Description
The report explains on internship report of Dewan Cement.
Internship Report
Internship Report
Hatter plant, texela Pakistan
Internship Report
Table Of Contents
Serial No. 1 2 3 4 5 6 7 8
Area
Introduction & process flow diagram Quarry / Mining Mechanical section(crushers) / Hammer crusher Transportation and stacking & grinding Vibrator conveyor and elevators Coal mill / burning (kiln) Preheater / Cement mill packing plant / quality control / suggestions
Page No 4/7 8 / 10 13 / 17 17 / 20 22 24 / 25 27 / 32 33 /34 / 36
Internship Report
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 Dewan 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. Arshad(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. I am also very thankful of my department especially DR.ANWAAR UL HAQ(lecturer chemical eng dept.) and SIR KHALIQ MAJEED(lecturer chemical eng dept.) who arranged my internship in Dewan cement. And finally deepest and warmest appreciation to the whole team of Dewan Cement Company
Internship Report
Executive Summary
Dewan Cement Company Limited is a strategic business unit of MUSHTAQ Group, which is the largest industrial group in Pakistan. Dewan Cement Co. is market leader with respect to market share with about 9.4% 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 kamilpur village near hatter and has offices in different cities of the Pakistan. Factory site Unit 1and 2 that is situated in very remote area of NWFP especially also in different cities of Pakistan , 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 (hatter). Dewan has several competitive advantages. The cost of production is very low because the raw material used in the production process is available from a distance of 3km. The method of production adopted at DEWAN Is dry one. This method is very cost effective because of its lower cost of fuel consumption and it is very environment friendly It has two plants working both in kamilpur hatter. Presently it has a total Installed capacity of 3200 tpd(tons per day).Presently the company is also exporting the cement to Afghanistan. The team of the Dewan Cement is story of success of Dewan Cement. The whole team is self-motivated and had played a vital role in the success of the company.
Internship Report
Dewan Hattar Cement Limited (DHCL)
DEWAN CEMENT is situated about 21 km from the main city of Texela and is the quality cement unit in Pakistan in all respects. It was installed in 2000 as private Project. It completes under private sector under DEWAN MUSHTAQ group Of Industries in 2001. At start it has only one unit-1 (Romania technology) whose production capacity per day was 1600 tons/day. Now they have another unit -2(Romania technology) whose production capacity per day is 1600 tons, per day. There are two types of cements but this Dewan cement only produces the first one.
i. ii.
OPC “ordinary Portland cement” SRC “sulphate resistance cement”
Dewan hattar Cement Company limited is playing a vital role in constructional and developmental projects in Pakistan by providing a cement of international quality. It is also providing a lot of different jobs thus reducing the ratio of unemployment in this way Dewan group of industries is taking part in the progress and prosperity of the country.
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Cement Manufacturing Process
Quarry
Crusher
Stock Piles
Kiln
Pre-heater
Raw -Mil
Cooler
Clinker
Cement Mil
Packing
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Overall flow diagram
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1 Quarry
It means to excavate the material over the surface. It is located 7 km away from the factory .it has three sections. 1. Mining section. 2. Mechanical section 3. Auto maintenance
There are total 7 leases for the mining of raw material.
Total area which has been leased from GOVT of Pakistan for a specific periods of time.
LIMESTONE
Total leases for limestone: These deposits are sufficient for about: 02 more than 50 years.
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SHALE CLAY
Total leases for shale clay: Deposits sufficient for: 01 More than 50 years.
SLATE
Total leases for slate= Deposits sufficient for = 03 More than 50 years.
SILICA SAND
Total leases for silica sand: Surveyed area deposit sufficient for: 01 More than 50 years
GYPSUM AND LATERITE
Gypsum and laterite are purchased from market according to their desired quantity.
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1.1 MINING SECTION
Mining contain two sub operations a) Drilling b) Blasting
A. DRILLING
? First of all drilling is done by the help of drilling machine and screw type compressors. ? The hole size is 3inch in dia and the depth of this hole depend upon the deference between bed and floor, normally the dept is 18 to 20 m. ? The spacing between holes is 10 to 14ft.
B. BLASTING
I.
Explosive Material
? Ammonium Nitrate is used as an explosive ? It is obtained from various fertilizer industries.
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? The safety wire called WABO CHORD which is used to blast the explosive material makes the connection. ? The material obtained after blasting contains large lumps with small amount of fine and little amount of intermediate particles. ? The material is then transported to the lime stone crusher and with help excavator, loader and dampers. ? Gypsum is extracted and transported to the factory locally on yearly contract basis where it is crushed by gypsum crusher.
CRUSHERS
1. Hammer and grate crusher 2. Impact crusher
HAMMER AND GRATE CRUSHER
There are two primary hammer crushers which are used to crush the raw material upto 25mm. Main hopper is used for limestone conveying and two additive hoppers are used for slate, alumina and clay as well. Material is crushed between hammers and grates by impact force.
Capacity:
300ton/hr
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Limestone hopper capacity: Additive hopper capacity: Feed size: Product size: Number of hammers: Number of shafts: Power required to rotate rotor: Speed:
160ton 60ton 800m 25mm 27 6 631kw 1000rpm
IMPACT CRUSHER
Impact crusher is also used for primary crushing of material upto 25mm. In impact crusher there are two rotors on which bars are attached through shafts. Crushing is done in two steps. Primary crushing is done in first step and further crushing is done in 2nd step. There are 12 bars and material is crushed by impact force. It is used for high capacities. Its apron conveyor is moved by hydraulic oil system. Its wear and tear is less than hammer crusher and maintenance is much easier than hammer crusher.
