Lucky cement internship report

•Syed Asim Ali Shah
•Internee
•140810
•Production
Name
Designation
Code
Department
•M Armaghan Aized ( Deputy General Manager, HR )
•10/06/2015
Submitted to
Date of submission

INTERNSHIP REPORT (LUCKY CEMENT LIMITED)
2
S.NO. TOPICS PAGE NO.
1 Acknowledgement 3
2 Executive summary 4
3 Introduction & history 5
4 Beginning of cement 7 to 8
5 Type of cements 8 to 9
6 Methods of cement manufacturing 9to 10
7 Setting of cement 10 to 11
8 Different cement manufacturing& machinery and equipments 11 to 12
9 Grinding laws 12
10 Hammer crusher 14
11 Conveying equipments 15
12 Stacker and reclaimer 16
13 Vertical roller mills (raw mill and coal mill) 15 to 16
14 Blending silo 16
15 cyclone 17
16 Suspension pre heater tower 17 to 18
18 Rotatory kiln 19 to 22
17 Reciprocating grate coolers 23
18 Cement mill 24
19 Bag house 25 to 26
20 Conclusion 27
21 References 27

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ACKNOWLEDGEMENT
All praises belong to almighty ALLAH who is the supreme Authority Knowing the ultimate
relations underlying all sorts of phenomenon going on in this universe and whose blessings and
exaltation flourished my thoughts and thrived my ambitions to have the cherished fruit of my
humblest thanks to the Holy Prophet Hazrat Muhammad (Peace be upon him) who is forever a
torch of guidance and knowledge and knowledge for humanity as a whole.
I deem it my utmost pleasure to avail this opportunity to express gratitude and deep sense of
obligation to my reverend teachers, for their valuable and dexterous guidance, scholarly
criticism, untiring help, compassionate attitude, kind behavior, moral support and enlightened
supervision during the whole study and completion of the project.
I am also gratitude to staff of Lucky Cement Limited. Especially
Ahmad Ali Shah (Senior Deputy Manager), Syed Nazim Ali Shah (Trainee Engineer),
Muhammad Ali (Trainee Engineer), Mohsin (Trainee Engineer).
Who provides me useful information during the internship program. I am thankful to all those
people, who provide me valuable information.
Finally, I should like to extend heartfelt thanks to my adoring PARENTS, for their day and night
prayers, sacrifices, encouragement, moral and financial support throughout the course of my
study.
Syed Asim Ali Shah
B.E. (Chemical Engineering) INPROGRESS

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EXECUTIVE SUMMARY
This report is based on the activities performed during the internship at Lucky Cement Limited.
Internship duration was 12 days and it provided practical knowledge of working in professional
environment. This learning experience is described in detail in the various sections of this report.
In the first section, there is some detail about the company. The history and present status of the
company is explained. The organization structure and the details of its management along with
its location are also discussed. I have also discussed the operations, process and machine use in
cement manufacturing.
The second section provides information about the activities that I performed during the
internship. I worked as an internee mainly in production department.
The third and last section includes the conclusion.

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INTRODUCTION & HISTROY
Yunus Brothers Group is one of the largest export houses of Pakistan, Lucky
Cement Limited currently has the capacity of producing 25,000 tons per day of Dry
Process Cement.
Lucky Cement Limited (LCL) is one of the largest producers and leading exporters
of quality cement in Pakistan, with a production capacity of 7.75 million tons per
annum. The company is listed on Karachi, Lahore, Islamabad and London Stock
Exchanges.
Over the years, the Company has grown substantially and is expanding its business
operations with production facilities at strategic locations in Karachi to cater to the
Southern regions, Pezu and Khyber Pakhtunkhwa to furnish the Northern areas of
the country. Lucky Cement is Pakistan’s first company to export sizeable quantities
of loose cement being the only cement manufacturer to have its own loading and
storage terminal at Karachi Port.
Lucky Cement Limited has embarked on the journey of global expansion by setting
up cement grinding facility in Basra, Iraq and a cement manufacturing plant in
Democratic Republic of Congo (DRC). Furthermore, the company has diversified
into power generation by investing in a 660 MW coal-based power project in
Karachi. Also the acquisition of ICI Pakistan is another noteworthy move towards
the expansion of Lucky Cement’s industry portfolio.
Lucky Cement is an ISO 9001:2008 and 14001:2004 certified company and also
possesses many other international certifications including Bureau of Indian
Standards, Sri Lankan Standard Institute, Standards Organization of Nigeria, Kenya
Bureau of Standards and South African Bureau of Standards.

