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Pelletizing PlantPelletizing PlantAtAtAtAt
Tata SteelTata Steel(6.0mtpa 768m2 ) (6.0mtpa 768m2 )
RANCHI 22nd Jul-2011RANCHI 22 Jul 2011
1Pellet Plant Project
Need of Pellet Plant for Tata Steel
• To increase hot metal output to meet 10 MTPA Crude Steel Production
• To improve blast furnace performancea. Increase in blast furnace productivity
b. Decrease in blast furnace fuel rate
c. Decrease in hot metal quality
d. Decrease in Slag Rate
• Extending the life of iron Ore Reservesg
•
2Pellet Plant Project
What are Pellets ?
Pellets are approximately spherical lumps formed byagglomeration of crushed iron ore fines in presence of
moisture and binder, on subsequent induration ataround 1300°C, which suit the requirements of
downstream processes e g Blast Furnaces & Directdownstream processes e.g. Blast Furnaces & DirectReduction.
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Advantages of Pellets
• Standardization – uniform size range , generally within a range of 6–16 mm
• Purity – 63–68% iron mainly Fe O• Purity – 63–68% iron, mainly Fe²O
³
• High and uniform porosity of 25–30%
• Good bed Permeability–Due to Spherical shape and open pores
• Cost-effectiveness• Virtually no loss of ignition
• Fast reduction and high metallization rates
• Fine particles, not suitable for sinter making, are used
• Strength high and uniform mechanical strength even under thermal• Strength – high and uniform mechanical strength even under thermal stress in reducing atmospheres
• Transportable – low degradation under abrasive conditions
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Pellet Vs. Sinter
Parameters Pellet Sinter
Iron Ore Fines Size 80% < 0.045 mm < 8-10 mm
Coal / Coke Size 80% < 0.045 mm < 3.15 mm
Limestone / Pyroxinite 80% < 0.045 mm < 3.15 mm
Agglomeration Process Induration Sintering
Product Size, mm 6-16 mm 6-40 mmProduct Size, mm 6 16 mm 6 40 mm
Tumbler Index (TI),% >92 65
Reduction Degradation Index (RDI), % < 12 27-30
Reducibility Index (RI) % 65 65Reducibility Index (RI), % 65 65
Swelling Index, % < 18
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Process Stages of Pellet Production
Three process stages are involved to produce pellets from raw materials:1. Raw material preparation2. Formation of green pellets3. Induration of green pellets
S f l ll t d ti ll f ti ffi i dSuccessful pellet production calls for an optimum efficiency and harmony between all above three stages with preceding stage highly influencing the subsequent one.
6Pellet Plant Project
Process Flow of Pellet PlantRecirculation LoadNoamundi Recirculation LoadNoamundi
Iron Ore Fines
Limestone Dryer Ball Mill ROKSH Separator
Process Bag House
Anthracite Coaly
BF Gas Hot Air Generator
Separator House
Dense Phase Conveying SystemGround Ore Concentrate
Mixer
Concentrate Materials
Bentonite Powder
Green Mix Materials
Disc Pelletizer
Roller Screen
Process WaterGreen
PelletsRejected Pellets
Hearth & Side Layer pellets
Water from Drainage system
Spiral Classifier
Single Deck Roller screen
Indurating Machine
Product Screens
Product Pellet
Pellet Fines
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Process & Plant Dedusting ESPs
e et es
Pneumatic conveying of ESP Dust
CO GasCoal Tar
Details of facility, input & Output Requirements
Major Units Facilities1 2 Impact Mills (30 tph)1. 2 Impact Mills (30 tph)2. 2 Dryers (5 m X 35 m)3. 2 Grinding Mills (6 m X 12 m)4. 2 ROKSH Separators
Output
Input• Iron Ore Fines• Limestone • Anthracite Coal 5. 2 Process Bag Houses
6. 2 Mixers (620 tph each)7. 10 Disc Pelletizers (156 tph each)8 Single deck Roller Screen
Output• Product Pellet • Pellet Fines
• Anthracite Coal• Bentonite • CO Gas• BF Gas 8. Single deck Roller Screen
9. Induration Machine10. Induration Machine Hood11. 6 Process Gas Fans
• Coal Tar• Power• Process Water• Grinding media 12. 3 Process ESPs & 1 Plant Dedusting
ESP13. 2 Product Screens
Grinding media
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1.Raw Material Preparation
2.Formation of Green Pellets
3.Induration of Green pellets
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Stage 1: Raw Material PreparationD G i di V W t G i di f I O FiDry Grinding Vs Wet Grinding of Iron Ore Fines
SL No.
