Steel Making and the Next Steps

WELCOME TO

Steel Making and the next steps

G. Venkateswara Rao

Sr. Manager (MP)

Bailadila Iron Ore Mine,

Kirandul complex

NMDC Limited

What is steel ?---Alloy of Iron, Carbon, manganese, Chromium,

Vanadium, Nickel , tungsten and other elements

Importance of Steel: High

Hardness

Ductility

Malleability

Toughness

Tensile strength

Cast ability

Low cost

Good Corrosion resistance

Reasons for wide range of applications of steel

Wide range of Alloy Compositions

Good Mechanical Properties

Variety of Product forms available

Possibility of changing Mechanical

Properties (Heat treatment)

Small or large,

High-tech or low-tech,

Everyday or specialist.

Steel Applications Home Domestic appliances such as fridges,

washing machines, ovens and microwaves, sinks, radiators, cutlery, hi-fi equipment, razors, pins.

Packaging Food and beverage cans, promotional materials, aerosols, paint and chemical containers, bottle tops and caps

Travel and Transport Car bodies, engine components, wheels, axles, trucks, transmissions, trains, rails, ships, anchor chains, aircraft undercarriages, jet engines components.

Construction Low and high rise buildings, housing, modular buildings, retail, industrial, education and hospital buildings, sports stadia, stations, reinforcing bars for concrete, bridge deck plates, piers and suspension cables, harbours, cladding and roofing, office, tunnels, security, coastal and flood defences.

Power and energy

Oil and gas wells and platforms, pipelines, electricity power turbine components, electricity pylons, wind turbines.

Electrical and Magnetic

Electromagnets, transformer cores, electromagnetic shields.

Yellow goods Earth-moving and quarrying equipment, cranes, fork-lift trucks.

Agriculture and Industry

Farm vehicles and machinery, storage tanks, tools, structures, walkways, protective equipment.

Steel Applications

In short, nothing is manufactured, processed or transported without steel.

Rank Country/Region 2007 2008 2009*

— World 1,351.3 1326.5 1344.7

1 People's Republic of China

494.9 500.5 567.80

— European Union 209.7 198.0 ----

2 Japan 120.2 118.7 87.50

3 United States 98.1 91.4 58.10

4 Russia 72.4 68.5 59.90

5 India 53.1 55.2 56.0

6 South Korea 51.5 53.6 48.60

7 Germany 48.6 45.8 32.7

8 Ukraine 42.8 37.1 29.80

9 Brazil 33.8 33.7 26.50

10 Italy 31.6 30.6 25.30

Top ten steel producing countriesMillion Metric Tonnes

* Up to 2009 December

Top 10 Steel Producing Companies (2008)

Company 2007-08 Rank 2009-10 Rank

Arcellar Mittal 103.30 1st 117.80 1st

Nippon Steel 37.50 2nd 39.60 2nd

BaoSteel Group 35.40 3rd 34.70 3rd

POSCO 34.70 4th 33.90 4th

Hebei Steel 33.30 5th 32.20 5th

JFE 33.00 6th 32.80 6th

Wuhan Steel Group 27.70 7th 28.90 7th

Tata Steel Group 24.40 8th 25.10 8th

Jiangsu Shagang Group

23.30 9th 24.30 9th

US Steel 23.20 10th 21.80 10th

Categories/ Types of Steel Products

Steel Production - Consumption

Top five steel Consuming countriesTop five steel Producing countries

India’s Steel ProductionPRODUCTION OF FINISHED CARBON STEEL (In million tonnes)

YearMain

ProducersSecondaryProducers

GrandTotal

% of share ofSecondary Producers

1991-1992 7.96 6.37 14.33 14.5%

1992-1993 8.41 6.79 15.20 44.7%

1994-1995 9.57 8.25 17.82 46.3%

1996-1997 10.54 12.18 22.72 53.6 %

1997-1998 10.44 12.93 23.37 55.32 %

1998-1999 9.86 13.24 23.82 57.32 %

2000-2001 12.51 17.19 29.7 57.88 %

2001-2002 13.05 17.58 30.63 57.40 %

2003-2004 15.19 21.00 36.19 58.03 %

2004-2005 15.61 24.44 40.05 61.02 %

2006-2007 17.390 37.756 55.146 68.46 %

2008-2009 17.216 46.229 63.445 72.86%

2009-2010 17.900 46.565 65.465 72.66 %

Various types of Iron and Steels:Pig Iron

Cast Iron

Ductile Iron

Wrought Iron

Sponge Iron etc.