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OVERALL CEMENT MANUFACTURING PROCESS

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BEGINNING OF CEMENT
A cement is a binder, a substance that sets and hardens and can bind other materials together.
The word "cement" traces to the Romans, who used the termopus caementicium to
describe masonry resembling modern concrete that was made from crushed rock with burnt
lime as binder. The volcanic ash and pulverized brick supplements that were added to the burnt
lime, to obtain a hydraulic binder, were later referred to as cementum, cimentum and cement.
Cements used in construction can be characterized as being either hydraulic non-hydraulic,
depending upon the ability of the cement to be used in the presence of water (see hydraulic and
non-hydraulic lime plaster).
Non-hydraulic cement will not set in wet conditions or underwater, rather it sets as it dries and
reacts with carbon dioxide in the air. It can be attacked by some aggressive chemicals after
setting.
Hydraulic cement is made by replacing some of the cement in a mix with activated aluminium
silicates, pozzolanas, such as fly ash. The chemical reaction results in hydrates that are not very
water-soluble and so are quite durable in water and safe from chemical attack. This allows
setting in wet condition or underwater and further protects the hardened material from chemical
attack (e.g., Portland cement).

8
The chemical process for hydraulic cement found by ancient Romans used volcanic ash
(activated aluminium silicates). Presently cheaper than volcanic ash, fly ash from power stations
recovered as a pollution control measure or other waste or by products are used as pozzolanas
with plain cement to produce hydraulic cement. Pozzolanas can constitute up to 40% of Portland
cement.
The most important uses of cement are as a component in the production of mortar in masonry,
and of concrete, a combination of cement and an aggregate to form a strong building material.
Table below shows different types of cement, their composition and uses:
Types of
Cement
Composition Purpose
Quick setting
cement
Small percentage of aluminium
sulphate as an accelerator and reducing
percentage of Gypsum with fine
grinding
Used in works is to be completed in
very short period and concreting in
static and running water
Low Heat
Cement
Manufactured by reducing tri-calcium
aluminate
It is used in massive concrete
construction like gravity dams
Sulphates
resisting
Cement
It is prepared by maintaining the
percentage of tricalcium aluminate
below 6% which increases power
against sulphates
It is used in construction exposed to
severe sulphate action by water and
soil in places like canals linings,
culverts, retaining walls, siphons
etc.,
Blast Furnace
Slag Cement
It is obtained by grinding the clinkers
with about 60% slag and resembles
more or less in properties of Portland
cement
It can used for works economic
considerations is predominant.
High Alumina
Cement
It is obtained by melting mixture of
bauxite and lime and grinding with the
clinker it is rapid hardening cement
with initial and final setting time of
about 3.5 and 5 hours respectively
It is used in works where concrete is
subjected to high temperatures,
frost, and acidic action.
White Cement It is prepared from raw materials free
from Iron oxide.
It is more costly and is used for
architectural purposes such as pre-
cast curtain wall and facing panels,
terrazzo surface etc.,
Colored cement It is produced by mixing mineral
pigments with ordinary cement.
They are widely used for decorative
works in floors
Pozzolanic
Cement
It is prepared by grinding pozzolanic
clinker with Portland cement
It is used in marine structures,
sewage works, sewage works and
for laying concrete under water such

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as bridges, piers, dams etc.,
Air Entraining
Cement
It is produced by adding indigenous air
entraining agents such as resins, glues,
sodium salts of Sulphates etc during the
grinding of clinker.
This type of cement is specially
suited to improve the workability
with smaller water cement ratio and
to improve frost resistance of
concrete.
Hydrographic
cement
It is prepared by mixing water repelling
chemicals
This cement has high workability
and strength
CEMENT MANUFACTURING PROCESS
1) Quarry (The raw material that is used to manufacture cement mainly limestone blasted
from the quarry.)
2) Grinding (Primary: Hammer Crusher & Secondary: VRM or Ball mill)
3) Storage (silo)
4) Burning (Pre- heater and kiln)
5) Clinker storage yard
6) Grinding (Ball mill or OK mill)
7) Storage (silo)
8) Packing
9) Dispatch
METHODS OF CEMENT MANUFACTURING
I. Wet process: Grinding and mixing of the raw materials in the Existence of water.
II. Dry process: Grinding and mixing of the raw materials in their dry state.
DIFFERENCE BETWEEN WET AND DRY PROCESS
S.No Wet process Dry process
1
Moisture content of the slurry is 35-
50%.
Moisture content of the pellets is 12%.
2
Size of the kiln needed to manufacture
the cement is bigger.
Size of the kiln needed to manufacture
the cement is smaller.