Crusher Capacity: Limestone hopper capacity: Additive hopper capacity:
700ton/hr 160ton 60ton
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Number of rotors: Number of bars: Weight of bar: Length of bar: Product size: Power of primary motor: Power of secondary motor:
2 12 750kg 600mm 25mm 700kw 900kw
1.2 Mechanical section
It involves crushing equipments, crushers, conveyer belts, rollers 1.3 Types of crushers
Normally crushers are categorized into two 1. Primary crushers 2. Secondary crushers
Primary crushers
It includes a) Hammer and grate crusher b) Impact crushers
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Secondary crushers
a) Hammer crushers 1.4 Mechanism of grinding
When the material is subjected to a sudden impact it will yield a few relatively large particles and a number of fine particles with a few particles of intermediate size. If a blow of energy is increased then the large particles will be rather of smaller size. Whereas fine particles will be appreciably increased but there size will not be much altered. It appears that size of fine particles is closely connected with the internal structure of the material and the size of the larger particles is much more closely connected with the process by which size reduction is affected.
1.5
SIZE WISE CATEGORIZATION OF THE CRUSHER
Coarse
1. Hammer and grate crusher 2. Impact crusher
Intermediate
1. Hammer crusher
Fine
1. Ball mill 2. Roller mill
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In the cement manufacture, the feed size for the kiln falls in the range of the fine particles .so mostly intermediate crushers are installed i.e. crushing rolls and hammer mills. Hammer mills is used both for brittle and fibrous materials. it is more suitable for hard materials that are in the range of rock salt to fluorspar on the Mohr scale .crushing rolls are suitable for relatively abrasive solids.jaw crushers are used mostly for coarse crushing and for low capacity. 1.6 HAMMER CRUSHER OPERATION
HAMMER CRUSHER
There is a storage hopper that has a storage capacity of 160 tons i.e. it can hold material of approximately of 4 dampers. From the storage hopper, the material is transferred to the hammer crusher through apron feeder .apron feeder consists of 75plates that are being moved on the rollers. Apron feeder is supported by the bottom plates because when material drops from the dumper, it suddenly exerts pressure on the apron feeder plates .leach apron feeder is 1800 * 12750 mm long. Apron feeder is moved by two motors of 18.5KW each .at the gate of apron feeder there are chains. Where, rpm of the motor is from 200-1200, which rotates the apron feeder. If the material drops from the apron feeder there is a chain scraper that lifts up the dropped materials and drops it to the mill.
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Materials drop from apron feeder onto the rolls. These rolls are moved by a motor. There are two rolls that move in the same direction. These are driven in the same direction through a chain.
These rolls do not take part in the crushing at all. There function is just to feed the material to the hammer crusher. Fine material may drop in the gap between the crusher rolls. Gaps between the two rolls are approximately 25mm which is adjustable. Rolls drop the material to the hammer crusher. There are the six shafts. In the hammer crusher there are 27 hammers. Hammers are separated by spacers there are 22 spacers.
Spacers give a certain kind of gap for the fine material to flow to the bottom. There are 27 hammers and 22 separators. Hammer crusher is operated by a motor of 631kw. Hammer crusher is a high speed crusher in which impact force is the major source of crushing. It depends primarily on the centrifugal force. Where, rpm of the motor is 1000, When the material it may bounce back chain at the gate from where feed is coming does not allow the material to bounce back. There are fixed plates around the periphery of the cylinder. Some crushing especially of the large particles is done by these fixed plates, as the large particles continue to strike against these plates until it splits up. Sometimes lump size particles may not break up then due to the continuous impact it may damage the couplings of the shaft.
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We can change the capacity of the crusher by two ways, 1. By moving the fixed plate 2. By changing the motor rpm As once the fixed plate is fixed during the operation, it cannot be changed or moved again and again so product capacity can be increased by varying the motor rpm only As hammer crusher produces a large amount of fines so it is necessary that a positive There is a hydraulic system that can move the fixed plate. That also saves the motor when a large size particle comes in the crusher. At the bottom of the crusher there are bars through which material drops. Average product size is 25mm. 1.7 Limestone dust
In spite of limestone rock Dewan cement is also using limestone dust which they are getting from some lime crushing factories. That dust is a waste of these factories.
2 TRANSPOTATION & STACKING
? The material being crushed is then transported to the piles by the help of long belt conveyer ? L.B.C is used for the transportation limestone, clay and alumina. ? Belt is troughed with the help of side roller which increase the capacity of belt and safety. So those materials don’t drop side wise during the transportation. L.B.C is driven by motor
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and for support rollers are used. Slotted weights are hanged to maintain tension in the belt. ? Dust separators are installed turning points to avoid environmental pollution. Dust is sucked by the bags in the filter then air pressure (purging) the material is drop on the belt and ultra fine are passed into the atmosphere. ? Belt scale is used for measuring the weight of material on belt. ? Drift switch is used to check the angle of belt. ? These L.B.C dropped the material to the STACKER which automatically form pile with the help of sensors ? L.B.C capacity is 700TPH ? Speed of L.B.C is 80m/min ? There are two piles of mix (limestone, clay, and slate) and two additives piles of aluminium and laterite. ? Capacity of mix pile is16000tons ? Length of mix pile is100m ? All the operations of L.B.C crushers’ motors are controlled from control room. It can be run at local control. If any problem occurs then it give indication in the form of alarm which is then eliminated automatically or manually.
3 FEEDING
TRANSPOTATION OF RAW MATERIALS TO RAW MILL
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3.1
Re-claimer ? It is used to feed the belt automatically from the pile. ? The Re-claimer is bridge type. Its capacity is 350ton/hr. ? The claimer of Mix pile dropped the mix (limestone, clay and slate) on the belt conveyor. This belt drops the material into the secondary hammer crusher which drops the material into the mix hopper. ? Additives (alumina and leterite) piles are also Re claimed by the claimer to the Additives hoppers after passing through secondary crusher. These are two Hoppers for additive piles. ? Secondary crusher is also Hammer crusher which have a capacity of 200ton/hr and a product size of 10mm. ? Iron ore is also transported from the iron or crusher to the iron ore Hooper.
3.2
Weigh feeder ? These are used to feed the belt from the Hooper in the fixed ratio by weight. These are installed at the bottom of Hooper and are controlled by control room.
