Internship Report 2010

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

Internship ReportDG Khan Cement Company, Khairpur Plant Chakwal

Tutmash Shafi AkhtarSP07-BEC-85

Department Of Chemical EngineeringCOMSATS Institute Of Information technology, Lahore

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Internship Report 2010

:: Table Of Contents ::

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

Serial No.

Area Page No

1 Introduction D.G. Khan Cement

Company Ltd

2 Portland Cement And Clinker Composition

3 History Of Cement

4 Types Of Cement

5 General Steps involved in Production

6 Quarry and lime stone crusher

7 Storage yard (Operation of stacker, reclaimer & side scrapper)

8 Raw mill feed area, Raw mill, EP & conditioning tower

9 Labortories

10 Coal yard, Coal mill feed area, coal mill, storage of coal

11 CF Silo, low bin, preheaters cyclones and precalciner

12 Kiln and cooler

13 Cement mill feed area, gypsum crusher

14 Cement mills

15 Packing plant

16 Setting & Hardening of Cement

17 Uses of Cement

18 Safety

19 Envirnmental Effects

20 Suggestion to the Management

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Internship Report 2010

AcknowledgementMy greatest thanks to Allah Almighty. Allah who bestowed me with the ability and potential to complete this Internship. Before I go into thick of the things, I would like to add a few deepest words for the people who were part of this report in numerous ways… people who gave unending support right from the stage the report was assigned. Particularly I also wish to thank the managerial staff at DG Cement who helped me to gain a lot of information regarding the company and cement industry and also who provide me an opportunity to learn and understand the working of organization as an internee. I am also thankful to Mr. Aleem (Trainee Engineer) and Mr.Umar Rehman (Trainee Engineer) who played a role of polar star for me in the organization and whose experience taught me a lot about the industry and the organization.And finally deepest and warmest appreciation to the whole team of DG Khan Cement Company

Executive Summary

Dera Ghazi Khan Cement Company Limited is a strategic business unit of Nishat Group, which is the largest industrial group in Pakistan. D.G. Khan Cement Co. is market leader with respect to market share with about 11.4% market share. Apart from its competitors; its product is high priced yet it has highest market share because of good quality. Its plant is situated in Dera Ghazi Khan and Khair Pur and head office is situated at Lahore. Factory site Unit 1and 2 that is situated in very remote area of Punjab, yet it proved a blessing for the company. Because it has all three basic raw materials i.e. Lime stone, Shale, and Gypsum at one place. It has three plants working two in D.G. khan and one in Khair Pur. First plant is old one and it is Japanese plant. The other two plants are of F.L.Smiths, Denmark. Presently it has a total Installed capacity of 14000 tpd(tons per day).Presently the company is also exporting the cement to Afghanistan, Iraq, UAE and Russia. The team of the D.G. Cement is story of success of D.G. Cement. The whole team is self-motivated and had played a vital role in the success of the company.

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010

D.G. Khan Cement Company Ltd

Introduction

D.G. Khan Cement Company:

D.G. Khan Cement Company Limited (DGKCC), a unit of Nishat group, is the second largest

cement-manufacturing unit in Pakistan with a production capacity of 13,400 tons clinker per day. It

has a countrywide distribution network and its products are preferred on projects of national repute

both locally and internationally due to the unparallel and consistent quality. It is list on all the Stock

Exchanges of Pakistan.

DGKCC was established under the management control of State Cement Corporation of Pakistan

Limited (SCCP) in 1978. DGKCC started its commercial production in April 1986 with 2000 tons

per day (TPD) clinker based on dry process technology. Plant & Machinery was supplied by UBE

Industries of Japan.

Expansion -Khairpur Project

The Group has also set up a new cement production line of 6,700 TPD clinker near Kalar Kahar,

Distt, Chakwal, the single largest production line in the country. First of its kind in cement industry

of Pakistan, the new plant have two strings of pre-heater towers, the advantage of twin strings lies

in the operational flexibility whereby production may be adjusted according to market conditions.

The project equipped with two vertical cement grinding mills. The cement grinding mills are first

vertical Mills in Pakistan.  The new plant is not only increasing the capacity but also providing

proximity to the untapped market of Northern Punjab and NWFP besides making it more

convenient to export to Afghanistan from northern borders.

Power Generation

For continuous and smooth operations of the plant uninterrupted power supply is very crucial. The

company has its own power generation plant along with WAPDA supply. The installed generation

capacity is 23.84 MW.

Environmental Management

DG Khan Cement Co. Ltd., production processes are environment friendly and comply with the

World Bank’s environmental standards. It has been certified for “Environment Management

System” ISO 14001 by Quality Assurance Services, Australia. The company was also certified for

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010ISO-9002 (Quality Management System) in 1998. By achieving this

landmark, DG Khan Cement became the first and only cement factory in Pakistan

certified for both ISO 9002 & ISO 14001...

Cement :a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives that were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment and cement.

Portland cement :

(often referred to as OPC, from Ordinary Portland Cement) is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate (which controls the set time) and up to 5% minor constituents as allowed by various standards.

Portland cement clinker :

is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates (3CaO.SiO2 and 2CaO.SiO2), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium content (MgO) shall not exceed 5.0% by mass

History:

Portland cement was developed from natural cements made in Britain in the early part of the nineteenth century, and its name is derived from its similarity to Portland stone, a type of building stone that was quarried on the Isle of Portland in Dorset, England. Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010Joseph Aspdin, a British bricklayer from Leeds, in 1824 was granted a patent for a process of making a cement which he called Portland cement. His

cement was an artificial cement similar in properties to the material known as "Roman cement" (patented in 1796 by James Parker) and his process was similar to that patented in 1822 and used since 1811 by James Frost who called his cement "British Cement". The name "Portland cement" is also recorded in a directory published in 1823 being associated with a William Lockwood, Dave Stewart, and possibly others.

