Report on Cement manufacturing process

A
Report on
Internship Taken
At
DCM Shriram Limited
Kota (Raj.)
Submitted in partial fulfillment of the requirement for the degree of
Bachelor of Technology, Mechanical Engineering
Duration- June 5, 2015- July 20,2015
Academic session – 2015-16
Submitted to
Mr. Sanjeev Mittal
(GM-Cement, DCM)
&
HOD
Dept. of mechanical Engineering.
Career Point University, Kota
Submitted by:
Rohan Sharma
B.Tech Mechanical
(4th year)
Career Point University. Kota

Industrial Internship Training Report 2015-16 | 1
Index
S.No Title Page no.
1 Acknowledgement 2
2 Introduction 3
3 About DCM Shriram cement works 4
4 Cement 5
5 Crushing plant 7
6 Raw mill 12
7 Kiln section 18
8 Electrostatic precipitator 22
9 Clinker cooler and coalsection 24
10 Cement mill 26
11 Packaging plant 28
12 Quality control 29
13 Conclusion 30

Acknowledgement
I am very grateful to Mr. Nigam Prakash (jt. VP HR), Mr. Sanjeev Mittal (GM-
Cement) and Department of Mechanical Engineering, Career Point University, Kota
for giving me this opportunity to undergo practical training in this esteemed
organization. They took personal interest in my training and provided me all the
necessary guidance, and required help.
My thanks to all staff members who supervised my work from time to time and
helped me in understanding the entire cement manufacturing process and all other
machinery. They were the key in teaching the complexities of whole system.
My special thanks to Mr.Ashish Mittal, Mr.S.C Sharma and Mr.Vidhyasagar for
supporting me throughout the training in terms of guidance, motivation and all other
essential spheres.

Introduction
The origin of the DCM dates back to 1889, when Delhi Cloth & General Mills was
established. Founded by Lala Sri Ram, DCM started its journey with the
incorporation of a public limited Company on March 26, 1889 in the name and style
of Delhi Cloth & General Mills Co. Limited under the provisions of Act VI of 1882.
Over the years, the DCM Group became one of India's largest conglomerates.
Consisting of a large number of Companies/Divisions, reputed for their product
quality, dynamism and business integrity along with their quick response to changes
in the environment. It expanded and diversified its activities into a number of
manufacturing activities such as Textiles, Sugar, Chemicals, Rayon, Tyre Cord,
Fertilizers, Information Technology and Engineering Products etc. The name of the
Company was changed on October 6, 1983 to DCM Limited.
One of the main reasons for the Group's success is its focus on technology and
quality. With the backing of its people, its technology and its alliances, the DCM
Group is able to tackle any challenges that come its way.
World over, the 80's was the decade of diversification. However, the 90's were a time
for consolidation and focusing on core business areas. The DCM Group, too, decided
to move out of those business ventures, which did not fit, into its overall strategic
vision. Its thrust is now on value-added products, on high technology sunrise
industries.
The business of the Company was reorganized with effect from 1.4.1990 under a
Scheme of Arrangement under section 391 / 394 of the Companies Act, 1956
approved by the shareholders, creditors and the financial institutions and sanctioned
by the Honorable High Court of Delhi at New Delhi in 1990. Under the said
reorganization, all units of the Company existing at that time stood vested and / or
continued to vest in terms of the said Scheme into four separate companies namely,
 DCM Limited
 DCM Shriram Industries Limited
 DCM Shriram Consolidated Limited
 Shriram Industrial Enterprises Limited

About DCM Shriram cement works
Shriram Cement is a unit of DCM Shriram Ltd.
SCW is a wet process cement plant based on calcium hydroxide sludge of sister
calcium carbide plant, located in the same complex. SCW was commissioned in 1987
with the technical know-how from M/s. Lafarge Coppee Lavelin, France. Products of
the plant are OPC-53 grade, Shriram Nirman (PPC) and Shriram Silver (PPC).
Besides these products, trading of POP is also carried out. The plant is certified for
ISO 9001, 14001 and OHSAS 18001 for its effective Quality, Environment, and
Occupational Health and Safety Management Systems. It has also been awarded five
star certificates by British Safety Council for its effective safety systems.
Installed capacity of SCW is 4.0-lakh tons cement per annum.
Shriram cement is known for high quality for last several years. Following are the
major special properties:
 Cement manufactured by SCW is marketed under the "Shriram" brand.
 Shriram cement has created for itself strong brand equity, enjoying a premium
over competitor brands, and is recognized as a market leader in its areas of
distribution.
 Shriram Cement is available in three different varieties, Shriram 53, Shriram
Nirman and Shriram Silver. Shriram Silver is specialty cement, which is used
for mosaic floor and grit wash.
 Shriram market Plaster of Paris under the brand name Shriram Nirman POP,
which is a cosmetic product, used for finishing of walls and making cornices
and molding and different designs of fall ceiling.
Cement