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3.3
Ratio of feed for OPC 78.2% 21.2% 1.6-2%
Lime stone: Shale: Iron ore:
Limestone and shale from the weigh feeder drops on the feed belt this drop in the raw mill. Iron ore is mixed with limestone and shale on the belt. 3.4 Metal detector
Metal detector is used to detect and then separate the metal piece. It is installed on stacker belt. So that the metal piece do not reach the raw mill. which can cause extreme damage to raw mall. 3.5 Rotary valve
The material from the rotary valve drop on the feed belt which is then dropped to the raw mill.
4 GRINDING
Raw mill
Capacity: Grinding: Type: Hydraulic Pressure on the bearing: Size of media used in 1st zone: 120TPH impact& attrition Ball mill 5 bars 70mm
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Size of media used in 2nd zone: Length of ball mill: Dia of ball mill: Product size: RPM of ball mill: Power consumption of ball mill:
35mm 13m 3.8m 90 µm 17 1600 KW
The crushed material from the quarry after primary crushing is now available for secondary crushing and grinding. Raw mill is used for size reduction of the raw material. ? Size reduction is done to increase the surface area of the material. ? The surface area of material is directly proportional to the chemical reaction rate greater with the surface area greater will be the reaction rate active sides are increased. ? Size reduction is done to increase the 1. Reaction rate 2. Mixing 3. Covering capacity
4.1
Principle of combination
The principle uses for the combination by the raw mill are 1. Impact 2. Attraction
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4.2
Operation of raw mill
Ball mill is used as raw mill. It is central discharge mill. It consists of shell and inside it there are balls and is consist of two chambers and in between there is separation of diaphragm. Material comes from one side and when balls are fall on the material it is crushed by the action of impact force and fine material pass from the diaphragm and again crushed to ultra fine. This material goes to pre heater section.
5 VIBRATOR CONVEYER & BUCKET ELEVATOR
The material that is dropped from the ball mill dropped in the vibrator conveyer this will drop the material into the bucket elevator this will drop to cyclone then to the raw mill again.
6 BUCKET ELEVATOR
Bucket elevator consists of a number of buckets attached together for material conveying at a certain height.
7 SCREW CONVEYER
Screw conveyor is also used for material transportation. It consists of a screw which rotates and transport the material.
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8 AIR SEPRATOR
Air is separated from dust by passing through air bag filters which hold the dust particles and clean air is discharged from air bag filters.
9 CYCLONES
Cyclones are also used for separation of dust from air. Cyclones are used for temporary storage of the material. Air enter tangentially from the top of the cyclone and heavy particles fall from the center of the cyclone and air make a path and goes out from the rising duct of the cyclone.
10 AIR SLIDES
Air slides are used to transport material from the cyclones, silos, and hoppers. Air slide consist of a canvas fabric which is porous through these pores we introduce air which move the material. ? Air lift gives a pressure of 7 bars (with the help of 7 compressor) this pressure transport the material to the silo.
11 DUST COLLECTORS
During the transportation the points where the material change belt, feeding point or discharge points, there are installed dust collector to avoid air pollution.
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12 E.P (ELECTROSTATIC PRECIPOITATOR)
E.P is used for the separation of dust from air. In E.P there are electric charged metal plates on which dust is attached. Material from the raw mill, ID fans collect by E.P then by heavy vibration this material dropped then by screw conveyer to air slide then by the screw conveyer to air slide then to silo.
13 CONDITIONING TOWER
Conditioning tower is used to lower the temperature of hot gases coming from pre heater section. Temperature is lowered to improve the EP’s efficiency.
14 AIR BLASTING
It is used to separate the material from the impeller of ID fan which is collected due to moisture.
15 LUBRICATION & HYDRAULIC OIL
For lubrication and hydraulic oil panel are installed which are auto control. The utilization of this system is on the ball mill, crusher and kiln.
16 COAL MILL
Coal mill is used to reduce the size of the crushed coal into the powder form. Coal is first crushed by hammer crusher from which a product size of 20mm is obtained. This
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coal is further crushed by roller mill and it is then supplied to kiln and pre calciner in pulverized form by blowers and compressors. Coal mill type: Capacity: Product size: Power consumption: RPM of the motor: Feed size: Roller mill 20ton/hr 90 micro meter 200kw 750 20mm
17 BURNING
17.1 ROTARY KILN Rotary kiln is equipment where finely ground and mined raw material are heated or burned to form cement clinker. Composition of clinker is C4AF, C3A, C2S, and C3S. 17.2 ZONES OF KILN
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a. Calcination zone b. Upper transition zone c. Burning zone
d. Lower transition zone e. Cooling zone
17.3 CONSTUCTION Length: Dia: Slope: Angle: 59.9m 3.8m 3.5% of the length 2.29°
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Fuel used: Inside temp of kiln: Preheater out let temp: Kiln RPM: Kiln feed: Inner lining of Calciner : Inner lining of kiln: Centre lining of kiln: Coal feed: Power consumption:
coal, furnace oil, gas 1200-1450 c° 300 c° 3.2rpm 120 TPH low alumina low alumina bricks magnesia syinel fire bricks 3.95t/h 260 KW
17.4 PREHEATER ? Cyclones act as a Pre-heater, material is heated in each cyclone and drop to the rest of the cyclones. ? The temperature in each cyclone is different is varying from 200-900 c° ? Cyclones do dehydration ? Preheater inlet temperature is 700-900 c° ? Preheater outlet temperature is 300 c° ? 80% of calcination occurs in preheater section ? 60% of coal is fired to pre calciner at feed rate of 6ton/hr
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17.5 CALCINER Cyclone A55 act as a Calciner in which the temp is 866 c°-900 c° following reaction takes place. CaCO3 ______________________CaO +CO2 Limestone is converted to lime and carbon dioxide
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17.6 KILN ? Rotary kiln is the main part of the cement industry. The kiln is divided into three zones. ? It consist of upper transition ,burning zone, lower transition ? 120 TPH is fed into the kiln and it remains in the kiln of about 3540min. ? The upper transition zone is made up of low alumina ? The lower transition zone is made up of magnesia bricks 17.7 BURNING ZONE ? The material is fed to kiln where temp is 1200 c°-1400 c° this temp zone is called burning zone. ? In this zone lime and clay undergoes a chemical reaction yielding Ca silicates, Ca aluminates as a product. 2CaO+SiO2___________________Ca2SiO4 3CaO+SiO2___________________Ca3SiO5 3CaO+Al2O3_________________Ca3Al2O6
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4CaO+Al2O3+Fe2O10_________Ca4Al2Fe2O10 All of these by fusion form grayish black compound called clinker. All these by fusion form grayish black compound called clinker.
