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DEPARTMENT OF MECHANICAL ENGINEERING
MEHRAN UET JAMSHORO
TRAINING PERIOD: 22-06-2015 TO 30-06-2015
DATE OF SUBMISSION: 30-06-2015
PRESENTED BY:
Muhammad Anique (12ME117)
Internship Report
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ACKNOWLEDGEMENT
We feel immense pleasure to become a Trainee Internee of a huge and gigantic
complex which produces one of the best quality Cement in Pakistan. Mr. Uzair
from HR Department who welcomed us and gave presentation regarding the
Complexi.e. M/s Lucky cement. His presentation covered allaspects of the Factory
sections, his presentation wascomprehensive, hence we did not find any difficulty
while visiting the different areas of Complex. Mr. Azhar from Mechanical
Department given us proper schedule for the internship. He was so supportive
during our visit, he guided us for all the proper sections of mechanical at the
complex.
I further want to thanks the people which have been mentioned below for their
precioustime and knowledge about their particular area .They have been the key
individuals during our visit.
Mr. Wajid (Crusher Area)
• Mr.Asif (Kiln Area and Pyro Area)
Mr. Ashfaque Ahmed Khatri and Mr.Haris (vertical raw mill)
Mr. Ahmed Ali Shah and Mr. Munawer (Cement and Packing Plant)
Overall, We Are Thankful To All the Officers and Workers of Lucky Cement Ltd.
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Abstract:
This report is being submitted at the end of 10 days internship program with M/s
LUCKY CEMENT LTD. The report contains the knowledge of the different areas of
interest and the process being involved in the manufacturing of cement products.
This report has an overview of mechanism used during the working of tools and
equipments. As I belong to the mechanical department therefore I have attached
herewith pictures of machinery used in this gigantic complex.
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CONTENTS
1. CEMENT MANUFACTURING PROCESS
2. RAW MATERIAL USED
3. CRUSHER AREA
4. MECHANICAL CONVEYORS SYSTEM
5. VERTICAL RAW MILL
6. KILN
7. WASTAGE HEAT USED
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1. Cement Manufacturing Process:
The raw materials needed to produce cement (calcium carbonate, silica, alumina, and iron
ore) are generally extracted from limestone rock, chalk, shale, or clay. These raw
materials are won from the quarry by either extraction or blasting. The process for cement
manufacturing in Lucky Cement used is Dry Process.
These naturally occurring minerals are then crushed through a milling process. At
this stage, additional minerals are added to ensure the correct chemical composition for
making cement. These minerals can be obtained from the waste or by-products of other
industries, such as paper ash. Milling produces a fine powder, known as raw meal, which
is preheated and then sent to the kiln for further processing.
The kiln is at the heart of the manufacturing process. Once inside the kiln, the raw meal is
heated to around 1,500 degrees C. At this temperature, chemical reactions take place to
form cement clinker, which contains hydraulic calcium silicates.
In order to heat the materials to this very high temperature, a 2,000-degree C flame is
required, which can be produced through the use of fossil and waste-derived fuels. The
kiln itself is angled by 3 degrees to the horizontal to allow the material to pass through it,
over a period of 20 to 30 minutes.
A small amount of gypsum (3 percent to 5 percent) is added to the clinker to regulate how
the cement will set. The mixture is then very finely ground to obtain "pure cement."
During this phase, different mineral materials, called "additions," may be added alongside
the gypsum. Used in varying proportions, these additions, which are of natural or
industrial origin, give the cement specific properties, such as reduced permeability, greater
resistance to sulfates and aggressive environments, improved workability, or higher-
quality finishes.
Finally, the cement is stored in silos before being shipped in bulk or in bags to the sites
where it will be used.
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2. RAW MATERIAL USED :
i. Lime stone
Lime stone is a sedimentary rock which has the formula CaCO3. Lime stone is an
important stone for masonry and architecture work. It is the main component of cement.
ii. Bauxite
Bauxite is the important aluminum ore. Its consist largely of minerals gibbsite AL(OH) 3 ,
hematite the clay mineral kaolinite etc.
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iii. Clay
Clay is a naturally occurring material composed primarily of fine-grained minerals, which
show plasticity through a variable range of water content. and which can be hardened
when dried and/or fired. Clay deposits are mostly composed of clay minerals , minerals
which impart plasticity and harden when fired and/or dried, and variable amounts of water
trapped in the mineral structure by polar attraction
iv. Latrite
Latrite is redish brown color and it contains iron content ,.It is less harder than gypsum but
harder than limestone.
v. Gypsum
Gypsum (Ca SO4)It is obtained from the N.W.F.P and 5% is added with clinker obtained
from kiln in cement mill and then grinded to get cement. It is used for refreshness of
cement.
vi. Coal and tyre as afuel
In lucky cement industry coal is the major source of fuel, for this purpose coal is imported
from South Africa and indonesia. Lucky cement is also using scrap tyre as a fuel as
calorific value of polymer is very good.