Parameters Wet Grinding Dry Grinding
1 Production Cost Grinding Cost Rs 275 325 /ton of IOF Grinding Cost Rs 450 500 /ton of IOF1 Production Cost Grinding Cost Rs. 275-325 /ton of IOF Grinding Cost Rs. 450-500 /ton of IOF due to higher consumption of fuel & electricity
2 Grinding of Additives
Separate grinding facility for additives All raw materials like IOF, Limestone & Coal can be grounded together
3 Grinding media consumption
1-1.2 Kg/t of IOF 0.03-0.05 Kg/t of IOF
4 Filtration Required to bring down moisture to 9 % Thickening & Filtration not required
5 Eletrical energy 16-17 kwh/t of pellet 20-22 kwh/t of pelletConsumption
6 Pollution Hazards
Nil dust hazard Requirement of extensive pollution control measure to counter dust nuisance
7 Capital Cost Lower than dry grinding High7 Capital Cost Lower than dry grinding High
T t St l h f d i di b f hi h l i t t
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Tata Steel has gone for dry grinding process because of high alumina content in iron ore fines. Here, wet grinding will have sluggish filtration rate.
Stage 1: Raw Material Preparation at Tata Steel
A. Raw Materials Receiving Circuit
B Additives (Limestone & Coal) Crushing CircuitB. Additives (Limestone & Coal) Crushing Circuit
C. Drying Circuit
D. Grinding Circuit
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Stage 1: Raw Material Preparation at Tata SteelA Raw Materials Receiving Circuit
Track Hopper # 4(5100 t)
Blended Iron Ore fines from Noamundi
S C
1500 tph
A. Raw Materials Receiving Circuit
Paddle Feeder 1500 tph
Iron Ore Fines
850 m3 each
LS
200 m3
C
200 m3
IOF 140,000 TonsStacker Cum Reclaimer LS400 T
Coal400 T
B Additives (Limestone & Coal) Crushing CircuitB. Additives (Limestone & Coal) Crushing Circuit
Impact MillLS
200 m3
C
200 m3
Limestone
100 m3Limestone
100 m3
Coal
100 m3
Coal
100 m3
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Pendulum Bucket Elevator
Stage 1: Raw Material Preparation at Tata SteelC Drying Circuit (2 Parallel Circuit)C. Drying Circuit (2 Parallel Circuit)
Rotary Dryer 2 CircuitTons/Hr
94512.316.2
1246.8Raw Materials Kg/ton of Pellet
Consumption Rate
Lime StoneIron Ore Fines
Limestone
100 m3
Coal
100 m3
Iron Ore Fines
850 m3 each
Dryer Bag House 1
12.37.2
16.29.5
Lime StoneAnthracite Coal
Burner air dilution fan
To Roksh Seperator1 60 tph (12%)
BF Gas
Vol. Flow 50000 Nm3/hr
Cal Val 850 Kcal/Nm3
Rotary Dryer1Size 5 m dia X 35 m long
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To Grinding Circuit
Slope 4 degree
Speed 2.5 RPM
Residence Time 19.2 minutesBurner primary air fan
Stage 1: Raw Material Preparation at Tata Steel
D G i di Ci it (2 P ll l Ci it)D. Grinding Circuit (2 Parallel Circuit)
Dust from Rotary Dryer bag house
1st Process Bag Filter House
Iron Ore + Additives from Rotary Dryer
System
2nd Process BagFilter House
ROKSH Separator
System
Ground Ore Concentrate
Bins
1500 m3 each
Ball Mill #1
6 m X 11.6 m
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ROKSH Separator
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1.Raw Material Preparation
2.Formation of Green Pellets
3.Induration of Green pellets
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Purpose of green ball formation
“ The purpose of the green ball formation is to obtain pellets of the desired size range ( 9 -16 mm) and having a mechanical strength which enable them to be safely transported from the b lli i t t th i d ti hi ”balling equipment to the induration machine”
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Stage 2: Green Pellet Formation at Tata Steel
A. Mixing Circuit (2 Parallel Circuit)
Ground Ore Concentrate Bins
1500 m3
Bentonite Bins
100 m3
Process water & Slurry from dedusting
scrubber
2nd Mixing CircuitEirich Mixer
Green Mix Materials
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Stage 2: Green Pellet Formation at Tata SteelB Green Pelletizing Circuit (10 Parallel Circuit)B. Green Pelletizing Circuit (10 Parallel Circuit)
Green Mix Materialsfrom both Mixers Plough Scrapers
Green Mix MaterialsMix Material Parallel 9 Mix Material Bins
55 m3
ate aBins
Parallel 9 Disc Pelletizers
Disc Pelletizer
Parallel 9 Disc Pelletizers
Parallel 9 Roller ScreensDisc Diameter – 7.5 meter
Disc Slope angle – 44-53 degree
Roller Screens
Throughput Rate – 154 tph
Rotational Speed – 4.7 to 7 rpm
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Green Pellets
Rejected Pellets
Green Pelletising building (inside view)
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Green Pelletising Disc (side view)
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1.Raw Material Preparation
2.Formation of Green Pellets
3.Induration of Green pellets
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Induration of Green PelletsG ll t h l h i l t th h d f h d i• Green pellets have low mechanical strength – hence need for hardening for further processes
• Method for hardening pellets is Induration in which pellets are heated to 1300 1350°C i t ll d1300-1350°C in controlled manner
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Travelling Grate (TG) Vs Grate Kiln (GK)
SL No.