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3
The amount of heat required is higher,
so the required fuel amount is higher.
The amount of heat required is lower, so
the required fuel amount is lower.
4 Less economically. More economically.
5
The raw materials can be mix easily, so
a better homogeneous material can be
obtained.
Difficult to control the mixing of raw
materials process, so it is difficult to
obtain homogeneous material.
6
The machinery and equipments do not
need much maintenance.
The machinery and equipments need
more maintenance.
SETTING OF CEMENT
When mixed with water, cement sets to a hard mass. It first forms a plastic mass which hardens
after some time due to 3-dimensional cross-links between the --Si-O-Si-- and --Si-O-Al-- chains.
The first setting occurs within 24 hours whereas the subsequent hardening requires a fortnight,
when it is covered by a layer of water. This transition from plastic to solid state is called setting.
REACTIONS INVOLVED IN SETTING OF CEMENT
∑ On hydration silicates and aluminates of calcium get converted to their respective hydrated
colloidal gels.
At the same time, hydrolysis precipitates calcium hydroxide and aluminium hydroxide.

11
This calcium hydroxide binds calcium silicate particles together. On the other hand, aluminium
hydroxide fills the interstices (an intervening space) rendering the mass impervious (not
affording passage to a fluid).
Role of gypsum - Gypsum reacts with tricalcium aluminate.
Note: The fast-setting tricalcium aluminate is removed to slow down the setting process. A quick
setting will give rise to crystalline hydrated calcium aluminate. A slower setting yields the
colloidal gel that imparts greater strength to the set mass. Thus gypsum helps in regulating the
setting time of cement.
DIFFERENT CEMENT MANUFACTURING MACHINERY AND EQUIPMENTS
Crushers Jaw, Hammer, Roll and Impact, mobile and semi mobile Crushers.
Mills
Ball and tube mills - mills with slide shoe bearings; Vertical ring and
roller mills; Roller press and ball mill combinations; Horizontal
Roller mill
Classifiers
Wet classifiers; Dry c1assifiers- grit separators, mechanical air
separators; High efficiency separators
Blending
Slurry blending - slurry mixer; Air merge blending - batch and
continuous
Preheaters
Calciners in wet kilns, traveling grate preheaters; Suspension
preheaters 4 - 6 stages.
Calciners in and off line; spouted bed, fluidized bed and many others

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Kilns
Shaft kiln-Rotary Kiln - Wet - Long dry - Short - Semi dry and Dry
pre heater kilns
Coolers
Rotary Cooler - planetary cooler; Traveling and Reciprocating grate
coolers; Static grate, pendulum coolers and cross bar coolers
Dust collectors
Cyclones; poly and multiclones; Bag filters- glass bag filters;
Gravel Bed filters; Electrostatic PreCipitators
Packing
machines
Stationary - rotary - rotary electronic
Despatches
Mechanized-automated loading of bagged cement; Bulk cement by
road and rail and sea
GRINDING LAWS
WALKAR’S LAW
Walker proposed a generalized differential form of the energy-size relationship:
dE/dD = -kDn
where E = amount of energy (work done) required to produce a change per unit mass
D = size of unit mass
K = Constant
n = constant
For n = -1.0 Walker equation becomes Kick’s theory used for coarse particles > 1 mm.
For n = -1.5 Walker equation becomes Bond’s theory. This theory is used when neither Kick’s nor
Rittinger’s law is applicable.
For n = -2.0 Walker equation becomes Rittinger’s theory used for fine particles < 1 mm size.
RITTINGER’S LAW
The energy expended during comminuting is proportional to the area of the new surface
produced as a result of particle fragmentation.
dE/dD = -kDn
put n= -2