Aspdin's son William, in 1843, made an improved version of this cement and he initially called it "Patent Portland cement" although he had no patent. In 1848 William Aspdin further improved his cement and in 1853 he moved to Germany where he was involved in cement making. Many people have claimed to have made the first Portland cement in the modern sense, but it is generally accepted that it was first manufactured by William Aspdin at Northfleet, England in about 1842. The German Government issued a standard on Portland cement in 1878

Early uses:

It is uncertain where it was first discovered that a combination of hydrated non-hydraulic lime and a pozzolan produces a hydraulic mixture (see also: Pozzolanic reaction), but concrete made from such mixtures was first used on a large scale by Roman engineers. They used both natural pozzolans (trass or pumice) and artificial pozzolans (ground brick or pottery) in these concretes. Many excellent examples of structures made from these concretes are still standing, notably the huge monolithic dome of the Pantheon in Rome and the massive Baths of Caracalla. The vast system of Roman aqueducts also made extensive use of hydraulic cement.[3] The use of structural concrete disappeared in medieval Europe, although weak pozzolanic concretes continued to be used as a core fill in stone walls and columns.

Types Of Cement :

Sulphate Resistant Cement:

Sulphate Resistant Cement is used in projects such as dams that are exposed to high amounts of sulfates. It is also used wherever there are constructions that are in direct contact with clay soil, which contains a large amount of sulfate salt, such as foundations and pillars. Sulphate Resistant is a pre-blended, ready-to-use cement base grout containing non-ferrous fluidities and anti-shrinkage compounds blended with siliceous aggregate and Portland cement. A highly sulphate resistant cement, with an extremely low C3A content, is utilized in the manufacture of Sulphate Resistant Grout. This special cement is very resistant to attack from sodium and magnesium sulphates found in ground water.

Hydraulic cement :

Hydraulic cements are materials that set and harden after being combined with water, as a result of chemical reactions with the mixing water, and that, after hardening, retain strength and stability even under water. The key requirement for this strength and stability is that the hydrates formed on immediate reaction with water be essentially insoluble in water. Most construction cements today are hydraulic, and most of these are based on Portland cement, which is made primarily from limestone, certain clay minerals, and gypsum in a high temperature process that drives off carbon

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010dioxide and chemically combines the primary ingredients into new compounds.

Non-Hydraulic cement :

Non-hydraulic cement is cement which cannot harden while in contact with water, as opposed to hydraulic cement which can. Non-hydraulic cements are created using materials such as non-hydraulic lime and gypsum plasters, and oxy chloride, which has liquid properties Non-hydraulic cements include such materials as (non-hydraulic) lime and gypsum plasters, which must be kept dry in order to gain strength, and oxy chloride cements, which have liquid components. Lime mortars, for example, "set" only by drying out, and gain strength only very slowly by absorption of carbon dioxide from the atmosphere to re-form calcium carbonate through carbonization.

Portland cement blends :

These are often available as inter-ground mixtures from cement manufacturers, but similar formulations are often also mixed from the ground components at the concrete mixing plant.

Portland Blast furnace Cement contains up to 70% ground granulated blast furnace slag, with the rest Portland clinker and a little gypsum. All compositions produce high ultimate strength, but as

slag content is increased, early strength is reduced, while sulfate resistance increases and heat evolution diminishes. Used as an economic alternative to Portland sulfate-resisting and low-heat cements.

Portland Flyash Cement contains up to 30% fly ash. The flyash is pozzolanic, so that ultimate strength is maintained. Because flyash addition allows a lower concrete water content, early strength can also be maintained. Where good quality cheap flyash is available, this can be an economic alternative to ordinary Portland cement.

Portland Pozzolan Cement includes fly ash cement, since fly ash is a pozzolan, but also includes cements made from other natural or artificial pozzolans. In countries where volcanic ashes are available (e.g. Italy, Chile, Mexico, the Philippines) these cements are often the most common form in use.

Portland Silica Fume cement. Addition of silica fume can yield exceptionally high strengths, and cements containing 5-20% silica fume are occasionally produced. However, silica fume is more usually added to Portland cement at the concrete mixer.

Masonry Cements are used for preparing bricklaying mortars and stuccos, and must not be used in concrete. They are usually complex proprietary formulations containing Portland clinker and a number of other ingredients that may include limestone, hydrated lime, air entrainers, retarders, waterproofers and coloring agents. They are formulated to yield workable mortars that allow rapid and consistent masonry work. Subtle variations of Masonry cement in the US are Plastic Cements and Stucco Cements. These are designed to produce controlled bond with masonry blocks.

Expansive Cements contain, in addition to Portland clinker, expansive clinkers (usually sulfoaluminate clinkers), and are designed to offset the effects of drying shrinkage that is normally

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010encountered with hydraulic cements. This allows large floor slabs (up to 60 m square) to be prepared without contraction joints.

White blended cements may be made using white clinker and white supplementary materials such as high-purity metakaolin.

Colored cements are used for decorative purposes. In some standards, the addition of pigments to produce "colored Portland cement" is allowed. In other standards (e.g. ASTM), pigments are not

allowed constituents of Portland cement, and colored cements are sold as "blended hydraulic cements".