Cement is a binder, a substance that sets and hardens and can bind other materials
together. Cement is essentially a binding material used for making concrete, which in
turn the basic material for building dams, bridges and other construction works.
Cement has an exceptional strength under compressive loads and also it can take any
shape.
Types of cement
 Ordinary Portland cement (OPC)
 Portland pozzolona cement (PPC)
 Sulphate resisting cement
 Rapid hardening cement
 Oil well cement
 Masonry cement
 Portland blast furnace slag cement
 Super Sulphate cement
 High alumina cement
 White grade cement
 Quick setting cement
 Hydrophobic cement
 Silver grade cement
In DCM Shriram cement works three types of Cement is manufactured:
 Ordinary Portland cement
 Portland pozzolona cement
 Silver grade cement
There are three processes of manufacturing cement which are known as the wet, dry,
and semidry processes and are so termed when the raw materials are ground wet and
fed to the kiln as a slurry, ground dry and fed as a dry powder, or ground dry and then
moistened to form manufacturing of cement.
In DCM Shriram cement works cement is manufactured via wet process.
The manufacture of cement is a very carefully regulated process comprising the
following stages:
1. Quarrying - a mixture of limestone and clay.
2. Grinding - the limestone and clay with water to form slurry.
3. Burning - the slurry to a very high temperature in a kiln, to produce clinker.
4. Grinding - the clinker with about 5% gypsum to make cement.
 Raw Materials Extraction
The limestone and clay occur together in quarries. It is necessary to drill and blast
these materials before they are loaded in trucks. The quarry trucks deliver the raw
materials to the crusher where the rock is crushed to smaller than 12mm. The raw
materials are then stored ready for use.

 Raw Materials Preparation
About 80% moisture contained slurry comes from carbide plant and acetylene plant,
which is the by-product of those plants. Adjusting the relative amount of limestone
and clay being used very carefully controls the chemical composition of the slurry.
The slurry is stored in large basins ready for use known as decanter and DP tanks and
then further fined by raw mill.
 Clinker Burning
The slurry is fed into the upper end of a rotary kiln, while at the lower end of the kiln;
a very intense flame is maintained by blowing in finely ground coal. The slurry
slowly moves down the kiln and is dried and heated until it reaches a temperature of
almost 1500 degrees Celsius producing "clinker". This temperature completely
changes the limestone and clay to produce new minerals, which have the property of
reacting with water to form a cementitious binder. The hot clinker is used to preheat
the air for burning the coal, and the cooled clinker is stored ready for use.
 Cement Milling
The clinker is finely ground with about 5% gypsum in another mill, producing
cement. (The gypsum regulates the early setting characteristic of cement). The
finished cement is stored in silos then carted to our wharf or packing plant facilities.
Figure 1: Process layout of cement manufacturing
Crushing Plant

The crushing plant receives limestone from mines and in two stages operation crushes
it into size of 12mm. there are two crushers, primary crusher of L&T (double toggle
jaw crusher) and secondary crusher of Economer (Hammer crusher). Crushers have
capacity of 100 ton per hour and are driven by 132 KW motors. The crushed
limestone is stored in yard of 2 miles.
 Equipments and their Flow Diagram:
Figure 2: Process layout of crushing plant
 Unloading hopper:
Stacker system
C-4 Conveyer
Vibrating screen
C-3 Conveyer
Hammer Mill
vibro feeder
Intermideate hopper
C-2 Conveyer
C-1 Conveyer
Jaw Crusher
Apron feeder
Unloading Hopper

The limestone from Bundi and Ramganjmandi comes into plant in loaded trucks and
is unloaded here in the chambers having rectangular sections .The capacity of
Unloading Hopper is 60 Metric ton.
 Apron feeder:
Apron feeders were designed for uniform and regulated feed of loose and lump
materials from feed bin to crushing aggregates and transporters of different types. The
transporting cloth of apron feeders is a closed circuit, consisting of plates, which are
connected hingedly. The productivity of feeders is regulated at the expense of cloth
speed changing and size of bin outlet. The transporting cloth is activated with drive
sprocket; direction and chain supporting are implemented with the shaped rolls. To
regulate the cloth tension the screw mechanism of back sprocket movement is used.
The capacity of Apron feeder is 150 tons per hour.
Figure 3: Apron feeder
 Jaw Crusher:

Jaw crusher is also named jaw breakers, rock crusher, or rock breaker. Jaw crusher is
mainly used to primarily and secondarily crush many kinds of mining rocks, and the
highest anti-pressure strength of crushed material is 320Mpa.
 Features of Jaw Crusher:
 Simple structure, reliable working condition, easy maintenance, low operating
costs;
 High crushing ratio, even final particle size products;
 Deep broken cavity, no dead zone, increased capacity;
 Safe and reliable lubrication system, convenient replacement parts;
 Stand-alone energy-saving 15% ~ 30%;
 The discharging size of jaw crusher can be adjusted to meet the users' different
requirements.
 Structure of Jaw Crusher:
 The structure of jaw crusher: main frame, eccentric shaft, a large belt pulley,
fly wheel, swing jaw, side guard plate, toggle plate, Rear bracket, adjust gap
screw, reset spring, and fixed jaw and swing jaw board etc., and the toggle
plate also plays a role of protection. The length of toggle is 898 mm (movable
jaw) and 790 mm (fixed jaw).
Figure 4:Jaw crusher
 Working Principle of Jaw Crusher:

 The motor drives the movable jaw plate to do periodic motion towards the
fixed jaw plate by the eccentric shaft.
 The angle between toggle plate and movable jaw plate increases when
movable jaw plate moves. So the movable jaw plate moves towards the fixed
jaw plate.
 The material between the movable jaw plate and fixed jaw plate will be
crushed in this process. The angle between toggle plate and movable jaw plate
decreases when
Movable jaw plate moves down, the movable jaw plate move leaves fixed jaw plate
by pulling rod and spring, the final crushed material will be discharged from the
outlet.
The capacity of Jaw Crusher is 130 tons per hour
 Hammer crusher:
Hammer crusher is a kind of machine widely used in crushing medium hardness
materials such as Limestone, slag, coke and coal in Cement, chemical industry,
electric power, metallurgy, etc. Hammer crusher broken materials mainly rely on
impact. The crushing process is roughly like this, materials into the hammer crusher,
and broken by the impact of high-speed rotary hammerhead. Then the broken
materials obtained kinetic energy from the hammerhead and rushed to frame and
screen with high speed.
Figure 5
The materials collisions with each other at the same time, after repeatedly broken, the
materials less than sieve article eduction from the gap. Individual larger materials

impact by the hammerhead again, grinding, extrusion and broken. At last, deduction
from the gap. Thus obtaining products with required size. It is made by manganese
steel.
 Working principle
The main working part of the Crusher is the rotor with hammer rings. The rotor is
consisted of hammer ring shaft and the ring hammer, etc. The rotor driven by motor
rotates at a high speed in the crushing chamber. The materials are conveyed into the
chamber from the top inlet, then impact by the high-speed rotating hammer ring, thus
crashed, squeezed ground among the materials and finally achieved the goal of
crushing. At the bottom of the rotor, there are grate plate equipped, the crushed
materials which smaller than the grate hole size can be discharged through the grate
plate, while the larger ones will be crushed by the hammer ring till the required size
and be discharged.
The capacity of Hammer mill is 130 tons per hour.
 Vibrating screenor DSM screen
The function of DSM (Dynamic screen manager) screen is to only pass the particles
with size of not more than 12mm. It consists of vibration damper of 6-12 mm. The
rejected particles are again feed into crusher and the remaining is sent to the yard via
belts. Before coming to screen the particles are moved below the magnetic separator
so that all particles with magnetic properties shall be kept aside from the process.
After the screen there is placed a dust collector.
 Raw material handling section
The stored limestone is reclaimed is from yard by the help of reclaimer. This
equipment is supplied by space age limited. Its capacity is 100 ton per hour. The
reclaimer shaves one side of the pile in such manner that further blending of
Limestone occurs. The reclaimed limestone is conveyed to the raw mill through belts.
Figure 6: Reclaimer & Stacker
Raw Mill

A Raw mill section used to grind raw materials into " rawmix" during the
manufacture of cement. Rawmix is then fed to a cement kiln, which transforms it into
Clinker, which is then ground to make cement in the cement mill. The raw milling
stage of the process effectively defines the chemistry (and therefore physical
properties) of the finished cement, and has a large effect upon the efficiency of the
whole manufacturing process.
Figure 7: Raw Mill

Figure 8: process layout of Raw Mill
slurryfrom
carbide plant
decanter
DP Tank 1 DP Tank 2
Drum Filters
Raw mill
DSM Screen
Slurry mixer tank
feeder
crushed
limestone from
crushingplant

 Decanterand DP Tank
Calcium hydroxide sludge available from acetylene plant is pumped into the decanter.
The decanter is a large tank with a diameter of 25 m .it is operated on recirculation till
sludge of 68% - 69% moisture is reached in the outlet. The decanter sludge is than
pumped into DP Tank (Daily precipitation tank). There are two such tanks having
capacity of 600 m3/hour. Here, sludge is continuously agitated to that sludge doesn’t
solidify. From decanter, sludge is also sent to lagoons where it is naturally decanted
over the years before cement plant inception. Mechanical shovel and dumpers do this.
The pumping capacity of DP Tank is 65m3/hour.it pumps the sludge to the feeder on
the top of the Raw mill building.
Figure 9: DP Tanks
Figure 10: Decanter