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After integration
E= kr (1/Dout – 1/Din)
KICK’S LAW
The energy is proportional to the size reduction ratio.
dE/dD = -kDn
put n= -1
After integration
E= kk ln(Din /Dout)
BOND’S LAW OR UNIVERSAL LAW
The total work input represented by a given weight of crushed or ground product is inversely
proportional to the square root of the diameter of the product particles.
dE/dD = -kDn
put n= -3/2
After integration
E= kb (1/Dout
1/2
– 1/Din
1/2
)
If the coming mass of particle is infinite
E= kb / Dout
1/2
HAMMER CRASHER
A hammer mill is a crusher that can grind, pulverize, and crush
a wide range of materials. This crusher employs a rain of
hammer blows to shatter and disintegrate the material. Hammer
mills produce a finish product size that is dependent upon...
∑ Openings in perforated screens or grate bars
∑ Number, size and type of hammers
∑ Grinding plate setting
∑ Rotor speed
PROCESS DIAGRAM

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Conveyor system
A conveyor system is a common piece of mechanical handling equipment that moves materials
from one location to another. Conveyors are especially useful in applications involving the
transportation of heavy or bulky materials. Conveyor systems allow quick and efficient transportation
for a wide variety of materials,
PROPORTION AREA (PRE HOMOGENIZATION AREA)
STACKER RECLAIMER SYSTEMS
Stacker Rec1aimer Systems are storage and extraction systems for crushed and granular
materials like crushed limestone and coal. They can handle material at high rates of feed and
extraction because conveyors in the systems are belt conveyors. Materials are stored as triangular

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stock piles. Quantity to be stored is determined by the stocks to be maintained in number of days'
consumption. 3.2 Types of Stock Piles There are either two linear stock piles- arranged side by
side or in line; or a circular stock pile.
STACKER RECLAIMER SYSTEMS
1. Circular piles are generally used for coal because capacities and handling rates are small.
2. Stacker It receives crushed stone / coal from the crusher. It consists of a movable carriage
which moves on rails along the proposed stock piles.
3. Stacker belt goes over this movable carriage and drops material it is carrying on a cross belt
which reaches up to the center of the stock pile and which can slew upward and downwards
pivoted at the feeding end.
4. Material is dropped from this belt as the main belt moves at a predetermined rate along the
pile. Pile thus gets built up in layer.
ADVANTAGE FOR BOTH LIMESTONE AND COAL.
1. It is use to mix the compounds in fix proportion.
2. With the help of X-Ray analyser it should be possible to monitor composition of limestone
extracted by feeding stone from different sectors of mines to crusher.
SEVERAL DESIGNS OF STACKER RECLAINER SYSTEM
There are several designs of the Stacker - Rec1aimer systems and they can be 'tailor made' to suit
specific needs. Mostly two ways are two ways are use for reclaimer system
VERTICAL RING AND ROLLER IN CEMENT PLANT

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INTRODUCTION OF
VERTICAL ROLLER MILL
Vertical roller mill is a kind of ideal large grinding equipment, widely used in cement, electric
power, metallurgy, chemical industry, the gold ore, etc. It sets the crushing, drying, grinding,
sorting conveyor at an organic whole, high production efficiency, can be massive, granular and
powdered materials into powder material will be required. Feed particle size: the vertical roller
mill can handle strength between 38 to 55 mm material, production capacity can reach 10-50 t/h,
vertical roller mill for material’s ability to adapt is very strong, can be processing cement, coal,
feldspar, calcite, talc, fluorite, iron ore, copper ore, phosphate rock, graphite, quartz, slag and
other materials.
1. The raw material is finish-ground before being fed into the kiln for clinkering.
2. This grinding is done using either ball mills or vertical roller mills (VRM).
3. The choice between a ball mill and VRM is governed by many factors such as the moisture
content of the raw material, the size of the plant, the abrasiveness of the material, the energy
consumption levels, reliability, and finally financial consideration
4. VRM uses the compression principle to grind the raw material.
collecting conveyor
fresh feed
louvre ring
scraper
bucket elevator

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STORAGE
BULK STORAGE
Course material such as gravel and coal are stored outside in large piles, unprotected from
weather when hundred and thousand of materials involved, this is most economical method and
than they are conveyor toward process. Outdoor storage caused the leach and dust problem they
are controlled by covering the piles.
BIN STORAGE
Fine material cannot be stored outside because of environmental pollution so they are stored in