TEMP C °
100
REACTION
Evaporation of free water
HEAT EXCHANGE
Endothermic
500 and above
Evaporation of combined water
Endothermic
900 and above
Crystallization of amorphous dehydration product
Exothermic
900 and above
Evolution of CO2 from CaCO3
Endothermic
900-1200
Main reaction b/w lime and clay
Exothermic
1250-1280
Commencement of liquid formation
Endothermic
1280 and above
Further formation of liquid and completion of formation of cement compound
Endothermic
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18 COOLING OF CLINKER
Clinkers from kiln have very high temperature so it is cooled in the grate cooler. Hot gases are removed from the duct in the middle of the cooler. Grate cooler has two sections.ist grate and 2nd grate. Capacity: Number of chambers: Number of chutes: 1700ton/day 6 13
Motor power to move grates: 45KW Number of fans: Power of fans: 6 75KW
19 HAMMER CRUSHER
At the end of the grate cooler there is hammer mill which crushed the large lumps of clinker. The clinker is then transfer to the clinker yard with the help of bucket elevator.
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20 CLINKER YARD
Clinker yard is used to store clinkers. Clinkers from the cooler pass through E.P for dust recovery and then by bucket elevator goes to clinker silo where material is stored. Clinker silo have doors through which clinker can move to clinker yard. If there is any problem in clinker silo then a marginal silo can also be used for the storage of clinkers. Capacity of the clinker yard: 50000 tons
21 CEMENT MILL
Cement mill is used for fine grinding (90µm) and it is end discharge type ballmill. 21.1 Principle of grinding Cement mill employs impact (1st zone) and attrition (2nd zone) for grinding. 21.2 Grinding media Metallic balls are used as a grinding media. Construction of cement mill Material of construction of mill: Length of mill: medium carbon steel 13 m
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Diameter of mill: Capacity of mill: Size of media: RPM of the ball mill: Power of motor: Separation of chambers: RPM of motor: Formula of critical speed: Operation speed formula: 21.3 OPERATION OF CEMENT MILL
3.8 m 70ton/hr 30-40mm 17 1600kw Diaphragm 992 76.6/? (mill dia) 32/? (mill dia)
? Clinker from the clinker yard and gypsum from gypsum crusher are transported to their cyclones by belt conveyers. ? The clinker and gypsum are then fed in a fixed ratio with a help of Weigh feeders. ? Then it is transported to the cement silo with the help of bucket elevator. ? Air is introduce at high pressure at the bottom of silo to avoid the lump formation.
22 PACKING PLANT
? The cement from silo one transferred to the 6 cement cyclones with the help of air lift.
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? There is installed a mechanically vibrated screen (10mm) mesh size to avoid any metal piece or anything else below cyclones. ? The cement is packed into bags having capacity of 50 kg per bags ? Six packing plants ? The packing system is fully computerized and works on the programmable logic control (PLC) system. ? Counting of bags is also automatically as well as manually for security system. ? After packing bags are transferred to vehicles by the help of belt conveyer. ? Power consumption per ton of cement is 2.25KWH
23 QUALITY CONTROLL
Quality control system is fully computerized. Raw material from quarry is analyzed and then upon the basis of these compositions feed rate of raw material is given.Samples from the raw mill air lift clinker and cements in the x-rays machine which gives its result to computer which has a program which calibrates its with the standard samples. The samples are fed in the form of press to the x-rays machine. Then finally ratio of sand cement and water is calculated by breaking the cubes of cement.. i. ii. iii. iv. v. Calorie test Sulphur test Auto clave test X-rays test Compressive strength test = SiO2%/Al2O3+Fe2O3
SM “silica modulus “
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AM “alumina modulus” LSF “lime saturation factor “
= =
Al2O3/Fe2O3
CaO/2.8SiO2%+1.18Al2O3%+0.65Fe2O3% Coal is also analyzed in QC. Coal analysis is based on surface and internal moisture, volatile mater, fixed carbon, ultimate analysis and its calorific value. Proximate analysis of coal Total moisture content: GCV: Ash content: Volatile mater: Hard groove index: Size: 15% 6300kcal/kg 15% 38-42% 40-50% 50mm
24 UTILITIES
i. ii. iii. iv. v. vi. Dams Bridges Construction works Roads Towers Electricity
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25 ENVIROMENTAL PROTECTION POLICY OF THE FACTORY
Following major steps have been taken in this regard ? Implementation on industrial waste management policy. ? Installation of the E.P’s ? Implementation of (ISO-9002) rules and regulation. ? Availability of the final product quality testing techniques. ? Award of ISO-9002 certification. ? Implementation of labor laws and role of CBA for the difficulties of workers at the plant site and in the housing colony.
26 Suggestions to improve the organizational prestige
I personally suggest the following steps in quite humble words for the improvements of the repute and honor of the industry. ? Electricity can be generated by recovering waste heat. ? Improvement of the greenery in the vicinity of the plant site and the housing colony to avoid atmospheric heating which badly affects the working and the living temperament of the employees. ? To abide by the rules and regulations of safety engineering and safety requirement during the operations at the plant. ? Need of a proper uniform of the industry for both the officers and workers. Workers during our visit do not wear safety shoes and helmets even on the kiln site.
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? Vocational training of the workers and the professionals through seminars, dialogues with the experts and open sessions will improve the prestige of the industry a lot.
doc_806422216.docx
The report explains on internship report of Dewan Cement.