Low carbon steel

Medium carbon steel

Plain carbon steels

Alloy steels

Tool steels

Special steels

National steel Policy - 2005

Per capita steel Consumption:

India -- 30Kg

Rural --- 2Kg to be increased to 4Kg by 2019-20

Urbane --- 77Kg to be increased to165Kg by 2019-20

World --- 150Kg

Developed world --- 350Kg

Steel production of India (Year wise)Source: Survey of Indian Industry2010

1 2.4 4.6 6.813.5

30.5 32.340.7 43.5 46.6

52.556.157.1658.9

Production of finished steel in India

Steel Making

Steel making routes

Basic Oxygen Steel Making (BOS)

Electric Arc Furnace (EAF)

Integrated route Re-melting Route

75-80% "hot metal" (pig iron) from the blast furnace

100% recycled scrap, solid pig iron or DRI

20-25% recycled scrap

64% of global steel production

33% of global steel production

Steel Making by

Basic Oxygen Furnace Route/

Integrated steel Plant route

Schematic diagram of Iron and steel Making (BOS)

Different sections of Integrated steel Plant

Raw Material Handling Plant (RMHP)

Coke ovens and by products handling Plant

Sinter Plant

Pellet Plant

Blast Furnace

Steel Melting Shop (SMS)

Continuous Casting

Rolling Mills ( Slabs/Blooms/Billet)

Heavy and structural Mills

Wire rod Mills/TMT Bars

Light , Medium and Merchant Mills

Area labs and Central lab for quality control

Raw Material handling Plant (RMHP)

Main equipment in RMHP

Wagon Tripler

Conveyors

Vibrating Feeders

Stackers (Single boom/Twin Boom)

Reclaimers

RMHP consists of Iron Ore Stock Pile

LUMP Stock pileCLO Stock PileFines Stock pileSinter stock Pile

Limestone stock pileBF GradeSMS Grade

Manganese ore stock pileLow grade Manganese ore

Alloying elementsFerrochromeFerro ManganeseNickelChromium

CoalImported coking coalNon coking coal

Distant view of a Wagon Tripler

Wagon Tripler in Operation

COKE OVENS AND

BY PRODUCT HANDLING PLANT

Lay out of Coke ovens

Process flow of Coke ovens

Photograph of Coke ovens

01.) Coal from the mixing and grinding plant02.) Coal bunker03.) Weighing containers04.) Charging car05.) Coke oven chamber06.) Riser07.) Regenerator08.) Transfer machine

09.) Quenching car10.) Coke wharf11.) Coke for the blast furnace12.) Dedusting of coke output13.) Coke pusher14.) Gas for the coal by products plant15.) Chimney

Cross section of a Coke oven battery

Cross section of Coke oven Battery

Coke ovens and by Product Handling Plant

Why Coking coal? To remove volatile constituents like Water, Coal

gas, Coal tar

To fuse fixed carbon and residual ash

To increase permeability of coke

To increase physical Properties of cokeWhat is Coking of coal ?

Absence of air

Temperature around 2000 Centigrade

Time Period 16 – 20 Hours

Nitrogen Quenching

Functions of coke

Produces and regenerates Reducing gases

Provides open permeable bed

Characteristics of BF Coke

Size --- 25 - 80mm Fixed Carbon --- 80 - 85% Ash --- 10 – 15 % Volatile Matter --- 2% Max Alkalies --- 0.50Max Sulphur --- 0.70Max Phosphorous --- 0.30 MaxAbrasion Index --- M10 ---10% Max

M40 --- 75-80 Min Strength after reaction- CSR – 55-60Reactivity --- CRI below 25

Yield of cokeCategory Size

(mm)Yield (%)