Items Travelling Grate (TG) Grate Kiln (GK)
1 Heat hardening cycle
Drying, preheating, induration and cooling are done on a single grate
Drying and preheating on a grate, induration in rotary kiln and cooling in annular cooler
2 Grate bars Grate bars subjected to high temperature; side & bed layers necessary
No side or bed layers necessaryBed depth is nearly half
3 Pellet movement
Pellet remains stationary throughout the process Pellets tumble continuously in rotary kiln
4 Burners Large number of burners along the length of induration furnace.
Single burner is used in for the kiln.
5 Fans Several fans operating in series with multiple fan controls.
Less number of fans with single fan control.
6 Number of Passes
Multiplicity of passes Grate generally of two pass design
7 Pellet grades Both BF & DR grades Both BF & DR grades
8 Largest Machine 768 m2 (CVRD) and 744 m2 (Samarco) with LKAB-3, GIIC-Bahrain & Tildon-2 with capacity capacity of 6 MTPA each. of 4 MTPA each.
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Stage 3: Pellet Hardening at Tata SteelA I d ti PA. Induration Process
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Temperature Profile of Indurating Machine
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Indurating Furnace Structure (outside view)
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Stage 3: Pellet Hardening at Tata SteelB Pellet Handling & Despatch Circuit
Screening Building
Induration Machine
B. Pellet Handling & Despatch Circuit
BuildingMachine
Emergency stock Pile 10 KT
Pellet fines storage Bin
100 ton
P ll t t k il
Luffing Stacker
Pellet stock pile70000 Tons
Stacker Cum Reclaimer
IOF stock pile
Intermediate storage Bin
2200 ton each
IOF stock pile140000 Tons
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Blast Furnaces
Major Pollution Control Equipments
Process ESP 1 Process ESP 3 Dedusting ESP (HR 41) (HR61) (HR01)
1 Vendor FLS Airtech FLS Airtech FLS Airtech FLS Airtech2 ESP size (m3) 24*24*24 24*24*24 23*12*24 23*12*243 N f fi ld 6 6 3 3
Process ESP 2 (HR51)
Pellet plant
Sl. No. Description
3 No. of field 6 6 3 34 Waste gas volume (Nm3/Hr) 1140000 918000 840000 3060005 Dust load (mg/Nm3) 1500 1500 1500 150006 Emission Level (mg/Nm3) 30 30 30 307 Inlet Gas temperature (Degree C) 175 210 115 608 Design Temperature Allowable (Degree C) 250 for 24 hours 250 for 24 hours 250 for 24 hours 250 for 24 hours9 Collecting electrode thickness (mm) 1.25 1.25 1.25 1.25
10 Discharge electrode type Fabulax Fabulax Fabulax Fabulax11 Discharge electrode thickness, mm 2.7 2.7 2.7 2.712 Rapper system Tumbling Hammer Tumbling Hammer Tumbling Hammer Tumbling Hammer13 ESP Hopper volume (m3) 80 m3 80 m3 50 m3 50 m314 ESP Controller PIACS PIACS PIACS PIACS15 Chain Conveyer System Redler Redler Redler Redler
D&G System Ball Mill SysytemNumbers 2 2Chambers in Each Bag filter 6(5opr+1standby) 12(10opr +2standby)
BAG HOUSE
Chambers in Each Bag filter 6(5opr 1standby) 12(10opr 2standby)
Dust inlet gm/Nm3 216 1020Dust outlet mg/Nm3 10 10*Gas Volume , m3/hr, each stream 335000 734400Maximum Continous Temperature, Deg C. 250 140St ti P W 91 357
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Static Pressure, mmWg -91 -357Pressure Drop over fabric filter,mmWg 150 250Fabric Filter Wooven Glass Polyester*Collected dust from Ball mill Bag filter pnuematically conveyed to Ground Concentrated Bins
Pelletising Plant Layout
30Pellet Plant Project
Evaluation of Pellets
• Tests for physical propertiesp y p p–Crushing Strength: 250 kg/pellet –Tumble & Abrasion Index
• Tumble Index (TI) >92% for the fraction +6 3 mm• Tumble Index (TI) >92% for the fraction +6.3 mm• Abrasion Index (AI) <5% for the fraction -0.5 mm
–Size Distribution+16 < 3 %• +16 mm < 3 %
• +6 mm to -16 mm >90 %• -6mm < 3 %
• Tests for metallurgical properties–Reduction Degradation Index (RDI), <12 % for -3.15 mm fraction
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–Reducibility Index (RI), >65 % –Swelling Index (SI), <18 %
THANK YOU
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