Very finely ground cements are made from mixtures of cement with sand or with slag or other pozzolan type minerals which are extremely finely ground. Such cements can have the same physical characteristics as normal cement but with 50% less cement particularly due to there increased surface area for the chemical reaction. Even with intensive grinding they can use up to 50% less energy to fabricate than ordinary Portland cements.

Non-Portland hydraulic cements :

Pozzolan-lime cements. Mixtures of ground pozzolan and lime are the cements used by the Romans, and are to be found in Roman structures still standing (e.g. the Pantheon in Rome). They develop strength slowly, but their ultimate strength can be very high. The hydration products that produce strength are essentially the same as those produced by Portland cement.

Slag-lime cements. Ground granulated blast furnace slag is not hydraulic on its own, but is “activated” by addition of alkalis, most economically using lime. They are similar to pozzolan lime cements in their properties. Only granulated slag (i.e. water-quenched, glassy slag) is effective as a cement component.

Supersulfated cements. These contain about 80% ground granulated blast furnace slag, 15% gypsum or anhydrite and a little Portland clinker or lime as an activator. They produce strength by formation of ettringite, with strength growth similar to a slow Portland cement. They exhibit good resistance to aggressive agents, including sulfate.

Calcium aluminate cements are hydraulic cements made primarily from limestone and bauxite. The active ingredients are monocalcium aluminate CaAl2O4 (CA in Cement chemist notation) and Mayenite Ca12Al14O33 (C12A7 in CCN). Strength forms by hydration to calcium aluminate hydrates. They are well-adapted for use in refractory (high-temperature resistant) concretes, e.g. for furnace linings.

Calcium sulfoaluminate cements are made from clinkers that include ye’elimite (Ca4(AlO2)6SO4 or C4A3 in Cement chemist’s notation) as a primary phase. They are used in expansive cements, in ultra-high early strength cements, and in "low-energy" cements. Hydration produces ettringite, and specialized physical properties (such as expansion or rapid reaction) are obtained by adjustment of the availability of calcium and sulfate ions. Their use as a low-energy alternative to Portland cement has been pioneered in China, where several million tonnes per year are produced. Energy requirements are lower because of the lower kiln temperatures required for reaction, and the lower amount of limestone (which must be endothermically decarbonated) in the mix. In addition, the

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010lower limestone content and lower fuel consumption leads to a CO2 emission around half that associated with Portland clinker. However, SO2 emissions are

usually significantly higher.

“Natural” Cements correspond to certain cements of the pre-Portland era, produced by burning argillaceous limestones at moderate temperatures. The level of clay components in the limestone (around 30-35%) is such that large amounts of belite (the low-early strength, high-late strength mineral in Portland cement) are formed without the formation of excessive amounts free lime. As with any natural material, such cements have very variable properties.

Geo polymer cements are made from mixtures of water-soluble alkali metal silicates and aluminosilicate mineral powders such as fly ash and metakaolin.

Steps Involved in Cement Production :

A limestone prehomogenization pile being built by a boom stacker A completed limestone prehomogenization pile

Precalciner Typical clinker nodules

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010

Cement Crushing

Quarry:

Quarry is the place from where raw material in extracted. Drilling and blasting is done to extract

the material.A hole of about 10-15 m is drilled and ammonium nitrate in filled as an explosive in

these holes. When this explosive is ignited the rocks are broken into pieces of different sizes. These

pieces sre then loaded on the dumper trucks and conveyod to the crusher. It is located about 3-4

Km from the plant.

Quarry and raw materials:

The following raw material is required in the production process:

1. Lime stone: This raw material is company owned and is extracted from the

nearby quarry Unit. Limestone has the highest composition in the cement

product. 76% of the cement constitutes of limestone.

2. Clay: Clay is another natural resource. This raw material is also company

owned. 24% of cement composition comprises of clay

3. Iron Ore, Bauxites and silica sand: Iron Ore is the only resource that is bought from

contractors. Iron Ore, Bauxites and silica sand are added in small quantities less then one percent

and it helps to strengthen the cement.

4. Gypsum: Gypsum acts as a retarding agent. It slows down the hardening

process which in turn gives the constructor enough time to use it.

Proportions of different Raw Materials:

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010There are basically three main raw materials that are used for the production

of cement.

In addition to that, a small proportion of other additives such as silica and Bauxites are also added.

1. Limestone 76%

2. Clay 24%

3. Iron ore (less than 1%)

4. Silica sand (less than 1%)

5. Bauxites (less than 1%)

Lime stone and clay are extracted from the same place. Iron ore is bought from a contractor.

Limestone Crusher: (EV 200*300) (Hammer Crusher)

Capacity : 1500 tons/hr

Supplier : FLSmidth

Description:

Raw material such as limestone, clay, marl and shale are dumped into hoppers by dump trucks and entered into a hammer crusher through an apron feeder. Inside hammer crusher there are hammers each having a weight of 100-102 kg. They rotate at a speed of 1200-1300 rpm and is capable of crushing feed of very large sizes. Pivoted hammers are mounted on a horizontal shaft, and crushing takes place by impact between the hammers and breaker plates. Heavy-duty hammer crushers are frequently used in the cement industry.These crushers are of two types, with and without grates the crushers used in use in Pioneer Cement have grates beneath them, this is a semicircular grizzly bar placed just close to the crusher assembly. Material is broken first by impact against hammers and then by rubbing action (attrition) against screen bars. There are number of disks attached to the axle, between them is a gap in which hammers are fitted on multiple shafts running across close to edges of disks. Hammers and bushing pins are placed alternately to allow clearance and avoid extra energy needed to run the hammer crusher

