DG Cement Khairpur Internship Report (More Info Added and more explained)

 Internship  Internship Report 2010

Internship Report DG Khan Cement Company, Khairpur Plant Chakwal

Tutmash Shafi Akhtar  SP07-BEC-85

Department Of Chemical Engineering COMSATS Institute Of Information technology, Lahore Tutmash Shafi Akhtar (SP07-BEC-85)  Department Of Chemical Engineering, CIIT Lhr 

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 Internship  Internship Report 2010

::  Table Of Contents :: Serial  No. 1

Area

Page  No

Introduction D.G. Khan Cement Company Ltd

2 3 4 5 6 7 8 9 10

Portland Cement And Clinker  Composition History Of Cement Types Of Cement General Steps involved in Production Quarry and lime stone crusher  Storage yard (Operation of stacker, reclaimer & side scrapper) Raw mill feed area, Raw mill, EP & conditioning tower  Labortories Coal yard, Coal mill feed area, coal mill, storage of coal

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CF Silo, low bin, preheaters cyclones and precalciner 

12 13 14 15 16 17 18 19 20

Kiln and cooler  Cement mill feed area, gypsum crusher  Cement mills Packing plant Setting & Hardening of Cement Uses of Cement Safety Envirnmental Effects Suggestion to the Management

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

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 Internship  Internship Report 2010

Acknowledgement My 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 (Trainee Engineer) Engineer) and Mr.Umar Mr.Umar Rehman (Trainee (Trainee Engineer) 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 capacit capacity y of 14000 14000 tpd(to tpd(tons ns per day).P day).Pres resent ently ly the compan company y is also also export exporting ing the cement 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  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 vertical Mills in Pakistan. Pakistan. The new plant is not only increasing increasing the capacity but also providing providing   pro proxi ximi mity ty to the the untap untappe ped d mark market et of North Northern ern Punj Punjab ab and and NWFP NWFP besi beside dess maki making ng it more 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 World Bank’s Bank’s enviro environme nmental ntal standa standards rds.. It has been been certifi certified ed for “Envi “Environ ronmen mentt Manage Managemen mentt System” ISO 14001 by Quality Assurance Services, Australia. The company was also certified for  ISO-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...

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

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 Internship  Internship Report 2010

Cement : a ceme cement nt is a bind binder, er, a subs substan tance ce that that sets sets and and hard harden enss indepe independe ndentl ntly, y, and can bind bind other other materia materials ls togeth together. er. The word "cement" traces to the Romans, Romans, who used the term opus describ ribee maso masonr nry y resem resembl blin ing g mode modern rn caementicium to desc 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 of  cement in general use around the world because it is a basic ingredient of  concrete, concrete, mortar , stucco and most non-specialty grout. grout. It is a fine powder produced powder produced by grinding Portland cement clinker (more clinker (more than 90%), a limited amount of calcium 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 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 (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, stone, a type of building stone that was quarried on the Isle of Portland in Dorset, Dorset, England. England. Joseph Aspdin, Aspdin , a British bricklayer from 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 " Roman cement" cement" (patented in 1796 by James Parker) and his

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

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 Internship  Internship Report 2010  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, 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, 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), reaction), but concrete made from such mixtures was first used on a large scale by Roman engineers. engineers. They used both natural  pozzolans (trass (trass or  pumice)  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. Caracalla. The vast [3] system of Roman of Roman aqueducts also made extensive use of hydraulic cement. 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 dioxide and chemically combines the primary ingredients into new compounds.

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

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 Internship  Internship Report 2010  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 a nd 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 encountered 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.

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

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 Internship  Internship Report 2010 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 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 lower 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.

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

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 Internship  Internship Report 2010 “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 

Precalc

A completed limestone prehomogenization pile

iner

Typical clinker nodules

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

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 Internship  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 nearby quarry quarry

Unit. Unit. Limesto Limestone ne has the highes highestt composit composition ion in the cement 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 Iron Ore Ore,, Bauxit Bauxites es and silica silica sand: sand: Iron Ore is the only resource that is bought from

contractors. contractors. Iron Ore, Bauxites Bauxites and silica sand are added in small quantities 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: There 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%

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

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 Internship  Internship Report 2010 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 a nd 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 12001300 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   bet betwe ween en them them,, the the lowe lowerr cham chambe berr has has inlet of dust laden air air, from upper  chamber multiple fabric bags with metal struct structure ure inside inside them them hangs hangs into into lower  lower  cham chambe ber, r, in uppe upperr cham chambe berr ther theree 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

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

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 Internship  Internship Report 2010  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 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  dete detects cts the the comp compos osit itio ion n of the the feed feed befo before re it goes goes to the the stor storag agee pile. pile. The The radioactive radioactive material used id “Clifornium”. “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 attr attrac acts ts and and remov removes es meta metall obje object ctss from from the the feed 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)

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2 High grade (pure limestone)

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Iron ore (additive)

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Bauxite (additive)

Stacker : A stacker is a large machine used in bulk in  bulk material handling applications. A stacker's function is to pile bulk material such as limestone, clay, and laterite. It operates on a rail-like structure with movable wheels, stacki stacking ng of materi material al can be perfor performed med in statio stationar nary y or  moveable mode.

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

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 Internship  Internship Report 2010 .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 number of small buckets of low capacity. When this  belt moves, moves, the buckets buckets picks feed from the pile and put it on the belt conveyor. 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 in  bulk material handling. handling. Its function is to recover bulk material from a stockpile, which has been stacked by the stacker. Reclaime claimerr travel travel on a rail betwee between n stockp stockpiles iles in the stocky stockyard ard.. It’s It’s electri electricall cally y  powered by means of a trailing cable. Scrapper Scrapper types reclaimer:I reclaimer:Itt has two ams called called “Harrows” “Harrows” These harrows 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  Internship Report 2010

Raw mill Feed area : The raw mill feed area consists of 4 feed hoppers: 

Mixed feed hopper 



Pure limestone hopper 

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Bauxite hopper 

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Iron ore hopper 

The The capa capacit city y of firs firstt two two hopp hoppers ers is 800 800 tons 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  Internship Report 2010 Sections Of Raw Mill: There are 3 sections of a raw mill. 

Table with 3 rollers

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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.

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

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 Internship  Internship Report 2010 Conditioning tower: The 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

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

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 Internship  Internship Report 2010 electrode and the particles stick with it and clean air is exhausted from the chimney.

Working of the electrostatic precipitator: Based 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 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