BF Coke 25-80 85 Blast furnaceNut Coke 15 – 25 5 Sinter Plant/

Ferro Alloy/ Pig Iron Industry

Coke Breeze

0-15 10 Sinter Plant/ Cement Industry

Adverse effects of Ash

Lowers BF Productivity

Increases Coke rate

An Increase in Ash content by 1.0% over a critical limit results in increase in coke consumption by about 5-6% and decrease in BF Productivity about 3 -6 %

Coke ovens

Incandescent coke in the oven waiting to be pushed

By products of coke ovens

Coke oven gas

Producer gas (CO +N2)

Coal Tar

Water gas (CO+H2)

Producer gas

(CO+H2+N2)

Naphtha

Kerosene

Heating oil and

Hydro carbon Gases etc.

SINTER PLANT

Sinter PlantWhat is sintering?

Process of agglomeration Feed Size --- Less than 10mm Product size --- +10mm to -80mm

Need of Sintering:

To improve the physical Properties of Iron Ore

To suit the Iron ore for Blast furnace

To improve the Blast furnace Productivity

To reduce the Flux consumption

To reduce production cost

To increase porosity/ Permeability

To desulphurise the ore/ burden

Charge Composition of Sinter Mix

Sl.No. Constituent Size Percentage

1. Iron Ore Fines -10mm 50-60

2. Coke breeze -15mm 5-10

3. Lime stone -3mm 10-15

4. Return Sinter -10mm 30-40

5. Water --- 5-10

Schematic diagram of sintering

Rate of Sintering depends on

Rate of Suction

Applied Suction

Permeability of the charge

Sintering Process

Sintering Machine

Sintering Machine in operation

Characteristics of Sinter

Shatter Index --- 90 (Min)

Tumbler Index --- 80 (Min)

Permeability --- 15-20%

Pelletisation

Pelletisation and Pellet Plant

What is Pelletisation?

Process of agglomeration Feed Size ---- 100% Less than 100 Mesh

(150Microns) 90% less than 325 mesh (47Microns) Product Size --- -20mm +6mmNeed of Pelletisation:

To improve the physical Properties of Iron Ore

To suit the Iron ore for Blast furnace

To improve the Blast furnace Productivity

To reduce the Flux consumption

To reduce production cost

To increase porosity

Process flow of Pelletisation

Process of Pelletisation

Feed Preparation

Green ball production and sizing (5-20mm)

Green ball Induration

--- Drying (400-500C)

--- Pre-heating (850-950C)

--- Firing (1250 – 1350C)

Cooling of Hardened Pellets

Charge composition of Pellet Mix

Constituent PercentageIron Ore Concentrate

90%Min

Lime 2-3%Bentonite 0.5-1.0%Coke 1-2%Moisture 5-10%Fuel Consumption 12LPT

Rate of Production of Green balls Depend on

Diameter of Disc/Drum

Angle of Inclination

Speed of Rotation

Nature and size of Feed

Rate of Feed

Rate of moisture addition

Rate of Withdrawal of Product

Disc Pelletiser

Top View and Side View of Disc Pelletizer

Characteristics of PelletsPhysical Properties

Size 9-16mm 85% MinBelow 5mm 5% Max

Bulk Density 2.00 T/m3

Tumbler Index 94.00% MinAbrasion Index 5.00%MaxGreen Compressive Strength

Dry Compression strength 4Kg/P

Cold Crushing Strength 250Kg/P MinPorosity 20.00% MinDrop Number 6-7

Characteristics of Pellets

Metallurgical Properties

Reducibility 60.00%MinSwelling Index 15% MaxMetallisation 92% MinStrength after reduction

50Kg/P

Low temperature breakdown test

+6.3mm 90.00% Min-0.50mm 5.0Max

Travelling Grate Pelletizing Furnace

Raw Materials for

Blast furnace Iron Making

Pellets

Sinter

Iron Ore - Lumps Iron Ore - FinesIron Ore - CLO

M- Coke Lime stone

Raw Materials for Iron Making

MN - Ore

Iron Ore - Specifications

Chemical and Size

Constituent Lump CLO Fines

%Fe (Min) 63.50 63.50 63.00

%SiO2(Max) 1.50 1.50 3.00

%Al2 O3 (Max) 3.00 3.00 4.00

S (Max) 0.05 0.05 0.07

P (Max) 0.05 0.05 0.07

Size (mm) 10-150 10-40 10(Max)

Physical Properties

Sl.No. Property Value1. Tumbler Index (Min)

(%+6.3mm)88.00%

2. Abrasion Index (Min) (%-0.5mm)

3. Bulk Density (Min) (T/m3)

4. Shatter Index (Min) (%+10mm)

Sl.No.

