).

Fig-2B shows an isometric inside sectional view to show an assembly of the existing
high chrome cast plate cylindrical liners (11) and oblique wave liner (12) covering
inside the shell in the prior art.
Fig-3A & B shows cylindrical shell liner and oblique wave shell linear over the shell in
the prior art.
METHOD OF INSTALLATION THE CEREMIC LINNING
As shown in fig. 4a and b - The ceramic tiles comprises (s) cylindrical shape ceremic
tile and (b) oblique wave ceremic tile which are installed on the inside periphery of
the cylindrical drum (6).
The cylindrical shape tile comprises a conical shape hole (13) and a support liner
plate (14) and a holding bolt (15) and a support pipe (16). The oblique shape linear
comprises two peaks and centrally valley shape tiles having two holes for fastening
with bolt and weld tag.

As shown in Fig.5 each shape of ceramic liners are fastened by means of a holding
bolt (17) and a holding nut (12). The holding bolt (17) is inserted through a conical
hole (18) of the ceramic tile and adjacent linear support plate (19) and passed
through a shell plate (20) via a pipe (21) disposed in between support plate (19)
and shell plate (20). A nut is (23) fixed up with the bolt (17) from outside the shell
plate ( 20) through a washer (22). The top of the bolt is covered with a ceramic tile
(24).
A second hole (25) is tag welded from the outside of the liner with the liner support
plate (19) and deposited weld material (27) on the support plate (19). After welding
the hole is covered with a ceramic cover (28).

WE CLAIM
1. A improved Shell liner materials having high wear resistance and a method of
installation of liner material inside a ball mill comprises:
- a cylindrical shape and a oblique wave shape ceramic tile liner;
- each ceramic tile is sandwich with a supporting plate;
- each ceramic liner plate is provided two holes, first one for fastening
with a bolt and second one is fixed up by welding tag.
2. A method for installation of Shell liner material as claimed in claim 1
comprises the steps of:
- placing the ceramic tile inside the periphery of the ball drum;
- placing a bolt through a first cylindrical hole of the liner plate and
supporting plate and through a shell plate via a pipe disposed in
between supping plate and shell plate;
- fixing a nut with the bolt from outside the shell plate with a washer;

- welding a tag with the supporting plate in the second hole.
- covering both the holes with ceramic tiles.
3. The improved shell liner material and a method of installation of the liner
materials as substantially described herein along with the accompanying
drawings.

ABSTRACT

A improved Shell liner materials having high wear resistance and a method of
installation of liner material inside a ball mill comprises a cylindrical shape and a
oblique wave shape ceramic tile liner and each ceramic tile is sandwich with a
supporting plate and each ceramic liner plate provide two holes, first one for
fastening with a bolt and second is fixed up by welding tag.