Bag Filter :

It separate dust from air. It consists of a box with 2 chambers, with a separation between them, the lower chamber has inlet of dust laden air, from upper chamber multiple fabric bags with metal structure inside them hangs into lower chamber, in

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010upper chamber there is a purging mechanism. A suction fan suck air from upper chamber, the air enter from lower chamber and after passing through

bags it enter upper chamber and then to suction fan,The air when pass through the bags get filtered the dust stick to the bag, after a particular time purging is done which is reversing the flow of air with the help of high pressure air, this lead to falling down of dust, at bottom of lower chamber. The lower chamber have a hopper type bottom into which a screw conveyor is present which move the settled dust to one corner where a downward opening exist from where it is dropped back to the conveyor line. The purpose of bag filter is to avoid pollution plus recovery of material, leading to efficiency,

Composition analyzer ;

A composition analyzer is installed upon the feed conveyor belt. This analyzer

detects the composition of the feed before it goes to the storage pile. The radioactive

material used id “Clifornium”. Its half life is 2.5 years and its price is 84,00000. This

element emits rays which pass

through the feed and are deflected back to the analyzer, which then checks the

composition. The composition of eacs material is specific.

Magnetic separator :

A magnetic separator is installed on the feed belt. It

attracts and removes metal objects from the feed

which are collected in the bin.

Storage Yard:

The crushed material is stored in the form of piles in the storage yard. There are 6

piles in the storage yard. Mixed piles are used in larger quantity where as high grade

and additive piles are used in small quantity.

2 Mixed piles (limestone & clay)

2 High grade (pure limestone)

Iron ore (additive)

Bauxite (additive)

Stacker :

A stacker is a large machine used in bulk material handling applications. A stacker's function is to pile bulk material such as limestone, clay, and laterite.

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010It operates on a rail-like structure with movable wheels, stacking of material can be performed in stationary or moveable mode.

.A stacker is a device which form conical piles of the crushed material. Feed is

conveyod to the stacker through conveyor belts. This stacker then moves too an fro to

make a pile. The stacker belt is called “Jib” in engineering terms.

Now, for conveying this material from piles to the conveyor follweing equipment sre

used :

Side scrapper

Reclaimer

Side scrapper :

Side scrapper is a device which picks the crushed feed from

the piles through its feed belt called “Hoist”. This belt has a

number of small buckets of low capacity. When this belt

moves, the buckets picks feed from the pile and put it on

the belt conveyor. Side scrapper in used for those piles

which are required in low quantity like bauxite and iron

ore.

Reclaimer :

A re-claimer is a large machine used in bulk material handling. Its function is to recover bulk material from a stockpile, which has been stacked by the stacker. Re-claimer travel on a rail between stockpiles in the stockyard. It’s electrically powered by means of a trailing cable.Scrapper types reclaimer:It has two ams called “Harrows” These harrows are inserted into the pile, when they move sideward, the feed drops down the pile. This feed in then collected by high capacity buckets installed in the bottom of the reclaimer. These buckets pick the feed and put it on the the belt conveyor. It is a large capacity equipment and for those piles which are required in high quantity like Mixed Pile.

Types of Reclaimers :

1)Bridge type:This type of reclaimer lies across the pile and run on the tracks laid on both sides of pile shed. . Bridge type reclaimers blend the stacked product as it is reclaimed. This is used to reclaim chevron piles which are actually made of layers of material

2) Boom type:The rail track is only on one side of the pile and the scrapper move on one side of pile scrapping the material and loading it onto the conveyor belt running on the sides of pile

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010

Raw mill Feed area :

The raw mill feed area consists of 4 feed hoppers:

Mixed feed hopper

Pure limestone hopper

Bauxite hopper

Iron ore hopper

The capacity of first two hoppers is 800 tons

while the other two hoppers have a capacity of

600 tons. The feed from each pile is conveyed to

the hoppers through conveyor belts in relevant hoppers. Each hopper has 4 load cells.

Load Cells : These are sensing devices which tells the load being put on the hopper

by the feed.

From these hoppers, the feed in required proportions is transferred by the belt

conveyor to the Raw Mill. A lot of dust is produced during the conveying of material,

to avoid this problem Bag Filters are installed. A Magentic

separator is also intalled to reomove metal impurities.

Raw Mill:

Capacity: 500 tons/hr

Motor power : 4300 kw

Supplier : FLSmidth

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010Sections Of Raw Mill:

There are 3 sections of a raw mill.

Table with 3 rollers

Bottom scrapper

Separator

Table:

The raw feed from the belt conveyor directly falls on

the rotating table of the raw mill. The table contains 3

crushing rollers. The raw fed is crushed to fine powder

with these rollers. The coarse particles are collected at

the bottom of raw mill and are sent to to the vibrator

from where they are sent to to the raw feed belt

conveyor and again recycled to the ram mill for

recrushing. The vibrator is use to handle the quantity of the material being put on the

belt.

Seperator :

At the top of the raw mill, there is separator section. Hot

gases from the kiln comes from the bottom of the raw mill

and lift very fine particles with it. A suction fan with motor

power of 4500 kw produces suction and sends dusty air into

the cyclones at the top. Here the dusty air rotates and

particles are separated from the air. These particles are

collected at the bottom of the cyclone and sent to the CF

silo with the help of air slides. The air which still contains

dust particles are separated in Conditioning tower and

Electrostatic precipitator.

