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INTERNSHIPREPORTPRODUCTION PROCESS

15Maple Leaf Cement Company Ltd Iskanderabad

S.NO. TOPICS PAGE NO.

1 Acknowledgement 1

2 Executive summary 2

3 Introduction & history 3

4 Portland cement 4

5 Type of cements 4

6 Methods of cement manufacturing 5to 10

7 Raw Mill 11

8 working principle 11

9 Clinkerization or Cement grinding and storage 12 to 13

10 High-performance gear unit 14

11Hydraulic stations protected

14

12 Raw Mill Design 15 to 16

13 Mill Layout 17

14 Coal Mill (Line-II) 18

15 working principle 18 to 20

16 Double screw feeder or gear unit 21

18 Rotary air separator 22

17 Coal Mill Design 23

18 Kiln (Line-II) 24

Contents

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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 Mepal Cement Limited. Especially NASIR IQBAL (DGM-Process) WAHAB-UR- REHMAN QURESHI (Senior Manager)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.

Muhammad Talha MajeedB.E. (Chemical Engineering)INPROGRESS

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EXECUTIVE SUMMARY

This report is based on the activities performed during the internship at Mepal Cement Limited. Internship duration was 30 days and it provided practical knowledge of working in professional environment. This learning experience is described in detail in the various sections of this report.

In the first section, there is some detail about the company. The history and present status of the company is explained. The organization structure and the details of its management along with its location are also discussed. I have also discussed the operations, process and machine use in cement manufacturing.

The second section provides information about the activities that I performed during the internship. I worked as an internee mainly in production department.

The third and last section includes the conclusion.

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GENERAL VIEW /History of MLCF

Mepal leaf Cement is the third largest cement factory in Pakistan. It was set up in 1956 as a joint collaboration between the West Pakistan industrial development Corporation and the government of the Canada. Mepal leaf produces 11000 ten cement per day.

• In1992, the capacity of Maple Leaf to produce Ordinary Portland Cement (OPC) was 1000 tons/day.

• In 1997, Line-I was commissioned with the Capacity of 3300 tons/day.

• In 2004, Line-I was upgraded to 4000 tons/day.

• In 2006, White Cement Plant is in operation with Capacity of 500 tons/day.

• In 2007, Line-II came into operation with the Capacity of 7000 tons/day.

• At present total clinker capacity of OPC is 11000 tons/day & Cement Capacity of OPC is 12100 tons/day.

Presently Maple Leaf cement has 9% of the market share of OPC and is a leading brand in Pakistan.

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Portland Cement

Portland cement is made by heating a mixture of limestone and clay, or Other materials of similar bulk composition and sufficient reactivity, Ultimately to a temperature of about 1450°C. Partial fusion occurs, and Nodules of clinker are produced. The clinker is mixed with a few per cent of calcium sulfate and finely ground, to make the cement. The calcium sulfate controls the rate of set and influences the rate of strength development. It is commonly described as gypsum, but this may be partly or wholly replaced by other forms of calcium sulfate. Some specifications allow the addition of other materials at the grinding stage.

Types of cement Ordinary Portland Cement (OPC)

Step for the Manufacture of Cement

Mining Crushing Raw milling and homogenization (uniform quality of raw

materials) Clinkerization Cement grinding and storage Packing

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MiningThe cement manufacturing process starts from the mining of raw materials that are used in cement manufacturing, mainly limestone and clays.

CrushingThe limestone is crushed in the first crusher called a jaw crusher and then fed into the second crusher called an impact crusher with mixing of clays to reduce particle size below 50mm. The discharged raw mix (limestone 70%, clays 30%) is fed onto a belt conveyor and passed across a bulk material analyzer.