 Feeder
The feeder is a ferries wheel driven by a variable DC drive. There are three hoppers in
a raw mill building .one for the limestone received from the yard after proper
blending, second for high grade limestone used sometimes to improve the limestone
content to the burn ability or melting characteristics of raw mix the clinkerization
section.
 Raw mill
 Layout
A Raw/Ball mill is a horizontal cylinder partly filled with steel balls (or occasionally
other shapes) that rotates on its axis, imparting a tumbling and cascading action to the
balls. Material fed through the mill is crushed by impact and ground by attrition
between the balls. The grinding media are usually made of high-chromium steel. The
smaller grades are occasionally cylindrical ("pebs") rather than spherical. There exists
a speed of rotation (the "critical speed") at which the contents of the mill would
simply ride over the roof of the mill due to centrifugal action. The critical speed (rpm)
is given by: nC = 42.29/√ d, where d is the internal diameter in meters. Ball mills are
normally operated at around 75% of critical speed, so a mill with diameter 5 meters
will turn at around 14 rpm.
The mill is usually divided into at least two chambers,(Depends upon feed input size
presently mill installed with Roller Press are mostly single chambered), allowing the
use of different sizes of grinding media. Large balls are used at the inlet, to crush
clinker nodules or limestone (which can be over 25 mm in diameter). Ball diameter
here is in the range 60–80 mm. In a two-chamber mill, the media in the second
chamber are typically in the range 15–40 mm, although media down to 5 mm are
sometimes encountered. As a general rule, the size of media has to match the size of
material being ground: large media can't produce the ultra-fine particles required in
the finished cement, but small media can't break large clinker particles.
A current of air is passed through the mill. This helps keep the mill cool, and sweeps
out evaporated moisture, which would otherwise cause hydration and disrupt material
flow. The dusty exhaust air is cleaned, usually with bag filters.
Figure 11: Layout of Mill

 Specification
A Raw mill is driven by 750 KW motor that rotates the mill at 17 rpm. The length of
mill is 13 m and diameter is 2.25 m. Both the compartments of mill are filled with
grinding media apart from sludge and limestone.in first compartment high steel balls
are put which are responsible for coarse grinding.
First chamber is filled in accordance with following data:
Size of ball (in mm) % In tank
90 3
80 8
70 8
60 9
The second compartment contains balls of high chromium steel, which are
responsible for grinding limestone and iron. About 36 % of compartment is filled with
these balls.
Second chamber is filled in accordance with following data:
Size of balls (in mm) % In tank
50 20
40 10
30 6
A circular section called diphagram, which is having 12 small screens at different
periphery, separates both the compartments. Molasses is also added in raw mill .it is
required to increase the slow ability of the raw mix at low moisture.
 DSM Screen
The raw mill outlet slurry goes to war man pump, which pumps the slurry to DSM
Screen. Here the fine particles passé through the drum filters and goes to slurry mixer.
The coarse particle goes back to the mill to further grinding.
 Slurry mixer tank
The slurry mixer is 12.5 m diameter tanks having arms on which air nozzles are fixed.
Compressed air through these nozzles about 1.5 kg/cm3 agitates the slurry and

prevents it from becoming solid. From here the slurry is feed into kiln by slurry
pumps.
Figure 12: DSMScreen Figure 13: Slurry mixertank

Kiln Section
A Rotary kiln is a pyro processing device used to raise materials to a high temperature
(calcination) in a continuous process. The basic components of a rotary kiln are the
shell, the refractory lining, support Tyres and rollers, drive gear and internal heat
exchangers.
Figure 14: Kiln
 Kiln Shell
This is made from rolled mild steel plate, usually between 15 and 30 mm thick,
welded to form a cylinder, which may be up to 230 m in length and up to 6 m in
diameter. This will be usually situated on an east/west axis to prevent eddy currents.
Upper limits on diameter are set by the tendency of the shell to deform under its own
weight to an oval cross section, with consequent flexure during rotation. Length is not
necessarily limited, but it becomes difficult to cope with changes in length on heating
and cooling (typically around 0.1 to 0.5% of the length) if the kiln is very long.
 RefractoryLining
The purpose of the refractory lining is to insulate the steel shell from the high
temperatures inside the kiln, and to protect it from the corrosive properties of the
process material. It may consist of refractory bricks or cast refractory concrete, or
may be absent in zones of the kiln that are below around 250°C. The refractory
selected depends upon the temperature inside the kiln and the chemical nature of the
material being processed. In cement, maintaining a coating of the processed material
on the refractory surface prolongs the refractory life. The thickness of the lining is
generally in the range 80 to 300 mm. A typical refractory will be capable of