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1. hopper
2. bine
3. Silo
They are either cylindrical or rectangular vassal. A silo is relatively tall and bin are not so tall
and usually fairly wide. A hopper is the small vassal with sloppy bottom, for temporary storage
before feeding in the process all these container are loaded from top by a kind of elevator and
discharge material from bottom.
BLENDING SILO
In order to blend and homogenize the raw materials properly, continuous
blending silos are used.
The blending silo can store 6000 tons of the powder mixture.
It is highly insulated so that it can maintain the appropriate temperature of
the powder mixture.
SEPARATORS
1. Wet scraper
2. Dry scraper
I. Bag house (by precipitating particles)
II. Cyclone (by centrifugation)
DRY SCRAPER
I. BAG HOUSES
A bag house (B/H), aka fabric filter, is a particular air pollution control device, used in similar
applications as electrostatic precipitators. In the 1970s, introduction of fabrics capable of
withstanding high temperatures (> 350 degrees Fahrenheit) made bag houses practical for use in
electrical generation and industrial processes. Bag houses are highly efficient particulate
collection devices, regardless of the incoming dust loading or particle size. Bag houses also offer
adaptability as dry collection devices using absorbents for removing gases and heavy metals.
WORKING PRINCIPLE
Making use of the pressure of gas which inside and outside of dust bags, the gas through the bag
into cleaning gas, and dust left on the bag surface. With the increase of dust on the bag surface,
the filtration resistance will increase according to the time controlled procedures injection system
will make use of certain pressure and flow of air to clear the surface dust of each bag.

19
TYPES OF BAG HOUSES
Bag houses are classified by cleaning method. Three types of bag houses predominate in the
U.S.: reverse air (gas cleaning), pulse jet (compressed air cleaning) and shaker.
REVERSE AIR (R/A)
R/A bag houses are compartmentalized so bags can be cleaned off-line
by stopping the dirty gas flow and backwashing the compartment with
low pressure air from a separate fan. Cleaning action is very gentle,
which lengthens bag life. Dust collects on the inside of the bags. The
bags are held taut by tension springs at the top, and have anti-collapse
rings sewn into them to prevent packing during cleaning.
Components of a reverse air bag house:
1. Isolation dampers
2. Filter bag tensioning system
3. Anti-collapse rings on bags
4. Reverse air fan
PULSE JET (P/J)
In this type of bag house, a high pressure jet of air is used to remove
dust from bags supported by rings or metal cages. Bags in a P/J bag
house can be cleaned on-line. Dust collects on the outside of the
bags.This bag houses (round with an automated, rotating arm to
distribute compressed air row-by-row) are a type of P/J fabric filter.
1. Components of a pulse jet bag house:
2. Compressed air source
3. Compressed air storage header
4. Solenoid valve
5. Diaphragm valve
6. Blowpipe
SHAKER
Cleaning shaker bag houses takes considerably more energy and more
time than other designs, so they’re used less often than R/A or P/J. Like
R/A, the compartments of a shaker bag house must be cleaned off-line.

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1. Components of a shaker bag house:
2. Attachments for top and bottom of each bag
3. Movable frame from which bags are hung
4. Shaft and rod attached to external motor
¸ CLEANING SEQUENCES FOR BAG HOUSES
Bag houses are cleaned using one of the following sequences, depending on type.
INTERMITTENT: This cleaning sequence is used for single compartment bag houses, usually
shaker types. The fan/process must be stopped while the bags are cleaned.
CONTINUOUS OFFLINE: This cleaning sequence is used with multiple-compartment reverse air
or pulse jet bag houses. Each compartment is taken offline in turn to clean; the overall process is
not shut down during cleaning.
CONTINUOUS ONLINE: This fully automated cleaning sequence is typically used for pulse jet
bag hoses. The process flow continues during cleaning.
II. CYCLONES:
Cyclonic separation is a method of removing particulates from an air, gas
or liquid stream, without the use of filters,
through vortex separation. Rotational effects and gravity are used to
fine droplets of liquid from a gaseous stream. A high speed rotating (air)
flow is established within a cylindrical or conical container called a cyclone
Air flows in a helical pattern, beginning at the top (wide end) of the cyclone
stream through the center of the cyclone and out the top. Larger (denser) particles in the rotating
stream have too much inertia to follow the tight curve of the stream, and strike the outside wall,
then fall to the bottom of the cyclone where they can be removed. In a conical system, as the
rotating flow moves towards the narrow end of the cyclone, the rotational radius of the stream is
reduced, thus separating smaller and smaller particles. The cyclone geometry, together with flow
rate, defines the cut point of the cyclone. This is the size of particle that will be removed from
the stream with 50% efficiency. Particles larger than the cut point will be removed with a greater
efficiency and smaller particles with a lower efficiency.