Bottom separator:

Some fine particles from raw feed fall on the table, these particles are collected by

means of a bottom scrapper and sent to the CF silo.

Conditioning tower:

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010The air from the cyclones still contains the dust particles which must be

separated before the air is exhausted to the atmosphere. Air from the separator is

passed through conditioning tower. In conditioning tower, water is sprinkled through

very fine nozzles. The particles in the air get wet and settle down. These particles are

then conveyed to the CF silo via screw conveyor.

Electrostatic precipitator :

The clean air from the conditioning tower still contains some particles which have to

be removed. These particles are separated from air by passing it through the

Electrostatic precipitator.

In Electrostatic precipitator there are 2 corona wires which are mesh like. These wires

are negatively charged. There is a positively charged electrode in the centre which is

equidistant from

both corona wires. Dusty air passes through these corona wires and the particles get

negatively charged. The negatively charged particles in air are then attracted by the

positively charged

electrode and the particles stick with it and clean air is exhausted from the chimney.

Working of the electrostatic precipitator:Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010Based on the application of electrostatic charge to a particle and then subjecting it to oppositely charged surface, it works on the phenomena of

attraction between opposite charges. the dust laden gases flows through a chamber in which it passes through high voltage electric fields formed by alternate discharged electrodes and plate type collecting electrodes. Subjected to electric field the dust particles get charged and fly to collecting electrodes and get deposited there. The dust is dislodged by hammering and drops down in the collecting hopper.High temperature and moisture effect the resistively of dust making it less favourable for collection. Conditioning tower reduces resistively of dust.It works well at t<130c and 15% moisture. Electrostatic precipitator uses the phenomena of attraction between + - to separate fines from air. The air along with dust is charged at anode and then is subjected to – terminal, the particles being solid stick to the –plates, which are hammered after an interval to separate the dust and it settle down and are conveyed by screw conveyor and air slides to steel silo from where it is directly sent to cement Mill

Cleaning of the electrostatic precipitator:In order to remove particles from the electrode . A “Wrapping” device is used. This

device hits the electrode as a hammer and particles fall down from it. These particles

are collected and conveyod to the CF silo via screw conveyor.

Labortories :

There are different laboratories for the determination of quality and strength of the

cement. Different types of tests are conducted to determine different properties of the

product. Also different types of fuels are tested for their inherent properties: for

example:

Fineness of coal

Humidity level of coal

Calorific value of coal

Composition of feed material and product

Settling time of cement

Residual material

Following are the different labs avalible.

Sample prepration lab:

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010In sample prepration lab, different samples of cement are prepared and tested.

Raw material in put in an equipment called “Swing mill”. A swing mill is a

grinding mill. This grinding mill has a special type of vessel in which material is

ground to very fine powder.

Press mill :

The ground material is put into a circular dye and placed into a press mill. The mill

exerts pressure on it and a rigid dye is produced which a metallic circular outer layer.

The press mill exerts a pressure of 150 KN on the dye to produce a sample.

X-ray analysis :

Now, the sample dye is put into an x-ray analysis machine to determine its

composition. Thesample is place for 2 mins in the machine. The x-ray machine is

controlled by a computer software. This software restricts the machine to determine

upto a limit of 6 to 8 elements. After 2 mins , the percentage of each element in a

particular sample is shown on the computer screen. The x-ray machine is very fast in

producing accurate results.

Chemical testing lab :

Chemical testing of a cement sample is done to determined its composition. It was a

slow and time consuming process, but nowdays x-ray analysis is used due to its speed

and accuracy.

In chemical testing lab inspite of x-ray analysis, samples are also tested by manual

experimentation.

For this purpose a distillation unit with a capacity of 25 litrers is used to get distilled

water for experimentation. If normal tap water is used, it may be hard,it can alter the

sample composition and may produce error full results. Two muffle furnaces at 1200

°C and 1600 C° are used to determine the residual matter, volatile matter and

moisture content.

Physical testing lab :

In physical testing lab, physical tests of different cement samples are done to check

its properties.

Following are the equipment available is physical testing lab:

Weigh balance

Turbula mixer

Tensile strength machine

Water bath and curing tank

Compression testing machine

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010 Motor mixer

Coal yard :

Coal yard is the area where coal is stored which is used for burning purposes. There

are different piles for the storage of local and imported coal. The coal is impoted

from South Arica, and Indonesia. The coal is handled by a loader, the loader picks up

the coal and throws on a sieved net which separates bigger pieces of coal and stones

form it, before it goes to the tunnel.

From the tunnels the coal is placed on the belt conveyor which takes it to the coal

mill feed area. Pet coke which is hard is also used in the coal feed.

Coal mill feed area :

After the impurities are removed from the coal, it is chuted on the belt conveyor .A

bag filter is employed which sucks the coal dust and thus prevents the coal from

being wasted. The coal is then shifted to the coal storage hopprs.

Coal storage hoppers :

There are 3 hoppers for the storage of coal. Two hoppers are for the storage of local

coal and the other is for the imported coal. All the three hoppers have a capacity of

250 tons. The coal required in different proportions are chuted on the belt conveyor

from the hoppers. A bag fiter is employed to remove coal dust.

A magnetic separator is employed to remove metal impurities.

This belt conveys the raw coal to the raw coal mill.

Coal mill: ATOX 25

Specifications of coal mill :

Capacity : 52 ton/hr (coal mix)

26 ton/hr (pet coke)

Supplier : FLSmidth

Motor : 600 KW

Sections of a coal mill :

There are 3 sections of a coal mill similar to the raw mill.