3. Crusher Area
In lucky cement industry hammer crusher are used for crushing the limestone and coal.
Coal crusher is also used sometimes for crushing clay.
In lime stone crushing area first the big blocks limestone are dumped in a big hooper with
the help of truck. And from there the blocks are feed into the feed roller with the help of
an apron conveyor, is a type of conveyor made from individual apron plates that are linked
together with hinges on its underside, thus creating a looped carrying surface where
materials can be placed. It plays a vital part in cement industries by being used to move
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different heavy materials from one location to another. This type of conveyor is used to
deliver a large number of materials across several phases of production and is particularly
useful for transport of huge and heavy materials.
The work of apron feeder is to slows velocity of the material and to protect the hammer
and crusher from wear and tear. It has the vertical arrangement of belts and pulleys
because it absorbs shock and horizontal arrangement may cause slip in belt. It has the
toothed gear having sensors which is quiet helpful in stopping the feeder for the protection
of crusher.
i. CRUSHER MECHANISM:
The crusher for limestone consists of multiple discs welded or joint together by any other
means. Each disc has a five holes which contains shafts and each shaft contain 9 hammers
it means that hammer crusher has 45 hammers. A hammer crusher has the different
clearance are set between hammer and casing of crusher according to the requirement of
size of finish. Usually we have 50, 100, 150 mm clearance. This Crushing machine
reduces the size of large stones to approximate 25 mm to 35mm . From this the material is
transferred to way feeder and storage house. The material from crusher transfer to storage
house with the help of long belt of 400 m.
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ii. STACKER AND RECLAIMER MECHANISM
The Stacker can pile the material by moving 360 degree. There is a track for the motion of
stacker on which the stacker can move which is motor driven. The boom of the stacker has
the special mechanisms of slewing with the help of which it can move 360 degree.
Reclaimer has the harrows which has needles in order to feed he material to bucket
conveyor. Harrow of reclaimer are of two types one is hydraulic driven while the one has
motor and chain driven which is used for coal and clay.
Bucket conveyor has special type of conveyor which can move material in the conveyor to
weigh tower with the help of bucket like mild steel. It is motor driven.
iii. WEIGH FEEDER
In weigh feeder there are four materials from different conveyors are storing in hooper.
From there they are forwarded to chute which guide it to conveyor. The mixing of
limestone, clay bauxite and latrite is fixed so the rpm of motors are fixed according to
there fixed proportion. As lime stone is the basic and most used in percent in cement
hence its rpm are greater than the other three. Here motor are gear and couple motors and
wave conveyor are to protect loss of materials.
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4.MECHANICAL CONVEYOR SYSTEM
conveyor are basically a mechanical system used for the transporting of different
types of Raw material , manufactured material etc.
Basically two types of mechanical conveyors are used:
1. Belt conveyor
2. Apron conveyor
The system comprises of mechanical transportation of different materials used in
cement manufacturing . The process starts from the crushing area , where the
crushed material is being transported through belt conveyor .This conveyor drops
the material into hopers . After proper proportioning of material through weigh
feeder, the material again transported to Raw mill through belt conveyor.
Apron conveyor are used where maximum load is carried out. Mostly apron
conveyors are used in the crushers . when highly weighted load is dropped in the
hopers which was assigned with apron conveyor.
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5. RAW MILL AREA
Material from weigh feeder is than brought through conveyor to the raw mill. Before raw
mill the remaining course particles are also added in the conveyor before raw mill.
Vertical raw mill is the most important part of cement manufacturing. It has a table which
is motor driven having bevel gear box as the power is transmitted at 90 degree. In this the
setting of mill is in vertical position. In raw mill we only rotate the table on which
different numbers of rollers are placed which are not driven by any motor. When the table
rotates than due to centrifugal force all the material goes away from the center and it
grinds between the rollers and table. There is a layer of limestone intentionally present
between rollers and tables. The rollers are attached with hydraulic arms in order to absorb
the shock. They are attached to accumulator which supply the oil at right timing.
