Tata Steel

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

•


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.


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


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


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.


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


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


1.Raw Material Preparation

2.Formation of Green Pellets

3.Induration of Green pellets


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


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


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


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


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


ROKSH Separator






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”


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


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


Green Pellets

Rejected Pellets

Green Pelletising building (inside view)


Green Pelletising Disc (side view)






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


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.


Stage 3: Pellet Hardening at Tata SteelA I d ti PA. Induration Process


Temperature Profile of Indurating Machine


Indurating Furnace Structure (outside view)


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


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


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


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


–Reducibility Index (RI), >65 % –Swelling Index (SI), <18 %

THANK YOU


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