(1) Table (2) Rollers (3) Bottom scrappers

The coal on the belt conveyor falls on the table of the mill where rollers grind it to a

fine powder. A blower of very high power pushes very fine particles towards the two

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010fine storage bins. From the 1st storage bin the coal is sent to the kiln for its use

in the burner and from 2nd storage bin it is sent to to the precalciner for

calcinations.

CF Silo (continuous flow) :

The fine particles from the conditioning tower

and electrostatic precipitator and the powdered

feed from the raw mill are conveyed to the

bucket elevator. The bucket elevator picks this

feed and take it to the top of the CF silo and

then throws it in.

Specifications of a CF silo :

Length = 54 m Dia = 22.4 m

Capacity = 25,500 tons

Air circulations :

After the feed is stored in the silo bin. Now for the movement of feed in the bin, air is

blown from the bottom through different points in CF silo. These points are located at

the base of the CF silo.

Due to air circulations, fine particles are sent to air slides from where they are

transferred to Low bin (Loss of weight bin). The capacity

of low bin is 118 tons. The feed from the low bin is sent

to a bucket elevator which lifts it to the preheator.

Pre-heaters:

The bucket elevator puts the material on the top of of 2nd

cyclone. The hot gases from the kiln flow with very high

velocity in countercurrent direction. The hot gasses lift

the particles from the particles from the top of 2nd cyclone

and put it on the top of the 1sr cyclone. From there the

material falls on the top of the 3rd cyclone and

sends it into the 2nd cyclone. Then the material falls on the

top of 4th cyclone and hot gases take it into the 3rd cyclone.. then the material falls on

the top of the 5th cyclone and hot gases take it into the 4 th cyclone and finally into the

5th cyclone preheater.During this complete cycle, the hot gases foe in the

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010countercurrent direction. Thses cyclones serve the purpose of preheating the

feed material with hot gases of kiln.

There are total 10 cyclone preheaters . 5 are on the right side of the precalciner and 5

on the left of the precalciner. The temperature of feed increases as the feed flows

downwards the preheaters.

Pre-calciner:

The feed from the 5th cyclone preheater falls into the precalciner

which has burner with a supply of coal and furnace oil. Here the

calcinations of feed material takes place due to burning. Exchange

of heat also takes place in the pre-calciner. CO2 is evolved and

exhausted in the atmosphere and the feed is entered into the kiln

riser at high temperature. Some of the feed directly goes to the kiln

without going to the pre-calciner through separate pipes.

Kiln :

The preheated feed from the kin and the preheaters enter into the kiln riser. From the

kiln riser the feed enters into the kiln.

A Rotary kiln is a pyroprocessing device used to raise materials to a high temperature (calcinations) in a continuous process. Materials produced using rotary kilns

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Internship Report 2010 

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 or pulverized coal.

Specifications of the rotary kiln :

The rotary kiln has a length of 66 m and dia of 5.5 m.its inclination is 4 %.

Its rotating spped varies according to the quantity of feed entered. Around the inner

dia of the kiln there is refractory lining to prevent the shell from damage and to

control the environment temperature. Outside the kiln there are induced draft fans

which turn on automatically when the shell temperature increase more then a certain

limit.

Kiln Motors:

There are two kiln bases on which motors are installed which impart rotary motion to

the kiln.

Kiln burner :

On the other end of the kiln , there is huge

burner having a supply of coal, furnace oil

and air. The burner emits a flame which is

prolonged with high pressure air. The

flame burn the material and the product is

formed.

Zones of a rotary kiln :

There are different zones in the rotary kiln

namely :

(1) Alex (2) Victor (3) Magkor.

Alex : In this zone, feed from the precalciner and preheaters enter into the

kiln.

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Internship Report 2010 Victor : It is the main reaction zone where the conversion takes place

by burning.

Magkor : In this section clinker formation takes place of the burned material

Sections of a rotary kiln

The ash due to the burning of coal also goes with the product which causes LSF

(limestone factor) to reduce from the required limit. That’s why the material which

enters the kiln has a higher %age

of limestone because it is balanced with the ash of coal. The hot gases from the kiln

are not wasted but used in different equipment in the plant. The feed is dropped into

the kiln and it travel downwards due to downward inclination and revolution of the

kiln, hot gases resulting from the combustion of fuel ked to the desired reactions in

the kiln. There are different zones

Kiln zones:there are four zone of the kiln.1) Calcinations zone2) Transition zone3) Burning zone4) Cooling zone

1) Calcination zone

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Alex Victor Magkor

Internship Report 2010This is the first zone of the kiln in which feed enters from the pre-heater. Temperature of this zone is about 600-1000co.In this zone, low alumina

bricks are installed. In this zone, decomposition of calcium carbonate and magnesium carbonate occurs which are present in limestone. CaCO3 CaO + CO2 MgcCO3 MgO +CO2

2) Transition zoneAfter calcination, the next zone is the transition zone in which high alumina bricks are used. In this zone material liquifycation starts. It is the peak point of calcination fallowed by clinkerization. Temperature of this zone is about 1200-1300C.

3) Burning zoneAfter transition, burning zone is starts and the liquid enters from the transition zone changes into clinker. Temperature of this zone is about 1350-1450 C. Here megnasite bricks are used for the insulation purpose.

4) Cooling zoneThis zone is located below the burner of the kiln for the cooling of clinker. The temperature in this zone is about 1400-1450c0.A clinker with 25-30% liquid in raw mix is considered an ideal raw meal for kiln lining, fuel saving and rapid C3S formation.