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DIP TUBE
Dip tube length and diameter are naturally one of the most important factors for the cyclone
design and I think you will face several operation problems if you run the kiln without cyclone-5
dip/ immersion tube, some of them are:
1. Poor separation efficiency of cyclone-5.
2. Too high dust circulation.
3. Higher pressure drops in the cyclone.
4. More gas consumption.
5. Instability of burning process.
SUSPENSION PRE HEATER TOWER
Energy savings can be achieved within certain limits to raw materials moisture by reducing the
temperature of the hot gas through heat recovery with an additional cyclone stage. The higher the
number of preheater cyclone stages is the lower is the temperature reduction potential for the gas.
A 6-stage preheater precalciner plant using fossil fuels shows raw gas temperatures of about 280
- 290 °C, a 5-stage preheater 310 - 320 °C, a 4-stage preheater 340 - 350 °C and a 3-stage
preheater (which is not very common) more than 500 °C. The addition of an extra pre-heater
step may reduce the amount of heat available for material drying in the raw mills and will also
increase the electricity consumption in the required fans. The addition of a cyclone stage is only
feasible, e.g. if the original design was very conservative, or high amounts of secondary fuels are
used, especially in the calciner.
1. The key component of the gas-suspension preheater is the cyclone.
2. A cyclone is a conical vessel into which a dust-bearing gas-stream is passed tangentially.
3. A very efficient heat exchange takes place the gas is efficiently cooled, hence producing
less waste of heat to the atmosphere, and the raw mix is efficiently heated.
4. This efficiency is further increased if a number of cyclones are connected in sequence.

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BENEFITS
1. The top stage can reach 97% settling efficiency
2. Pressure drop of the line, including a 5 stage preheater, is less than 50 mbar
3. Heat and energy consumption is reduced
4. Reduction of dust load to filter
5. Technical advantages
6. Overall design to achieve a very low pressure drop
7. High heat exchange efficiency
8. Large cone to avoid build-up
9. Fan power reduction
Lower cyclones are equipped with segmented dip tubes, which better resist to chemical corrosion
at high temperatures.
ROTATORY KILN
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.
Fuels that have been used for primary firing include coal, petroleum coke,heavy fuel oil, natural
gas, landfill off-gas and oil refinery flare gas. High carbon fuels such as coal are preferred for
kiln firing
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.

23
REACTIONS IN THE KILN
1. ~100°C→ free water evaporates.
2. ~150-350C°→ loosely bound water is lost from clay.
3. ~350-650°C→decomposition of clay→SiO2&Al2O3
4. ~600°C→decomposition of MgCO3→MgO&CO2 (evaporates)
5. ~900°C→decomposition of CaCO3→CaO&CO2 (evaporates)
6. ~1250-1280°C→liquid formation & start of compound formation.
7. ~1280°C→clinkering begins.
8. ~1400-1500°C→clinkering

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9. ~100°C→clinker leaves the kiln & falls into a cooler.
Sometimes the burning process of raw materials is performed in two stages: preheating upto
900°C & rotary kiln
PROCESS OF CLINKER PRODUCTION

25
COMPOUND COMPOSITION OF CLINKER
Oxides interact with eachother in the kiln to form more complex products (compounds).
Basically, the major compounds of P.C. can be listed as:
COMMON NAMES
CHEMICAL NAME CHEMICAL FORMULA ABBREVIATIONS
ALITE TRI CALCIUM SILICATE 3CAO.SIO2 C3S
BELITE
DI CALCIUM SILICATE 2CAO.SIO2 C2S
CELITE
TRI CALCIUM ALUMINATE 3CAO.AL2O3 C3A
BROWNMILLERITE
TETRA CALCIUM ALUMINO
FERRITE
4CAO.AL2O3.FE2O3 C4AF
STRENGTH, HEAT OF HYDRATION AND SETTING CONTRIBUTION