Internship Report
Internship Report
Hatter plant, texela Pakistan
Internship Report
Table Of Contents
Serial No. 1 2 3 4 5 6 7 8
Area
Introduction & process flow diagram Quarry / Mining Mechanical section(crushers) / Hammer crusher Transportation and stacking & grinding Vibrator conveyor and elevators Coal mill / burning (kiln) Preheater / Cement mill packing plant / quality control / suggestions
Page No 4/7 8 / 10 13 / 17 17 / 20 22 24 / 25 27 / 32 33 /34 / 36
Internship Report
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 Dewan 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. Arshad(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. I am also very thankful of my department especially DR.ANWAAR UL HAQ(lecturer chemical eng dept.) and SIR KHALIQ MAJEED(lecturer chemical eng dept.) who arranged my internship in Dewan cement. And finally deepest and warmest appreciation to the whole team of Dewan Cement Company
Internship Report
Executive Summary
Dewan Cement Company Limited is a strategic business unit of MUSHTAQ Group, which is the largest industrial group in Pakistan. Dewan Cement Co. is market leader with respect to market share with about 9.4% 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 kamilpur village near hatter and has offices in different cities of the Pakistan. Factory site Unit 1and 2 that is situated in very remote area of NWFP especially also in different cities of Pakistan , 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 (hatter). Dewan has several competitive advantages. The cost of production is very low because the raw material used in the production process is available from a distance of 3km. The method of production adopted at DEWAN Is dry one. This method is very cost effective because of its lower cost of fuel consumption and it is very environment friendly It has two plants working both in kamilpur hatter. Presently it has a total Installed capacity of 3200 tpd(tons per day).Presently the company is also exporting the cement to Afghanistan. The team of the Dewan Cement is story of success of Dewan Cement. The whole team is self-motivated and had played a vital role in the success of the company.
Internship Report
Dewan Hattar Cement Limited (DHCL)
DEWAN CEMENT is situated about 21 km from the main city of Texela and is the quality cement unit in Pakistan in all respects. It was installed in 2000 as private Project. It completes under private sector under DEWAN MUSHTAQ group Of Industries in 2001. At start it has only one unit-1 (Romania technology) whose production capacity per day was 1600 tons/day. Now they have another unit -2(Romania technology) whose production capacity per day is 1600 tons, per day. There are two types of cements but this Dewan cement only produces the first one.
i. ii.
OPC “ordinary Portland cement” SRC “sulphate resistance cement”
Dewan hattar Cement Company limited is playing a vital role in constructional and developmental projects in Pakistan by providing a cement of international quality. It is also providing a lot of different jobs thus reducing the ratio of unemployment in this way Dewan group of industries is taking part in the progress and prosperity of the country.
Internship Report
Cement Manufacturing Process
Quarry
Crusher
Stock Piles
Kiln
Pre-heater
Raw -Mil
Cooler
Clinker
Cement Mil
Packing
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Overall flow diagram
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1 Quarry
It means to excavate the material over the surface. It is located 7 km away from the factory .it has three sections. 1. Mining section. 2. Mechanical section 3. Auto maintenance
There are total 7 leases for the mining of raw material.
Total area which has been leased from GOVT of Pakistan for a specific periods of time.
LIMESTONE
Total leases for limestone: These deposits are sufficient for about: 02 more than 50 years.
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SHALE CLAY
Total leases for shale clay: Deposits sufficient for: 01 More than 50 years.
SLATE
Total leases for slate= Deposits sufficient for = 03 More than 50 years.
SILICA SAND
Total leases for silica sand: Surveyed area deposit sufficient for: 01 More than 50 years
GYPSUM AND LATERITE
Gypsum and laterite are purchased from market according to their desired quantity.
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1.1 MINING SECTION
Mining contain two sub operations a) Drilling b) Blasting
A. DRILLING
? First of all drilling is done by the help of drilling machine and screw type compressors. ? The hole size is 3inch in dia and the depth of this hole depend upon the deference between bed and floor, normally the dept is 18 to 20 m. ? The spacing between holes is 10 to 14ft.
B. BLASTING
I.
Explosive Material
? Ammonium Nitrate is used as an explosive ? It is obtained from various fertilizer industries.
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? The safety wire called WABO CHORD which is used to blast the explosive material makes the connection. ? The material obtained after blasting contains large lumps with small amount of fine and little amount of intermediate particles. ? The material is then transported to the lime stone crusher and with help excavator, loader and dampers. ? Gypsum is extracted and transported to the factory locally on yearly contract basis where it is crushed by gypsum crusher.
CRUSHERS
1. Hammer and grate crusher 2. Impact crusher
HAMMER AND GRATE CRUSHER
There are two primary hammer crushers which are used to crush the raw material upto 25mm. Main hopper is used for limestone conveying and two additive hoppers are used for slate, alumina and clay as well. Material is crushed between hammers and grates by impact force.
Capacity:
300ton/hr
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Limestone hopper capacity: Additive hopper capacity: Feed size: Product size: Number of hammers: Number of shafts: Power required to rotate rotor: Speed:
160ton 60ton 800m 25mm 27 6 631kw 1000rpm
IMPACT CRUSHER
Impact crusher is also used for primary crushing of material upto 25mm. In impact crusher there are two rotors on which bars are attached through shafts. Crushing is done in two steps. Primary crushing is done in first step and further crushing is done in 2nd step. There are 12 bars and material is crushed by impact force. It is used for high capacities. Its apron conveyor is moved by hydraulic oil system. Its wear and tear is less than hammer crusher and maintenance is much easier than hammer crusher.