Above the raw mill there is a fan called classifier is used in order to suck the fine particles
and to ensure no heavy particle can goes upward and if there is course particles collide
with the fan blade than it turn it back to raw mill. It has special heat treated blades as the
shock load of course particles may damage the blades. There is a rotary valve at the inlet
of raw mill which maintains the flow of feed. The hot air from preheater are also inlet into
the raw mill to initially heat the raw material to remove moisture content in order to avoid
wear and tear. It has a upthrust bearing at the bottom of table which is taper roller bearing.
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i. CYCLONES
Cyclone is a conical vessel into which a dust-bearing gas-stream is passed tangentially.
The fine particles and hot air enter into the cyclones in which there is effect of
cyclones due to which air and few dust particles enter into the system fan. There is also
the rotary feeder in cyclones which controls the feed. Air is continuously pumped from
down in the cyclones. The particles at the
bottom are further transferred to air sliders. In lucky cement plant 4 cyclones are used
in the VRM area which purify the hot gas which is coming from VRM .
ii. AIR SLIDES
Air Slides is a mean of transportation in the cement plant it take the material from one
place to another with the help of air. Bags and blowers are used in air slides. Air slides
are normally used at the bottom of cyclones
iii. ID FAN
ID fan or induced drafts fans are used to supply hot air from preheater to raw mill. It
also produces negative pressure in kiln.
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iv. SYSTEM FAN
System fan is also an I.D fan but it is used for the suction of air from the Vertical Raw
Mill through the cyclones. It sucks the hot air from the Vertical Raw Mill and send it
to Bag house. It also works for maintaining the negative pressure into the Vertical Raw
Mill.
v. BAG HOUSE
Bag house is a collective name of many bag filters. Bag house has 20chambers and
each chamber contains 114 bags. It is also known as dust collector or fabric filters. In
lucky cement the most common type of bag filters are used which operates with a
velocity of about 0.01 m/s across the bag surface. Bag house fan is a suction fan which
helps the bag house in filtering the hot air from cyclones. If it does not work properly
then there is a need to shutdown the plant because it also helps in producing the
negative pressure and prevention of atmosphere from pollution.
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vi. STORAGE OF GRINDED RAW MATERIAL
Homogenization of grinded raw materials the raw mix is stored in the silo that’s why its
need to homogenize it for this purpose heavy compressor are used which throws air from
the downward due to which a continuous motion occurs in the material and
homogenization of grinded raw material takes place
6. KILN AREA
Before the materials enters the kiln, it goes through a number of stages, like after being
crushed the material consisting of limestone, litharge, clay enters the silo with the help of
pneumatic system, as the material is in the form of powder
Important Stages before the Kiln
Silo before Pre heating tower:
The main function of silo is to store the raw material that is to be fed in the kiln through
pre heating tower.
The material is stored in it if the crusher, VRM or any other component fails we should
have feeding for the kiln so that the production is not affected
There are two types of silo commonly used to store the material.
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i) Blending Silo
ii) CF Silo
Lucky cement used CF silo to store the material, this type of silo mixes and blends the raw
material with the help of air blowers that is installed beneath the silo. There are 8 air slides
in the silo. The material passes from the bin to the shank through motorized valve.
Motorized valve is used to check the feeding while the shank is used to control the feed to
the pre heating tower
Bucket Elevator:
The bucket elevator is an important conveying system for the movement of the material
from the silo to the pre heating tower.
The bucket elevator consists of belts and buckets ranging from 380 to 450. The different
portions of the belts are connected together through fastener joint. The fastener joint
consist of steel plates on both the sides of the belts and connected together by nut and bolt.
On the top of the Pre heating tower we have a motor connected to a gear box that is used
to drive the belt and control its speed.
Pre Heating Tower:
It is used to initially heat the powered material and to prepare it for feeding it in the kiln.
The pre heating tower uses the hot gases produced in the kiln and hood to heat the powder.
The hot gases are passed from hood to the pre heating through a tertiary duct passing
above the kiln. Because of this we utilize the energy of the gases produced in the kiln
instead of wasting them. These hot gases are further used after passing through the pre
heater to the CT fan, coal fan etc.
The kiln consists of four stages, each having feeders to control the material to be fed in the
kiln through valves. The pre heating towers has alternating cyclones and risers. The risers
are used to suck the air so that it can pass through the powder.
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KILN
Simply kiln is type of a large oven used for baking or drying cement.
Cement kilns are used for the pyro processing stage of cement manufacture. The
materials from raw mill after passing from preheaters enter in kiln and are heated up to
1450 °C. The largest kilns today can produce around 10,000 tons per day.