maintaining a temperature drop of 1000°C or more between its hot and cold faces.
The shell temperature needs to be maintained below around 350°C in order to protect
the steel from damage, and continuous infrared scanners are used to give early
warning of "hot-spots" indicative of refractory failure.
 Tyres and Rollers
Tyres, sometimes called riding rings, usually consist of a single annular steel casting,
machined to a smooth cylindrical surface, which attach loosely to the kiln shell
through a variety of "chair" arrangements. These require some ingenuity of design,
since the Tyre must fit the shell snugly, but also allow thermal movement. The Tyre
rides on pairs of steel rollers, also machined to a smooth cylindrical surface, and set
about half a kiln-diameter apart. The rollers must support the kiln, and allow rotation
that is as nearly frictionless as possible. A well-engineered kiln, when the power is cut
off, will swing pendulum-like many times before coming to rest. The mass of a
typical 6 x 60 m kiln, including refractories and feed, is around 1100 tones, and would
be carried on three Tyres and sets of rollers, spaced along the length of the kiln. The
longest kilns may have 8 sets of rollers, while very short kilns may have only two.
Kilns usually rotate at 0.5 to 2 rpm, but sometimes as fast as 5 rpm. The Kilns of most
modern cement plants are running at 4 to 5 rpm. The bearings of the rollers must be
capable of withstanding the large static and live loads involved, and must be carefully
protected from the heat of the kiln and the ingress of dust. In addition to support
rollers, there are usually upper and lower "retaining (or thrust) rollers" bearing against
the side of Tyres, that prevent the kiln from slipping off the support rollers.
Figure 15: Tyres & Rollers Figure 16: Refractory Lining
 Drive Gear
The kiln is usually turned by means of a single Girth Gear surrounding a cooler part
of the kiln tube, but sometimes driven rollers turn it. The gear is connected through a
gear train to a variable-speed electric motor. This must have high starting torque in
order to start the kiln with a large eccentric load. A 6 x 60 m kiln requires around 800
kW to turn at 3 rpm. The speed of material flow through the kiln is proportional to
rotation speed, and so a variable speed drive is needed in order to control this. When
driving through rollers, hydraulic drives may be used. These have the advantage of
developing extremely high torque. In many processes, it is dangerous to allow a hot
kiln to stand still if the drive power fails. Temperature differences between the top

and bottom of the kiln may cause the kiln to warp, and refractory is damaged. It is
therefore normal to provide an auxiliary drive for use during power cuts. This may be
a small electric motor with an independent power supply, or a diesel engine. This
turns the kiln very slowly, but enough to prevent damage.
 Internal heat exchangers
Heat exchange in a rotary kiln may be by conduction, convection and radiation, in
descending order of efficiency. In low-temperature processes, and in the cooler parts
of long kilns lacking preheaters, the kiln is often furnished with internal heat
exchangers to encourage heat exchange between the gas and the feed. These may
consist of scoops or "lifters" that cascade the feed through the gas stream, or may be
metallic inserts that heat up in the upper part of the kiln, and impart the heat to the
feed as they dip below the feed surface as the kiln rotates. The latter are favored
where lifters would cause excessive dust pick-up. The most common heat exchanger
consists of chains hanging in curtains across the gas stream.
 Other equipment
The kiln connects with a material exit hood at the lower end and to ducts for waste
gases. This requires gas-tight seals at either end of the kiln. The exhaust gas may go
to waste, or may enter a preheater which further exchanges heat with the entering
feed. The gases must be drawn through the kiln, and the preheater if fitted, by a fan
situated at the exhaust end. In preheater installations, which may have a high
pressure-drop, a lot of fan power may be needed, and the fan is often then largest
drive in the kiln system. Exhaust gases contain dust and there may be undesirable
constituents such as sulfur dioxide or hydrogen chloride. Equipment is installed to
scrub these out before the exhaust gases pass to atmosphere, called ESP.
 Thermal efficiency
The thermal efficiency of the rotary kiln is about 50-65%.
 Principle of Operation
The kiln is a cylindrical vessel, inclined slightly to the horizontal, which is rotated
slowly about its axis. The material to be processed is fed into the upper end of the
cylinder. As the kiln rotates, material gradually moves down towards the lower end,
and may undergo a certain amount of stirring and mixing. Hot gases pass along the
kiln, sometimes in the same direction as the process material (co-current), but usually
in the opposite direction (counter-current). The hot gases may be generated in an
external furnace, or may be generated by a flame inside the kiln. Such a flame is
projected from a burner-pipe (or "firing pipe"), which acts like a large Bunsen burner.
The fuel for this may be gas, oil, pulverized petroleum coke or pulverized coal.
Here, at DCM SCW the kiln is 120 m long, it has a diameter of 3.75 m. it is longer
than usual because it’s a wet process and additional chain zone required to bring the
moisture down. The chain zone is about 23.75 m in length. The speed of kiln is varied