Crusher Capacity: Limestone hopper capacity: Additive hopper capacity:
700ton/hr 160ton 60ton
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Number of rotors: Number of bars: Weight of bar: Length of bar: Product size: Power of primary motor: Power of secondary motor:
2 12 750kg 600mm 25mm 700kw 900kw
1.2 Mechanical section
It involves crushing equipments, crushers, conveyer belts, rollers 1.3 Types of crushers
Normally crushers are categorized into two 1. Primary crushers 2. Secondary crushers
Primary crushers
It includes a) Hammer and grate crusher b) Impact crushers
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Secondary crushers
a) Hammer crushers 1.4 Mechanism of grinding
When the material is subjected to a sudden impact it will yield a few relatively large particles and a number of fine particles with a few particles of intermediate size. If a blow of energy is increased then the large particles will be rather of smaller size. Whereas fine particles will be appreciably increased but there size will not be much altered. It appears that size of fine particles is closely connected with the internal structure of the material and the size of the larger particles is much more closely connected with the process by which size reduction is affected.
1.5
SIZE WISE CATEGORIZATION OF THE CRUSHER
Coarse
1. Hammer and grate crusher 2. Impact crusher
Intermediate
1. Hammer crusher
Fine
1. Ball mill 2. Roller mill
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In the cement manufacture, the feed size for the kiln falls in the range of the fine particles .so mostly intermediate crushers are installed i.e. crushing rolls and hammer mills. Hammer mills is used both for brittle and fibrous materials. it is more suitable for hard materials that are in the range of rock salt to fluorspar on the Mohr scale .crushing rolls are suitable for relatively abrasive solids.jaw crushers are used mostly for coarse crushing and for low capacity. 1.6 HAMMER CRUSHER OPERATION
HAMMER CRUSHER
There is a storage hopper that has a storage capacity of 160 tons i.e. it can hold material of approximately of 4 dampers. From the storage hopper, the material is transferred to the hammer crusher through apron feeder .apron feeder consists of 75plates that are being moved on the rollers. Apron feeder is supported by the bottom plates because when material drops from the dumper, it suddenly exerts pressure on the apron feeder plates .leach apron feeder is 1800 * 12750 mm long. Apron feeder is moved by two motors of 18.5KW each .at the gate of apron feeder there are chains. Where, rpm of the motor is from 200-1200, which rotates the apron feeder. If the material drops from the apron feeder there is a chain scraper that lifts up the dropped materials and drops it to the mill.
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Materials drop from apron feeder onto the rolls. These rolls are moved by a motor. There are two rolls that move in the same direction. These are driven in the same direction through a chain.
These rolls do not take part in the crushing at all. There function is just to feed the material to the hammer crusher. Fine material may drop in the gap between the crusher rolls. Gaps between the two rolls are approximately 25mm which is adjustable. Rolls drop the material to the hammer crusher. There are the six shafts. In the hammer crusher there are 27 hammers. Hammers are separated by spacers there are 22 spacers.
Spacers give a certain kind of gap for the fine material to flow to the bottom. There are 27 hammers and 22 separators. Hammer crusher is operated by a motor of 631kw. Hammer crusher is a high speed crusher in which impact force is the major source of crushing. It depends primarily on the centrifugal force. Where, rpm of the motor is 1000, When the material it may bounce back chain at the gate from where feed is coming does not allow the material to bounce back. There are fixed plates around the periphery of the cylinder. Some crushing especially of the large particles is done by these fixed plates, as the large particles continue to strike against these plates until it splits up. Sometimes lump size particles may not break up then due to the continuous impact it may damage the couplings of the shaft.
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We can change the capacity of the crusher by two ways, 1. By moving the fixed plate 2. By changing the motor rpm As once the fixed plate is fixed during the operation, it cannot be changed or moved again and again so product capacity can be increased by varying the motor rpm only As hammer crusher produces a large amount of fines so it is necessary that a positive There is a hydraulic system that can move the fixed plate. That also saves the motor when a large size particle comes in the crusher. At the bottom of the crusher there are bars through which material drops. Average product size is 25mm. 1.7 Limestone dust
In spite of limestone rock Dewan cement is also using limestone dust which they are getting from some lime crushing factories. That dust is a waste of these factories.
2 TRANSPOTATION & STACKING
? The material being crushed is then transported to the piles by the help of long belt conveyer ? L.B.C is used for the transportation limestone, clay and alumina. ? Belt is troughed with the help of side roller which increase the capacity of belt and safety. So those materials don’t drop side wise during the transportation. L.B.C is driven by motor
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and for support rollers are used. Slotted weights are hanged to maintain tension in the belt. ? Dust separators are installed turning points to avoid environmental pollution. Dust is sucked by the bags in the filter then air pressure (purging) the material is drop on the belt and ultra fine are passed into the atmosphere. ? Belt scale is used for measuring the weight of material on belt. ? Drift switch is used to check the angle of belt. ? These L.B.C dropped the material to the STACKER which automatically form pile with the help of sensors ? L.B.C capacity is 700TPH ? Speed of L.B.C is 80m/min ? There are two piles of mix (limestone, clay, and slate) and two additives piles of aluminium and laterite. ? Capacity of mix pile is16000tons ? Length of mix pile is100m ? All the operations of L.B.C crushers’ motors are controlled from control room. It can be run at local control. If any problem occurs then it give indication in the form of alarm which is then eliminated automatically or manually.
3 FEEDING
TRANSPOTATION OF RAW MATERIALS TO RAW MILL
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3.1
Re-claimer ? It is used to feed the belt automatically from the pile. ? The Re-claimer is bridge type. Its capacity is 350ton/hr. ? The claimer of Mix pile dropped the mix (limestone, clay and slate) on the belt conveyor. This belt drops the material into the secondary hammer crusher which drops the material into the mix hopper. ? Additives (alumina and leterite) piles are also Re claimed by the claimer to the Additives hoppers after passing through secondary crusher. These are two Hoppers for additive piles. ? Secondary crusher is also Hammer crusher which have a capacity of 200ton/hr and a product size of 10mm. ? Iron ore is also transported from the iron or crusher to the iron ore Hooper.
3.2
Weigh feeder ? These are used to feed the belt from the Hooper in the fixed ratio by weight. These are installed at the bottom of Hooper and are controlled by control room.