Kiln at Lucky Cement
65meter long
Internal Diameter 4.3m
3.84° slope
Rotation 4-5 rpm
Capacity 3000tonns/day
In kiln calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium
silicates. The capacity of kiln defines the capacity of plant in Lucky Cement CO. Raw mix
is fed in at the upper end, and the rotation of the kiln causes it gradually to move downhill
to the other end of the kiln. At the other end fuel, like oil, gas or coal is burned to produce
a flame. As material moves under the flame, it reaches its peak temperature, before
dropping out of the kiln tube into the cooler.
Fans are also used at different positions to control the temperature of the shell especially
near the burning zone.
Sensors are used throughout the kiln to monitor the temperature around the kiln. Because
of this we can observe bricks removal or fan failure.The brick failure can also be
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observed through naked eyes as the region becomes red hot.
Thrust bearing are used to move the supporting rollers between a limit of 50mm so as to
avoid the steps that can be produced under high stresses betweenroller and the cast iron
tire.
Cooling of clinker
In lucky cement grate type cooler is used having two main advantages i.e. rapid cooling of
clinker that is necessary for quality and these coolers don’t rotate as early ones did so the
air can be ducted out easily and can be used for better combustion. This cooler consists of
a perforated grate through which cold air is blown enclosed in a rectangular chamber a
bed of clinker up to 0.5m deep moves along the grate the grates are moved with the help
of hydraulic system.
At the end of cooler a crusher system is fixed that crushes chunks of clinker into a
prefixed size. Then clinker is discharged from “discharge shoot” on to a pan conveyer.
This clinker transport system transports clinker to clinker storage house.
Hot gases from kiln are not wasted but are used to generate power. These hot gases are
used in waste heat recovery boilers to generate steam and then steam is used to drive
steam turbines to produce electric power.
The Kiln Shell
The shell of the kiln is pasted inside with fire bricks tightly attached to another throughout
the circumference because the inner temperature of the kiln ranges from 400 C to 1400 C.
The material of the shell cannot sustain such high temperatures so we have to use ceramic
bricks as refractory material.
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Tyres and Rollers
The purpose of tyres (often called riding rings) and rollers is to support the kiln and allow
it to rotate with minimal friction. At lucky cement kiln rests on three rollers each station
consists of two rollers. These rollers are supported by a shaft and half journal bearing, the
temperature of these bearings is very important to be kept constant. A push tyre or thrust
roller is also present at these stations which are used to translate the tyre on kiln linearly as
to generate uniform stresses on rollers otherwise because of heavy load of kiln steps are
formed on rollers at such stations.
The Kiln Drive
A motor drives a reducer gear box assembly that is connected to a pinion gear through
flexible coupling (shrimp coupling) to avoid radial and axial torques. The grith gear is
connected with tangent plate because they act like spring and avoid the direct contact of
kiln with gear.
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Rotary kilns run 24 hours a day, and are typically stopped only for a few days once or
twice a year for essential maintenance. One of the main maintenance works on rotary kilns
is tyre and roller surface machining and grinding works which can be done while the kiln
works in full operation at speeds up to 3.5 rpm. This is an important discipline, because
heating up and cooling down are long, wasteful and damaging processes. Uninterrupted
runs as long as 18 months have been achieved.
7. WASTE HEAT RECOVERY
In lucky cement heat waste from the kiln is utilized in heating the boiler. From boiler the
turbine is running making lucky cement’s own power resource. First the waste heat from
kiln is send to boiler which has three section economizer, evaporator and superheated
region.
Boiler is eleven stages boiler. The heat is first added to economizer then to boiler heater
and then to evaporator and again then to heater and again to super heater. From super
heater the steam is transferred to turbine for production of electricity. The boiler is
connected with a deaerator is a device that is widely used for the removal of oxygen and
other dissolved gases from the feed water to steam-generating boilers. In particular,
dissolved oxygen in boiler feed waters will cause serious corrosion damage in steam
systems by attaching to the walls of metal piping and other metallic equipment and
forming oxides. Dissolved carbon dioxide combines with water to form carbonic acid that
causes further corrosion.
In turbine room there is turbine called impulse condensing turbine in which the steam is
input radially and ejected axially. The turbine is supported by bearing and axial thrust
bearing. Theses bearing are white metal bearing which need proper lubrication. There is
system of oil filter and oil cooler in order to save wear and tear in bearings. It has
hydraulic lever which could stop the supply of steam.
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Then the steam after striking with turbine blades condenses and is brought to absorption
chamber where it is mixed with new cooled water and transferred to the cooling towers in
order to condense the water. The water is provided to boiler from RO plant. The
absorption chamber has tubes which condenses the steam.
