• Syed Asim Ali Shah• Internee • 140810• Production

Name

DesignationCode

Department

• M Armaghan Aized ( Deputy General Manager, HR )• 10/06/2015

Submitted to

Date of submission

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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 incement 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).

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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 yard6) 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

1Moisture content of the slurry is 35-50%.

Moisture content of the pellets is 12%.

2Size 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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3The 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.

5The 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.

6The 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.

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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.

MillsBall and tube mills - mills with slide shoe bearings; Vertical ring and roller mills; Roller press and ball mill combinations; Horizontal Roller mill

ClassifiersWet classifiers; Dry c1assifiers- grit separators, mechanical air separators; High efficiency separators

BlendingSlurry blending - slurry mixer; Air merge blending - batch and continuous

PreheatersCalciners 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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KilnsShaft kiln-Rotary Kiln - Wet - Long dry - Short - Semi dry and Dry pre heater kilns

CoolersRotary Cooler - planetary cooler; Traveling and Reciprocating grate coolers; Static grate, pendulum coolers and cross bar coolers

Dust collectorsCyclones; poly and multiclones; Bag filters- glass bag filters;

Gravel Bed filters; Electrostatic PreCipitators

Packing machines

Stationary - rotary - rotary electronic

DespatchesMechanized-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/Dout1/2 – 1/Din

1/2)

If the coming mass of particle is infinite

E= kb / Dout1/2

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 OFVERTICAL 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. hopper2. bine 3. Silo

They are either cylindrical or rectangular vassal. A silo is relatively tall and bin are not so talland 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 baginto 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 systemwill make use of certain pressure and flow of air to clear the surface dust of each bag.

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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 dampers2. Filter bag tensioning system3. Anti-collapse rings on bags4. 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 source3. Compressed air storage header4. Solenoid valve5. Diaphragm valve6. 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 bag3. Movable frame from which bags are hung4. 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 efficiency2. Pressure drop of the line, including a 5 stage preheater, is less than 50 mbar3. Heat and energy consumption is reduced4. Reduction of dust load to filter5. Technical advantages6. Overall design to achieve a very low pressure drop7. High heat exchange efficiency8. Large cone to avoid build-up9. 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.

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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

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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 NAMESCHEMICAL NAME CHEMICAL FORMULA ABBREVIATIONS

ALITE TRI CALCIUM SILICATE 3CAO.SIO2 C3S

BELITEDI CALCIUM SILICATE 2CAO.SIO2 C2S

CELITETRI CALCIUM ALUMINATE 3CAO.AL2O3 C3A

BROWNMILLERITE

TETRA CALCIUM ALUMINO

FERRITE4CAO.AL2O3.FE2O3 C4AF

STRENGTH, HEAT OF HYDRATION AND SETTING CONTRIBUTION

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1. 1st to 7th day C3A > C3S > C4AlF > C2S2. 1st month C3A > C3S > C4AlF = C2S3. 3rd month C3A = C3S = C4AlF < C2S4. 1st year C2S > C3S >C3A = C4AlF5. 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 andalternate rows are carried on a movable frame to which help inreciprocating 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.

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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, stonewarelike 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).

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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 material3. 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 crushing6. 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

INTERNSHIP REPORT (LUCKY CEMENT LIMITED)

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

departmenthelpandguidemea lot.

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