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3.3
Ratio of feed for OPC 78.2% 21.2% 1.6-2%
Lime stone: Shale: Iron ore:
Limestone and shale from the weigh feeder drops on the feed belt this drop in the raw mill. Iron ore is mixed with limestone and shale on the belt. 3.4 Metal detector
Metal detector is used to detect and then separate the metal piece. It is installed on stacker belt. So that the metal piece do not reach the raw mill. which can cause extreme damage to raw mall. 3.5 Rotary valve
The material from the rotary valve drop on the feed belt which is then dropped to the raw mill.
4 GRINDING
Raw mill
Capacity: Grinding: Type: Hydraulic Pressure on the bearing: Size of media used in 1st zone: 120TPH impact& attrition Ball mill 5 bars 70mm
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Size of media used in 2nd zone: Length of ball mill: Dia of ball mill: Product size: RPM of ball mill: Power consumption of ball mill:
35mm 13m 3.8m 90 µm 17 1600 KW
The crushed material from the quarry after primary crushing is now available for secondary crushing and grinding. Raw mill is used for size reduction of the raw material. ? Size reduction is done to increase the surface area of the material. ? The surface area of material is directly proportional to the chemical reaction rate greater with the surface area greater will be the reaction rate active sides are increased. ? Size reduction is done to increase the 1. Reaction rate 2. Mixing 3. Covering capacity
4.1
Principle of combination
The principle uses for the combination by the raw mill are 1. Impact 2. Attraction
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4.2
Operation of raw mill
Ball mill is used as raw mill. It is central discharge mill. It consists of shell and inside it there are balls and is consist of two chambers and in between there is separation of diaphragm. Material comes from one side and when balls are fall on the material it is crushed by the action of impact force and fine material pass from the diaphragm and again crushed to ultra fine. This material goes to pre heater section.
5 VIBRATOR CONVEYER & BUCKET ELEVATOR
The material that is dropped from the ball mill dropped in the vibrator conveyer this will drop the material into the bucket elevator this will drop to cyclone then to the raw mill again.
6 BUCKET ELEVATOR
Bucket elevator consists of a number of buckets attached together for material conveying at a certain height.
7 SCREW CONVEYER
Screw conveyor is also used for material transportation. It consists of a screw which rotates and transport the material.
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8 AIR SEPRATOR
Air is separated from dust by passing through air bag filters which hold the dust particles and clean air is discharged from air bag filters.
9 CYCLONES
Cyclones are also used for separation of dust from air. Cyclones are used for temporary storage of the material. Air enter tangentially from the top of the cyclone and heavy particles fall from the center of the cyclone and air make a path and goes out from the rising duct of the cyclone.
10 AIR SLIDES
Air slides are used to transport material from the cyclones, silos, and hoppers. Air slide consist of a canvas fabric which is porous through these pores we introduce air which move the material. ? Air lift gives a pressure of 7 bars (with the help of 7 compressor) this pressure transport the material to the silo.
11 DUST COLLECTORS
During the transportation the points where the material change belt, feeding point or discharge points, there are installed dust collector to avoid air pollution.
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12 E.P (ELECTROSTATIC PRECIPOITATOR)
E.P is used for the separation of dust from air. In E.P there are electric charged metal plates on which dust is attached. Material from the raw mill, ID fans collect by E.P then by heavy vibration this material dropped then by screw conveyer to air slide then by the screw conveyer to air slide then to silo.
13 CONDITIONING TOWER
Conditioning tower is used to lower the temperature of hot gases coming from pre heater section. Temperature is lowered to improve the EP’s efficiency.
14 AIR BLASTING
It is used to separate the material from the impeller of ID fan which is collected due to moisture.
15 LUBRICATION & HYDRAULIC OIL
For lubrication and hydraulic oil panel are installed which are auto control. The utilization of this system is on the ball mill, crusher and kiln.
16 COAL MILL
Coal mill is used to reduce the size of the crushed coal into the powder form. Coal is first crushed by hammer crusher from which a product size of 20mm is obtained. This
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coal is further crushed by roller mill and it is then supplied to kiln and pre calciner in pulverized form by blowers and compressors. Coal mill type: Capacity: Product size: Power consumption: RPM of the motor: Feed size: Roller mill 20ton/hr 90 micro meter 200kw 750 20mm
17 BURNING
17.1 ROTARY KILN Rotary kiln is equipment where finely ground and mined raw material are heated or burned to form cement clinker. Composition of clinker is C4AF, C3A, C2S, and C3S. 17.2 ZONES OF KILN
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a. Calcination zone b. Upper transition zone c. Burning zone
d. Lower transition zone e. Cooling zone
17.3 CONSTUCTION Length: Dia: Slope: Angle: 59.9m 3.8m 3.5% of the length 2.29°
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Fuel used: Inside temp of kiln: Preheater out let temp: Kiln RPM: Kiln feed: Inner lining of Calciner : Inner lining of kiln: Centre lining of kiln: Coal feed: Power consumption:
coal, furnace oil, gas 1200-1450 c° 300 c° 3.2rpm 120 TPH low alumina low alumina bricks magnesia syinel fire bricks 3.95t/h 260 KW
17.4 PREHEATER ? Cyclones act as a Pre-heater, material is heated in each cyclone and drop to the rest of the cyclones. ? The temperature in each cyclone is different is varying from 200-900 c° ? Cyclones do dehydration ? Preheater inlet temperature is 700-900 c° ? Preheater outlet temperature is 300 c° ? 80% of calcination occurs in preheater section ? 60% of coal is fired to pre calciner at feed rate of 6ton/hr
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17.5 CALCINER Cyclone A55 act as a Calciner in which the temp is 866 c°-900 c° following reaction takes place. CaCO3 ______________________CaO +CO2 Limestone is converted to lime and carbon dioxide
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17.6 KILN ? Rotary kiln is the main part of the cement industry. The kiln is divided into three zones. ? It consist of upper transition ,burning zone, lower transition ? 120 TPH is fed into the kiln and it remains in the kiln of about 3540min. ? The upper transition zone is made up of low alumina ? The lower transition zone is made up of magnesia bricks 17.7 BURNING ZONE ? The material is fed to kiln where temp is 1200 c°-1400 c° this temp zone is called burning zone. ? In this zone lime and clay undergoes a chemical reaction yielding Ca silicates, Ca aluminates as a product. 2CaO+SiO2___________________Ca2SiO4 3CaO+SiO2___________________Ca3SiO5 3CaO+Al2O3_________________Ca3Al2O6
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4CaO+Al2O3+Fe2O10_________Ca4Al2Fe2O10 All of these by fusion form grayish black compound called clinker. All these by fusion form grayish black compound called clinker.