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Raw milling and homogenization The raw mix, high grade lim0estone, sand, and iron ore are fed from their bins to raw mills, called air swept mills, for drying and fine grinding. The raw mill contains two chambers, separated by diaphragm, namely a drying chamber and a grinding chamber. The hot gases coming from a preheater (preheater / kiln system) enter the mill and are used in raw mills for drying. Then the drying materials enter the grinding chamber of raw mills for fine grinding. The grinding chamber contains a certain quantity of ball charge in a different sizes ranging from 30mm to 90mm. The hot gas and grinding materials mill outlet feeds to a separator which separates fine and course product. The latter, called reject, is sent to the mill inlet via an air slide for regrinding. The hot gas and fine materials enter a multistage "cyclone" to separate a fine materials and gases. The fine material, called raw meal, is collected from the multi-cyclone and then fed into an air slide for lifting called an Aeropol . The hot gases with very fine materials enter an electrostatic precipitator to separate the fine materials from gases. The very fine materials called preheater dust or electrostatic separator dust is collected from filters and fed into screw conveyors and are then mixed with the fine material in an air slide and transported to an air lift vessel via air slide. In the air lift, the raw meal is lifted to the silo by compressed air to the air slide and then stored and homogenized in a concrete silo. Raw meal extracted from the silo, now called kiln feed, is fed to the top of the preheater via an air lift called the Poldos for pyro-processing.Raw material required for cement industry

LIMESTONE (75-80%) CLAY (15-20%) GYPSUM (5%) IRON

Limestone Crusher (Line-II)Page | 8

Hammer Mill EV 200 x 200 (1 Nos)o Output

1000 tons/hr o Specific consumption of Electrical Energy

Maximum 1.2 kWh/ton

Limestone Storage (Line-II)Storage Capacity (Pile)

o 2 x 35000 tons=70000

Standard Deviation of Output

o Maximum 1% of CaCO3

Clay Storage (Line-II)

• Storage Capacity (Pile)

o 2 x 13,000 tons=26000

Storage Bins (Line-II)

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• Bin Capacity (3 Nos)

1 x Iron Ore 625 tons

1 x Clay 195 tons

1 x Limestone 500 tons

( limestone,clay,iron)

Pile CompletionPage | 10

Crusher

o Working hours (Limestone & Clay) 10 Hours a day

o Capacity of Crusher

Lime stone = 1000 t/hr * 10 hr = 10000 Tons

Clay = 400 t/hr * 10 hr = 4000 Tons

o Time taken to complete 1 pile

Lime stone = 30000 tons/10000 tons = 3 days

Clay = 11000 tons/4000 tons = 3 days(Approx.)

Clay Limestone Iron

Clinkerization

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Cement clinker is made by preprocessing of kiln feed into the preheater-kiln system. The preheater-kiln system consists of a multi-stage cyclone preheater with five stages, combustion chamber, riser duct, rotary kiln, and grate cooler. In the preheater, the kiln feed is preheated by hot gas coming from the combustion chamber and rotary kiln. Then the preheated kiln feed is partially calcined (made powdery) in a combustion chamber and riser duct and then completely calcined in a rotary kiln as well as heated to approximately 1400 C to form clinker components. The main source of heat is natural gas. The fuel is used to provide the heat required to convert the kiln feed into clinker. Hot clinker discharge from the kiln drops onto the grate cooler for cooling from approximately 1350-1450 C. In the cooler, the quantity of cooling air required for clinker cooling is extracted from the atmosphere by different cooling fans and fed into the cooler chambers and pressurized through the cooler plate and clinker bed. The cooled clinker discharges from the cooler into the pan conveyor and it is transported to the clinker storage. The clinker is taken from the clinker storage to cement ball mill hoppers for cement grinding. Part of the hot air extracted from the cooler is utilized as a secondary and tertiary air for combustion in rotary kiln and combustion chamber, respectively.

Why does the manufacture of cement produce CO2?

Cement manufacturing is the source of 5% of global CO2 emissions. The cement industry is a natural producer of CO2.

60% of emissions are due to the transformation of raw materials at high temperatures (the "carbonation" of limestone)

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40% result from the combustion required to heat the cement kilns to 1500°C

Cement grinding and storageClinker and gypsum for OPC, limestone for limestone cement, and slag for slag cement are all extracted from their respective hoppers and fed to the cement mills. The ball mill grinds the feed to a fine powder in two chambers, namely the first and second chambers. The two chambers have a certain quantity of ball charge of different sizes from 17mm to 90 mm. The mill discharge is fed to a bucket elevator which takes the material to a separator which separates fine and coarse product. The latter is sent to the mill inlet for regrinding and the final product is stored in concrete silos.   