by a D.C drive. Kiln is coal fired and the flue gases travel up the kiln. These flue
gases then passes through the ESP (electrostatic precipitator) where dust is collected
and cleaned flue gases are pulled out of the system by an I.D fan which is again
driven by a variable speed motor. The dust is again put into the decanter from where it
goes again to the normal procedures of raw preparation
As the raw mix travel down the kiln it follows the helical path from chain zone. After
chain zone comes the preheating zone where the raw mix components are heated up
to the calcination temperature. A calcination zone where the raw mix gets calcinated
follows this. CO2 released .the calcination zone terminates into burning zone where
heat released through coal burning melt the oxide an bring them to react to clinker
.the fine coal, which is used to create the flame is provided by coal mill. The length
and temperature of various zone in kiln vary with the firing rate, feed rate and the I.D
fan speed .the burning zone temperature is 1250°C-1400°C
Different reactions at different temperatures are given below in table:
Temperatures Reactions
180c Evaporation of water
500c and above Evolution of combined gases
900c and above Clinkerization and dehydration
1200c Production of clay and production of CO2
1200c and above Reaction between clay and lime and thus forms the
cement compound
Electrostatic precipitator (ESP)

An electrostatic precipitator (ESP) is a filtration device that removes fine particles,
like dust and smoke, from a flowing gas using the force of an induced electrostatic
charge minimally impeding the flow of gases through the unit. In contrast to wet
scrubbers, which apply energy directly to the flowing fluid medium, an ESP applies
energy only to the particulate matter being collected and therefore is very efficient in
its consumption of energy (in the form of electricity).
The most basic precipitator contains a row of thin vertical wires, and followed by a
stack of large flat metal plates oriented vertically, with the plates typically spaced
about 1 cm to 18 cm apart, depending on the application. The air or gas stream flows
horizontally through the spaces between the wires, and then passes through the stack
of plates. A negative voltage of several thousand volts is applied between wire and
plate. If the applied voltage is high enough, an electric corona discharge ionizes the
gas around the electrodes. Negative ions flow to the plates and charge the gas-flow
particles. The ionized particles, following the negative electric field created by the
power supply, move to the grounded plates. Particles build up on the collection plates
and form a layer. The layer does not collapse, thanks to electrostatic pressure (due to
layer resistivity, electric field, and current flowing in the collected layer).
Figure 17: Working of ESP

 Collectionefficiency
Precipitator performance is very sensitive to two particulate properties:

1) Electrical resistivity; and
2) Particle size distribution.
These properties can be measured economically and accurately in the laboratory,
using standard tests. Resistivity can be determined as a function of temperature in
accordance with IEEE Standard 548. This test is conducted in an air environment
containing a specified moisture concentration. The test is run as a function of
ascending or descending temperature, or both. Data is acquired using an average ash
layer [further explanation needed] electric field of 4 kV/cm. Since relatively low
applied voltage is used and no sulfuric acid vapor is present in the test environment,
the values obtained indicate the maximum ash resistivity.
In an ESP, where particle charging and discharging are key functions, resistivity is an
important factor that significantly affects collection efficiency. While resistivity is an
important phenomenon in the inter-electrode region where most particle charging
takes place, it has a particularly important effect on the dust layer at the collection
electrode where discharging occurs. Particles that exhibit high resistivity are difficult
to charge. But once charged, they do not readily give up their acquired charge on
arrival at the collection electrode. On the other hand, particles with low resistivity
easily become charged and readily release their charge to the grounded collection
plate. Both extremes in resistivity impede the efficient functioning of ESPs. ESPs
work best under normal resistivity conditions.
 Advantages of ESP
 High collection efficiency.
 Low resistance path for gas flow
 Treatment of large amount of gases and at high temperature
 Ability of coping with corrosive atmosphere