Kiln Reactions:Following are the sequences of chemical reactions which occur in kiln.(I)Decomposition of raw materials up to 1300 oC Up to 500 c dehydration of water occurs.From 600-800co dissociation of CACO3 and MgCO3 occurs.From 800-900co formation of C2S occurs.From 1100-1200 formation of C3A and C4AF occurs.Liquid formation at 1250-1280 C.

(ii) Alite (C3S) formation in the burning zone (1280-1450co).(iii)Cooling of clinker.

Kiln hood:

The hot material form the kiln falls into the kiln hood at the end which has an angular

sieve. When material passes through it it attains the shape of clinker. Now this clinker

is sent to the cooler.

Refractory Lining :

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. The refractory selected depends upon the temperature inside the kiln and the chemical nature of the material being

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Internship Report 2010processed. The refractory life is prolonged by maintaining a coating of the processed material on the refractory surface. . 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

Type and properties of bricks used in rotary kiln:There are many types of bricks but in PCL two type of bricks are used1) High alumina bricks2)Magnetite bricks

1) High alumina bricksThey are high refractory whose refractiveness increases with increase of alumina content, having high mechanical strength at high temperature. They are resistant to spalling. From the kiln feed inlet, high alumina bricks are lined from 2m to 37m. They are being imported from Germany.

2) Magnesite bricksThey are extremely high refractory and high thermal resistance. They are chemical bonded to the kiln surface and are resistant to spalling. From the kiln feed inlet, magnesite bricks are lined from 38m to 63m.

3) Castables:It is an unshaped refractory. It is composed of refractory aggregate with high temperature resistance binder i.e. high alumina, which upon addition of water produces concrete. The binders used are calcium aluminates having about 45% alumina content. Such binders are suitable for making insulation castables. Good refractory concrete with rapid hardening, high strength and abrasion resistance is achieved.

Clinker cooler :

The clinker cooler is used to lower the clinker temperature. There are ID fans which

take fresh air from the atmosphere and send it to the cooler. At the bottom of the

cooler there are reciprocating rails which move with the help of hydraulic motors.

These rails convey the clinker forward to the clinker crusher.

Dust collection :

A suction fan is installed which sucks the product dust from the cooler and send it to

the electrostatic precipitator. In EP dust is removed and clean air is exhausted to the

atmosphere through a chimney. The dust particles are to the deep pan conveyor by a

screw conveyor.

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010Clinker crusher :

When the clinker cools and hardens then it is sent to the clinker crusher installed after

the cooler. Big stones of clinker are crushed to small

pieces. The crushed clinker is dropped on the deep pan

conveyor at the bottom of the conveyor which conveys

it to the clinker storage.

Clinker storage :

The clinker from the deep pan conveyor is stored in the

clinker storage. Its capacity is 110,000 tons. Its length is

60 m and its width is 46 m. There are 3 gates at the

bottom of the clinker storage from where the clinker is

sent to cement mill through belt conveyor. Besides the main clinker storage bin, there

is a temporary clinker storage hopper with a capacity of 1400 tons. If the temporay

hopper is also full then the clinker is removed from the hopper and dumped into

clinker storage yard.

Cement mill feed area :

There are 2 cement mills and 6 hoppers (3 for each mill) in the cement mill feed area.

The 1st hopper contains the clinker which is major constituent of the cement. The

cement contains 95 % clinker which is conveyed through weigh feeder to the main

belt conveyor which takes it to the cement mill.

Gypsum addition :

The crushed gypsum from a separate crusher is conveyed by belt conveyor to the

cement mill. It is mixed in the clinker while crushing. Gypsum is added to about 4 – 5

%. Its purpose is to increase the settling time of the cement.

Mixing of additive :

The additive which is pure limestone is also added in the cement mill. Its added to

about 2 %. Its function is to increase strength of cement.

A bag filter collects dust from the main belt and a magnetic separator remove

metallic impurities from entering into the cement mill.

Metal detector ;

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Internship Report 2010To protect the cement mills from damage, a metal detector is installed which

analyzes the feed and if a metal object is found it opens the dividend gate

automatically and sends the feed containing metal objects to the rejected bin, which is

again recycled to the main belt and magnetic seperatoe

removes it.

Cement Mills :

Cement mills specifications OK 36-4 :

Capacity : 175 ton/hr

Motor power : 3400 kw

Supplier : FLSmidth

The feed which is free from impurities falls on the table of cement

mill which contains three rollers. Each roller has weight of 35 tons

and the clearance between table and rollers is 0.5 mm. These

rollers move hydraulically using nitrogen gas as hydraulic fluid.

The rollers crush the feed to a very fine powder. The air slides conveys the ground product to

the bucket elevator which lifts it to enter into the 1st storage silo.

Storage silos :

Specifications of storage silos :

Capacity : 21,000 tons

Length : 45 m

Dia : 22.4 m

There are 3 cement storage silos in which crushed

cement is stored uptill packing.. To convey the cement

to the other 2 silos air slides are used. From these silos

the cement enters air slides by air circulations through

blowers. Now these air slides take the cement to the

packing plant.

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Internship Report 2010

Air slide: It a rectangular tube with two sections, the partition between them is of a fabric layer, pressurized air is injected in the lower section, in the upper chamber fine powder is dropped, due to pressure difference the air penetrate through the fabric, the position of this slide is sloped downwards, this air entrainment lead to powder movement.

Air lift:This operates by fluidizing the powder and elevates it to desired height, the air from compressors flow through the pipes in which powder is dropped into the pipe thus air act as a carrier.