(Storage silo) (grinding)

PackingCement extracted from silos is conveyed to the automatic electronic packers where it is packed in 50 kg bags and dispatched in trucks.

Raw Mill (Line-II)

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Working principleThe ATOX raw mill uses pressure and shear generated between the rollersand the rotating table to crush and grind raw materials. Feed material is directed onto the grinding table by the feed chute. The rotation of the grinding table

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accelerates the material towards the grinding track and passes it under the rollers. Partially ground material passes over the dam ring encircling the grinding table and into the hot gas stream coming from the nozzle ring.

Mill: Atox 52.5 Motor: 4300 kW Separator RAR-LVT 52.5 Motor: 232 kW Output

o Minimum 540 tons/hr

Specific Consumption of Electrical Energy 18.3 kWh/ton of Raw Meal

( The three cylindrical rollers are rigidly connected to a common centerpieceThis highly efficient separator results in the following benefits:

Lowest specific power consumption for the mill motor Highest mill capacity High grinding bed thickness and low vibrations

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The required fineness of the raw meal is obtained by adjusting the rotor speed.

(Seperator top view)

High-performance gear unitThe axial thrust bearing supporting the grinding table and the grinding force is a reliable hydrodynamic/semi-hydrostatic bearing of segmented design. All the thrust pads are immersed in an oil bath. The lubricant for the thrust pads and for the internal gearings/bearings is conditioned and filtered in a separate pump station.

(Gear unit)

Hydraulic stations protectedFor all ATOX mill installations the hydraulic and lubrication stations are located in indoor facility. The benefit is that operation and maintenance takes place in clean and tempered conditions and that trouble free and long life can be obtained. Apart from the lubrication station for mill gear and grinding rollers also the hydraulic station for the tensioning system as well as pump station for the water injection is located in the hydraulic room.

Raw Mill Design

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1.Mill motor 2.Gear box

3. Grinding table 4. Split scrapers for external circulation

5. Hydraulic cylinder with accumulators 6. Reject sluice

7. Rotary split sluice in heated or non-heated version

8. Reject cone

9. Mill house with lining 10. Nozzle ring

11. Air guide cone 12. Segmented grinding roller

13. Roller hub and wear cover 14. Joint head

15. Torque rod 16. Reject cone

17. Mill and separator outlet 18. Tension rod

19. Hydraulic cylinder with accumulators

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Mill LayoutAs a one-source supplier of complete plants, FLSmidth supplies the ATOX raw mill as well as all other equipment needed for the raw mill department. Mill layout is based on a standardized concept and modules that ensure the most cost-effective raw mill installation. Because gas enters the ATOX mill from one side, the ducting arrangement is as small as possible, resulting in a very compact layout. The dimensioning and selection of cyclones, mill fan and connecting ducting are optimized for low energy consumption.The number of cyclones will be 2, 4 or 6, increasing with the mill size. The raw material feeding and recirculation system is preferably placed at the left side of the ATOX mill, seen from the mill motor. Lubrication stations for main gear, hydraulics and roller lubrication are placed with the pump station inside the structure, below the cyclones. The layout is furthermore prepared for easy access to machinery and components needing overhaul or replacement.

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Coal Mill (Line-II)

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Working principlesThe raw coal enters the mill via a feed screw and is discharged onto the center of the rotating grinding table. The rotation of the table accelerates the flow of material towards the grinding track, where the coal is ground between the table and the three rollers. The coal then continues over the dam ring and is entrained in the hot drying gas that enters the mill house through the nozzle ring. The gas lifts the coarser particles back onto the grinding table and sweeps the finer particles up to the separator. The separator lets the final product proceed to the mill outlet while returning the coarse fraction to the table for further grinding. Having left the mill at the top, the final product continues with the gas to a cyclone or a bag filter, where it is collected.

Mill: Atox 25 Motor: 600 kW Separator RAKM 27.5 Motor: 83 kW Output

o Minimum 52 Tons/hr of Electrical Energy Max 26.5 kWh/ton of Coal Meal

Non-inert operationWhen grinding low-explosive to moderately explosive coal types, the system may operate under non-inert conditions. Non-inert operation allows using excess air from the clinker cooler or from the heat generator for drying and conveying. Neither recirculation of air nor water injection for the purpose of inertisation in the mill is required. This is because atmospheric air can be used to any extent to maintain the necessary flow for drying, transportation and separation without risk of explosion.