Clinker cooler and coal section
The clinker due to rotary of the kiln gets discharged into the grate cooler where
clinker is cooled. There are four sections of grate cooler. in first section ,moving
clinker bed is cooled with the fresh air is forced through the grate cooler fan no.1 . In
second and third section, the clinker is cooled with the help of circulation air through
fan no. 2&3. Finally the cooled clinker is about 100c. This is then feed into VSI
crusher where it is broken into small pieces. From here small pieces are fed into the
drag chain, which fall onto the deep where it is stored into the cement silos.
 VSI (Vertical shaft impact) crusher:
VSI crushers use a different approach involving a high-speed rotor with wear resistant
tips and a crushing chamber designed to 'throw' the rock against. The VSI crushers
utilize velocity rather than surface force as the predominant force to break clinker.
Applying surface force (pressure) results in unpredictable and typically non-cubical
resulting particles. Utilizing velocity rather than surface force allows the breaking
force to be applied evenly both across the surface of the clinker.
VSI crushers generally utilize a high speed-spinning rotor at the center of the crushing
chamber and an outer impact surface of either abrasive resistant metal anvils or
crushed rock. Utilizing cast metal surfaces 'anvils' is traditionally referred to as a
"Shoe and Anvil VSI".
Figure 18:VSI
 Cement Silos
Cement silos are on-site storage containers used for the storage and distribution of
various types of cement mixtures. A cement silo can be a permanent structure, or a
portable model that can be relocated when necessary. The cement silo usually is

equipped with some type of blower to help expel the stored contents into a truck or
other receptacle.
A cement storage silo can be structured to hold no more than a few tons of dry cement
products, or be designed to efficiently hold several hundred tons. Generally, larger
silos are permanent structures that cannot be moved. It is used, where the finished
product is stored until it is time for shipment. Many building sites that utilize concrete
in the construction process opt for portable cement silos that can be moved around the
site as the need arises.
It is not unusual for construction companies to keep several portable cement silos
available for different building projects. These simple storage devices can usually be
set up in a matter of hours, and then dismantled once the project is complete. Storage
of the portable cement silo is relatively easy, since the components can be stored in a
Warehouse until the device is needed at another building site.
Both the permanent and the portable cement silo are usually equipped with some type
of blower. The blower makes it easier to expel the product from the silo. Blowers are
often driven by electricity, although there are models that rely on propane or even
gasoline. Blower equipment with the portable silos takes very little time to set up, and
can also be stored easily when not in use.
It is important to note that the materials and the design of a cement silo will vary,
depending on the type of cement product that is to be stored in the facility. Not all
types of building materials are conducive to keeping all of the various components
that go into cement blends from caking or absorbing moisture. For example, a silo
that is structured to protect the integrity of soda ash may not work as well with lime.
Along with the ingredients of the concrete, the configuration of the cement silo will
be slightly different for products that are identified as high performance concrete or
self-compacting concrete.
There are two cement silos, one for POC and other one for PPC and one steel silo for
steel grade cement. The cement silos have a capacity of 3500 metric ton each and
steel silo is having 700 metric ton capacity.
Figure 19: Silo

Cement mill
A cement mill is the equipment used to grind the hard, nodular clinker from the
cement kiln into the fine grey powder that is cement. Most cement is currently ground
in ball mills and also vertical roller mills, which are more effective than ball mills.
Clinker from the silos is extracted from the bottom through three vibro feeders
installed in each silos. The clinker belt with a constant speed feed the clinker into
cement mill.
For OPC, gypsum is added and for PPC, pozzolona is added. The feeding of cement
mill is done through weight feeder. Gypsum from yard is fed into a hopper through a
conveyer belt into pozzolona bins by diverting the material with the help of
hydraulically operated diverter. Here, the ball mill is filled with grinding media
varying from 100mm-150mm sizes in first chamber and in second compartment
cylindrical pebbles clypeus of 20mm-25mm.
 Materials ground
Portland clinker is the main constituent of most cement. In Portland cement, a little
calcium sulfate (typically 3-10%) is added in order to retard the hydration of
tricalcium aluminate. The calcium sulfate may consist of natural gypsum, anhydrite,
or synthetic wastes such as flue-gas desulfurization gypsum. In addition, up to 5%
calcium carbonate and up to 1% of other minerals may be added.
It is normal to add a certain amount of water, and small quantities of organic grinding
aids and performance enhancers. "Blended cements" and Masonry cements may
include large additions (up to 40%) of natural pozzolans, fly ash, limestone, silica
fume or metakaolin. Blast furnace slag cement may include up to 70% ground
granulated blast furnace slag.
Gypsum and calcium carbonate are relatively soft minerals, and rapidly grind to ultra-
fine particles. Grinding aids are typically chemicals added at a rate of 0.01-0.03% that
coat the newly formed surfaces of broken mineral particles and prevent re-
agglomeration. They include 1,2-propanediol, acetic acid, triethanolamine and
lignosulfonates.
 Temperature control
Heat generated in the grinding process causes gypsum (CaSO4 .2H 2O) to lose water,
forming bassanite (CaSO4 .0.2-0.7H 2 O) or γ-anhydrite (CaSO4. ~0.05H2O). The
latter minerals are rapidly soluble, and about 2% of these in cement is needed to
control tricalcium aluminate hydration. If more than this amount forms, crystallization
of gypsum on their re-hydration causes "false set" - a sudden thickening of the cement
mix a few minutes after mixing, which thins out on re-mixing.
High milling temperature causes this. On the other hand, if milling temperature is too
low, insufficient rapidly soluble sulfate is available and this causes "flash set" - an