TEMP C °
100
REACTION
Evaporation of free water
HEAT EXCHANGE
Endothermic
500 and above
Evaporation of combined water
Endothermic
900 and above
Crystallization of amorphous dehydration product
Exothermic
900 and above
Evolution of CO2 from CaCO3
Endothermic
900-1200
Main reaction b/w lime and clay
Exothermic
1250-1280
Commencement of liquid formation
Endothermic
1280 and above
Further formation of liquid and completion of formation of cement compound
Endothermic
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18 COOLING OF CLINKER
Clinkers from kiln have very high temperature so it is cooled in the grate cooler. Hot gases are removed from the duct in the middle of the cooler. Grate cooler has two sections.ist grate and 2nd grate. Capacity: Number of chambers: Number of chutes: 1700ton/day 6 13
Motor power to move grates: 45KW Number of fans: Power of fans: 6 75KW
19 HAMMER CRUSHER
At the end of the grate cooler there is hammer mill which crushed the large lumps of clinker. The clinker is then transfer to the clinker yard with the help of bucket elevator.
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20 CLINKER YARD
Clinker yard is used to store clinkers. Clinkers from the cooler pass through E.P for dust recovery and then by bucket elevator goes to clinker silo where material is stored. Clinker silo have doors through which clinker can move to clinker yard. If there is any problem in clinker silo then a marginal silo can also be used for the storage of clinkers. Capacity of the clinker yard: 50000 tons
21 CEMENT MILL
Cement mill is used for fine grinding (90µm) and it is end discharge type ballmill. 21.1 Principle of grinding Cement mill employs impact (1st zone) and attrition (2nd zone) for grinding. 21.2 Grinding media Metallic balls are used as a grinding media. Construction of cement mill Material of construction of mill: Length of mill: medium carbon steel 13 m
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Diameter of mill: Capacity of mill: Size of media: RPM of the ball mill: Power of motor: Separation of chambers: RPM of motor: Formula of critical speed: Operation speed formula: 21.3 OPERATION OF CEMENT MILL
3.8 m 70ton/hr 30-40mm 17 1600kw Diaphragm 992 76.6/? (mill dia) 32/? (mill dia)
? Clinker from the clinker yard and gypsum from gypsum crusher are transported to their cyclones by belt conveyers. ? The clinker and gypsum are then fed in a fixed ratio with a help of Weigh feeders. ? Then it is transported to the cement silo with the help of bucket elevator. ? Air is introduce at high pressure at the bottom of silo to avoid the lump formation.
22 PACKING PLANT
? The cement from silo one transferred to the 6 cement cyclones with the help of air lift.
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? There is installed a mechanically vibrated screen (10mm) mesh size to avoid any metal piece or anything else below cyclones. ? The cement is packed into bags having capacity of 50 kg per bags ? Six packing plants ? The packing system is fully computerized and works on the programmable logic control (PLC) system. ? Counting of bags is also automatically as well as manually for security system. ? After packing bags are transferred to vehicles by the help of belt conveyer. ? Power consumption per ton of cement is 2.25KWH
23 QUALITY CONTROLL
Quality control system is fully computerized. Raw material from quarry is analyzed and then upon the basis of these compositions feed rate of raw material is given.Samples from the raw mill air lift clinker and cements in the x-rays machine which gives its result to computer which has a program which calibrates its with the standard samples. The samples are fed in the form of press to the x-rays machine. Then finally ratio of sand cement and water is calculated by breaking the cubes of cement.. i. ii. iii. iv. v. Calorie test Sulphur test Auto clave test X-rays test Compressive strength test = SiO2%/Al2O3+Fe2O3
SM “silica modulus “
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AM “alumina modulus” LSF “lime saturation factor “
= =
Al2O3/Fe2O3
CaO/2.8SiO2%+1.18Al2O3%+0.65Fe2O3% Coal is also analyzed in QC. Coal analysis is based on surface and internal moisture, volatile mater, fixed carbon, ultimate analysis and its calorific value. Proximate analysis of coal Total moisture content: GCV: Ash content: Volatile mater: Hard groove index: Size: 15% 6300kcal/kg 15% 38-42% 40-50% 50mm
24 UTILITIES
i. ii. iii. iv. v. vi. Dams Bridges Construction works Roads Towers Electricity
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25 ENVIROMENTAL PROTECTION POLICY OF THE FACTORY
Following major steps have been taken in this regard ? Implementation on industrial waste management policy. ? Installation of the E.P’s ? Implementation of (ISO-9002) rules and regulation. ? Availability of the final product quality testing techniques. ? Award of ISO-9002 certification. ? Implementation of labor laws and role of CBA for the difficulties of workers at the plant site and in the housing colony.
26 Suggestions to improve the organizational prestige
I personally suggest the following steps in quite humble words for the improvements of the repute and honor of the industry. ? Electricity can be generated by recovering waste heat. ? Improvement of the greenery in the vicinity of the plant site and the housing colony to avoid atmospheric heating which badly affects the working and the living temperament of the employees. ? To abide by the rules and regulations of safety engineering and safety requirement during the operations at the plant. ? Need of a proper uniform of the industry for both the officers and workers. Workers during our visit do not wear safety shoes and helmets even on the kiln site.
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? Vocational training of the workers and the professionals through seminars, dialogues with the experts and open sessions will improve the prestige of the industry a lot.
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