Inert operationA common safety precaution is to operate the coal grinding system under inert conditions. This can be achieved at a cement plant by using exit gases from the kiln preheater to dry and convey the material through the mill. A variable amount of cleaned gas can be recycled from the grinding system filter to maintain the required flow for separation and conveying through the mill, independent of theamount of hot gas needed for drying.

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Grinding segmentsBoth the grinding table and rollers are fitted with segmented wear parts. Segmentation allows the use of very hard and wear-resistant material without running the risk of thermal cracks occurring in the wear segments. The cylindrical shape of the rollers makes it possible to reverse the segments, enabling a high degree of material utilisation even in the case of uneven wear. Using wear-resistant, high-chromium white cast iron, high-chromium white caste iron with ceramic inserts or hardfacing ensures long life of the grinding segments.

Effective lubricationAn oil circulation system effectively lubricates the bearings of the grinding rollers. Each roller is fed individually with conditioned oil from a common supply station in which a separate circulation system provides filtration and temperature conditioning. High-temperature grease is used to lubricate the bearings of the smallest mill sizes.

The simple, lightweight loading arrangement ensures the lowest possible inertial reactions to gear and foundation parts. & Mill drive and grinding parts.

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Double screw feederThe raw coal enters the mill from the raw coal hopper and enclosed extraction equipment used a double feed screw. The double screw design and the selection of stainless steel for the screw flights and shafts make the feeder capable of handling wet and sticky material.

(Double screw feeder)

High-performance gear unitThe standard main gear unit for an ATOX mill is the sturdy bevel-helical or more compact bevel-planetary type gear from FLSmidth MAAG Gear. The gears are designed for high dynamic loads with a generous service factor. The axial thrust bearing supporting the grinding table and the grinding force is of a segmented design in which all thrust pads are immersed in an oil bath. The lubricant for the thrust pads and for the internal gearings/bearings is conditioned and filtered in a separate pump station.

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Rotary air separatorThe rotary air separator is flanged to the top of the mill housing. The rotor shaft is driven by a variable-speed AC motor via a gear unit. The rotor runs inside a ring of guide vanes. The material entrained in the air from the mill enters the rotor through the guide vanes. The rotor rejects the coarse particles to be collected by the guide vanes and returned via the reject cone to the grinding table for further grinding, while the air and the finished material leave the separator via the outlet duct. The fineness of the ground product can be adjusted by varying the speed of the rotor.

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Coal Mill Design

1.Main gear unit 2.Hydraulic cylinder, incl. accumulators

3.Tension rod 4.Grinding table with scrapes5.Torque rod connection 6.Grinding roller assembly7.Oil and air connection 8.Water injection9.Double feed screw 10.Reject bin11.Reject cone with return pipe 12.Separator outlet13.Reject cone with return pipe ……..……. …….

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Kiln (Line-II)Cement kilns are used for the preprocessing stage of manufacture of Portland and other types of hydraulic cement, in which calcium reacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of cement are made per year, and cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant.

A typical process of manufacture consists of three stages:

grinding a mixture of limestone and clay or shale to make a fine "rawmix". heating the rawmix to sintering temperature (up to 1450 °C) in a cement kiln; grinding the resulting clinker to make cement.

Output o 7000 tons/Day

Specific Consumption of Heat Energyo Maximum 805 kCal/kg of clinker

Specific Consumption of Electrical Energyo Maximum 28.5 kWh/ton of clinker

• Capacity: 40,000 tons• Time Margin of OK Mills w.r.t. Clinker Dome-II

Capacity of Dome/Clinker Demand in OK Mills = 40,000 tons = 5 days (approx)

Personal CommentsPage | 26

1. Maple leaf is a very good and third largest company of Pakistan.

2. Employees are well mannered and their behavior is ideal.

3. The control system of company is excellent.4. The Senior manager is very good and he guided me

very well.5. I must have to mention the excellent condition of

cleanliness in this company.6. I wish I could join this company after the

completion of my engineering.7. Overall this company is remarkably good but

transport system needs some improvements and can be made better.

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