irreversible stiffening of the mix. Obtaining the optimum amount of rapidly soluble
sulfate requires milling with a mill exit temperature within a few degrees of 115 °C.
Where the milling system is too hot, some manufacturers use 2.5% gypsum and the
remaining calcium sulfate as natural α-anhydrite (CaSO4).
Complete dehydration of this mixture yields the optimum 2% γ-anhydrite. In the case
of some efficient modern mills, insufficient heat is generated. This is corrected by
recirculating part of the hot exhaust air to the mill inlet.

Packaging plant
Packing of cement is done by L&T rotatory packing machine .the cement is extracted
from the selected silos and through slides; cement is taken into bucket elevator and
subsequently to the hopper just above the packer. There are two packing machines for
the emergency case.
Rotatory packing machine is packing machine developed against influence of cement
impurities in open circuit mill on packing. it has overcome the problems such as poor
measurement and serious ash leakage of shutter in mechanized kiln for controlling ash
discharge .it completes the procedures of ash discharge and stopping through using
electromagnetic valves and air cylinder to control the loosening and closing of rubber
hose ,and thereby reduces the maintenance cost and thoroughly solve the problem of
large packing dust.
It is a impeller filling machine, with stable performance, easy operation, reasonable
structure and convenient maintenance .it can realize the packing of cement without
need of pneumatic components .it thoroughly solves the problem of ash leakage and
extruding gate plate. Its outstanding advantage are energy saving and environment
protection. Replacement rate of spare is remarkably reduced. Maintenance cost is also
reduced. Therefore, it is widely accepted by vast users.
Figure 20: Packaging Machine

Quality control
There is a laboratory setup to continuously monitor the quality of cement, parameters
of, which are defined as under:
In addition to control of temperature (mentioned above), the main requirement is to
obtain a consistent fineness of the product. From the earliest times, fineness was
measured by sieving the cement. As cements have become finer, the use of sieves is
less applicable, but the amount retained on a 45-μm sieve is still measured, usually by
air-jet sieving or wet sieving. The amount passing this sieve (typically 95% in modern
general-purpose cements) is related to the overall strength-development potential of
the cement, because the larger particles are essentially unreactive.
The main measure of fineness today is specific surface. Because cement particles
react with water at their surface, the specific surface area is directly related to the
cement's initial reactivity. By adjusting the fineness of grind, the manufacture can
produce a range of products from a single clinker. Tight control of fineness is
necessary in order to obtain cement with the desired consistent day-to-day
performance, so round-the-clock measurements are made on the cement as it is
produced, and mill feed-rates and separator settings are adjusted to maintain constant
specific surface.
A more comprehensive picture of fineness is given by particle size analysis, yielding
a measure of the amount of each size range present, from sub-micrometer upwards.
This used to be mainly a research tool, but with the advent of cheap, industrialized
laser-diffraction analyzers, its use for routine control is becoming more frequent. This
may take the form of a desk-top analyzer fed with automatically gathered samples in a
robotized laboratory, or, increasingly commonly, instruments attached directly to the
output ducts of the mill. In either case, the results can be fed directly into the mill
control system, allowing complete automation of fineness control.
In addition to fineness, added materials in the cement must be controlled. In the case
of gypsum addition, the material used is frequently of variable quality, and it is
normal practice to measure the sulfate content of the cement regularly, typically by x-
ray fluorescence, using the results to adjust the gypsum feed rate. Again, this process
is often completely automated. Similar measurement and control protocols are applied
to other materials added, such as limestone, slag and fly ash.

Conclusion
The practical training has proved to be quite fruitful .It provided me to encounter with
such huge machines and mechanisms. It has allowed me an opportunity to get an
exposure of practical aspects and their implementation to theoretical fundamentals.
I became Familiarize with the practical engineering work in various disciplines and
methods of engineering practice. This will help me improving my performance in
theory classes by introducing to the practical work. It helped me to know my strengths
and weaknesses so that I can improve my skills and overcome my limitations by
taking appropriate measures I was exposed to real work situations and I learned how
to equip them with the necessary skills so that I would be ready for the job when I’ll
be graduated.
The architecture of the plant, the way various units are linked, the way of working in
plant and how everything is controlled make me realize that engineering is not just
learning the structured description and working of various machines but the greater
part of planning management

Report on Cement manufacturing process

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