Packing Plant :

The packing plant comprises of 6 packers and 12

terminals. Each packer has a capacity of 100 tons/hr.

The cement bags are attached manually to the rotating

packer which fills the cement bag. When the bag is

filled upto the required weight , it automatically falls

on the conveyor balt which takes the bags to the roller

conveyor. From these rollers the bags slide to

different channels and finally cement bags are loadsed

on the trucks fro dispatch.

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Internship Report 2010

Setting and hardening of Cement:

Cement sets when mixed with water by way of a complex series of chemical reactions still only partly understood. The different constituents slowly crystallise and the interlocking of their crystals gives to cement its strength. Carbon dioxide is slowly absorbed to convert the portlandite (Ca(OH)2) into insoluble calcium carbonate. After the initial setting, immersion in warm water will speed up setting. In Portland cement, gypsum is added as a compound preventing cement flash setting.

Uses Of Portland Cement :The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Users may be involved in the factory production of pre-cast units,

such as panels, beams, road furniture, or may make cast-in-situ concrete such as building superstructures, roads, dams. These may be supplied with concrete mixed on site, or may be provided with "ready-mixed" concrete made at permanent mixing sites. Portland cement is also used in mortars (with sand and water only) for plasters and screeds, and in grouts (cement/water mixes squeezed into gaps to consolidate foundations, road-beds, etc.).When water is mixed with Portland Cement, the product sets in a few hours and hardens over a period of weeks. These processes can vary widely depending upon the mix used and the conditions of curing of the product, but a typical concrete sets in about 6 hours and develops a compressive strength of 8 MPa in 24 hours. The strength rises to 15 MPa at 3 days, 23 MPa at 1 week, 35 MPa at 4 weeks and 41 MPa at 3 months. In principle, the strength continues to rise slowly as long as water is available for continued hydration, but concrete is usually allowed to dry out after a few weeks and this causes strength growth to stop.

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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Internship Report 2010

Safety:

When traditional Portland cement is mixed with water the dissolution of calcium, sodium and potassium hydroxides produces a highly alkaline solution (pH ~13): gloves, goggles and a filter mask should be used for protection, and hands should be washed after contact as most cement can cause acute ulcerative damage 8-12 hours after contact if skin is not washed promptly.The reaction of cement dust with moisture in the sinuses and lungs can also cause a chemical burn as well as headaches, fatigue, and lung cancer. The development of formulations of cement that include fast-reacting pozzolans such as silica fume as well as some slow-reacting products such as fly ash have allowed for the production of comparatively low-alkalinity cements (pH<11) that are much less toxic and which have become widely commercially available, largely replacing high-pH formulations in much of the United States. Once any cement sets, the hardened mass loses chemical reactivity and can be safely touched without gloves.

Sampling fast set concrete made from Portland cement

Environmental Effects :

Portland cement manufacture can cause environmental impacts at all stages of the process. These include emissions of airborne pollution in the form of dust, gases, noise and vibration when operating machinery and during blasting in quarries, consumption of large quantities of fuel during manufacture, release of CO2 from the raw materials during manufacture, and damage to countryside from quarrying. Equipment to reduce dust emissions during quarrying and manufacture of cement is widely used, and equipment to trap and separate exhaust gases are coming into increased use.

Environmental protection also includes the re-integration of quarries into the countryside after they have been closed down by returning them to nature or re-cultivating them.

An independent research effort of AEA Technology to identify critical issues for the cement industry today concluded the most important environment, health and safety performance issues

facing the cement industry are atmospheric releases (including greenhouse gas emissions, dioxin, NOx, SO2, and particulates), accidents and worker exposure to dust.

The CO2 associated with Portland cement manufacture falls into 3 categories:

CO2 derived from decarbonation of limestone,

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Internship Report 2010 CO2 from kiln fuel combustion,

CO2 produced by vehicles in cement plants and distribution.

Source 1 is fairly constant: minimum around 0.47 kg CO2 per kg of cement, maximum 0.54, typical value around 0.50 worldwide.

Source 2 varies with plant efficiency: efficient precalciner plant 0.24 kg CO2 per kg cement, low-efficiency wet process as high as 0.65, typical modern practices (e.g. UK) averaging around 0.30. Source 3 is almost insignificant at 0.002-0.005.

So typical total CO2 is around 0.80 kg CO2 per kg finished cement. This leaves aside the CO2 associated with electric power consumption, since this varies according to the local generation type and efficiency. Typical electrical energy consumption is of the order of 90-150 kWh per tonne cement, equivalent to 0.09-0.15 kg CO2 per kg finished cement if the electricity is coal-generated.

Overall, with nuclear- or hydroelectric power and efficient manufacturing, CO2

generation can be as little as 0.7 kg per kg cement, but can be as high as twice this amount. The thrust of innovation for the future is to reduce sources 1 and 2 by modification of the chemistry of cement, by the use of wastes, and by adopting more efficient processes. Although cement manufacturing is clearly a very large CO2

emitter, concrete (of which cement makes up about 15%) compares quite favorably with other building systems in this regard

Suggestion to the management

Low safety measures. Waste of energy. Regular inspection and maintainance of plant should be done Proper accommodation and messing should be provided to the internees The internees must be given adequate computing facilities. Transport should provide to internees

Refrences:

Trainee Engr.Mr.Aleem

Trainee Engr.Mr.Umar Rehman

www.dgcement.com.pk

www.cementpk.com

www.logicsphere.com www.springerlink.com

Tutmash Shafi Akhtar (SP07-BEC-85)Department Of Chemical Engineering, CIIT Lhr

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