26
1. 1st
to 7th
day C3A > C3S > C4AlF > C2S
2. 1st
month C3A > C3S > C4AlF = C2S
3. 3rd
month C3A = C3S = C4AlF < C2S
4. 1st
year C2S > C3S >C3A = C4AlF
5. 2nd
year C2S > C3S > C4AlF > C3A
RECIPROCATING GRATE COOLERS
The essential characteristic of a grate cooler is a layer of clinker
spread on a more-or-less horizontal perforated grate, through
which cold air is 7 fans by the blower. This grate is made of steel,
and the cold air keeps it sufficiently cool to avoid melting or
burning. The direction of the cooling air is roughly at right angles
to the direction of movement of the clinker, and the cooler
functions as a cross-current heat exchanger. This mechanism is
inherently less efficient than a counter-current heat exchanger.
After passing clinker through cooler it’s temperature is dropped down to 200°C
It is easy to tap off exhaust hot air streams in desired temperature ranges for use in other
processes - e.g. the about 1000C high temperature air is the transfer to preheater precalciner
through tertiary air duct and remaining goes to boiler for turbine.
The cooler grate is composed of overlapping rows of perforated grate
plates. Half of the rows are fixed to the casing of the cooler and
alternate rows are carried on a movable frame to which help in
reciprocating movement of plate by which bed of clinker is pushed
forward. Fine clinker can fall though the grate holes, and so the under-
grate chamber contains drag-chain conveyor(s) to move the spillage to
the outlet end of the hammer crusher has been placed at the end of the
cooler.

27
CEMENT MILL
BALL MILLS
A Ball mill is a horizontal cylinder partly filled with steel balls (30-50%) that rotates on its axis.
feed in the at 60 degree slope and exit at 30 degree of slope The inner surface of the cylinder is
usually made up of abrasion resistant material such as manganese or high carbon steel, stoneware
like silica rock or rubber. Less wear take place with rubber lined mill. The coefficient of friction
between ball and cylinder is greater than steel and stone ware lining the ball therefore carried
further in contact with surface and thus drop on the feed with greater height and cause impact on
fed and crushed the fed and then ground by attrition between the balls.
Some mill (tube mill) is usually divided into at least two chambers the material flow axially
along the mill from one compartment to another when it’s size reduces to less than that of
perforations in the plate. It reduces size up to 25mm
The grinding media are usually made of high-chromium steel flint pebbles or zircon spheres
In first chamber large Ball diameter here is in the range 25–125 mm.
Media in the second chamber are typically in the range 15–40 mm although media down to
5 mm are sometimes encountered.
Ball mill with diameter 5 metres will turn at around 14 rpm at around 75% of critical speed (the
maximum speed if speed exceed from this centrifugation accord no crushing take place).

28
Nc = 1/2π √[g/(R-r)]
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
In wet grinding power consumption is 30% less than dry grinding. 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.
FACTOR INFLUENCE ON THE SIZE OF MATERIAL
1. Rate of feed: higher the rate of feed lesser the reduction in size.
2. The properties of the feed material: Less reduction for harder material
3. Weight of ball: Increase the weight increase the size reduction.
4. The diameter of the ball: Lesser the ball size grater the size reduction give (fine
product)
5. The slop of ball the slop of mill: Increase in the inlet material slope which increases the
capacity and reduces the retention time of crushing
6. The speed of rotation of the mill: neither lower the speed nor higher the speed in both
case reduce impact on feed thus reduce size reduction. Speed should be just lesser than
critical speed

29
CONCLUSION:
This internship was a useful experience. I have gained new knowledge, skills and met many new
people. I achieved several of my learning goals, got insight into professional practice and learn
practical knowledge. I really enjoy a lot while doing work over there. Supervisor, managers and workers of the
departmenthelpandguidemealot.
REFERENCES
http://www.cementkilns.co.uk/suspension_preheater_kilns.html
http://www.cementkilns.co.uk/dry_process.html
http://www.cementkilns.co.uk/cooler_grate.html
http://www.cementkilns.co.uk/precalciner_kilns.html
http://en.wikipedia.org/wiki/Baghouse
http://en.wikipedia.org/wiki/Lathe
http://en.wikipedia.org/wiki/Cement_mill
http://www.tapc.com.au/fabricfilter/whatis.html

Lucky cement internship report

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