Property Value

1. Reduction Degradation Index (RDI) (%-2.8mm) (Min)

2. Thermal Degradation Index (TDI) (%-6.3mm) (Min)

3. Relative reducibility (%) (Min)

Characteristics of Sinter

Shatter Index --- 90 (Min)

Tumbler Index --- 80 (Min)

Permeability --- 15-20%

Size 10-80mm

Characteristics of BF Coke Size --- 25 - 80mm Fixed Carbon --- 80 - 85% Ash --- 10 – 15 % Volatile Matter --- 2% Max Alkalies --- 0.50Max Sulphur --- 0.70Max Phosphorous --- 0.30 Max Abrasion Index --- M10 ---10% Max

M40 --- 75-80 Min Strength after reaction- CSR – 55-60 Reactivity --- CRI below 25

Characteristics of PelletsPhysical Properties

Size 9-16mm 85% MinBelow 5mm 5% Max

Bulk Density 2.00 T/m3

Tumbler Index 94.00% MinAbrasion Index 5.00%MaxGreen Compressive Strength

Dry Compression strength 4Kg/P

Cold Crushing Strength 250Kg/P MinPorosity 20.00% MinDrop Number 6-7

Characteristics of Pellets

Reducibility 60.00%MinSwelling Index 15% MaxMetallisation 92% MinStrength after reduction

50Kg/P

Low temperature breakdown test

+6.3mm 90.00% Min-0.50mm 5.0Max

Characteristics of Lime StoneBF Grade

CaCo3 94.00% Min

SiO2 4.0%Max

MgO 3.00%Max

Al2O3 3.00%Max

MgO + Al2O3 5.00%

What is a blast furnace?

A counter current reactor lined

with Refractories to with stand

High Temperatures

Modern Blast Furnace Plant and Process

Blast Furnace Proper

Hot Blast Supply Equipment

Gas Cleaning System and Gas Storage

Dust Catcher

Scrubber

Electrostatic Precipitator

Raw material Storage and Handling

Liquid Products Disposal

Process Control Equipments

Process flow of BF Iron Making

Outer view of Blast furnace

BF – Refractory lining

Refractories used in BF

Temperature profile of BF

Cross sectional View of Modern BF

Different zones of BF

Throat – The burden surface at the top of the

Shaft - Tapering portion of the Furnace

Belly - Short Vertical Section(Bosh Parallel)

Bosh - Where the Ore reduction Completes

Hearth - Where the molten materials( Slag and

Hot Metal) are collected and Tapped

Based on Shape

Based on internal state of the Feed Materials

Primary reduction Zone (400- 1000C)

Thermal Reserve Zone (1000 – 1200C)

Cohesive zone (1200- 1400C)

Active coke zone/ Dripping Zone (1400-1750)

Dead man (1500 – 1600C)

Temperature profile and Chemical reactions in BF

Different sections of BF

BF – Pictorial View

Reactions in BF and Hot Metal Tapping

Chemical Reactions in BF

Direct Reduction

Indirect Reduction

Smelting Reduction

Reduction of Iron Ore by Solid coke

Reduction of Iron Ore by CO and CO2

Melting and Reduction of Iron Ore by CO and CO2

Direct reduction

Due to CO and H2 gas and Solid Coke Particles

Temperature --- 1100C

FeO + CO = Fe + CO2

CO2 + C = 2CO

Total FeO + C = Fe + CO

Indirect reductionHematite : Fe2 O3 + CO = 2Fe3O4 +CO2

at 500oC

Magnetite : Fe2O3 + CO = 2FeO +CO2

at 600 to 900 oC

Wustite : 2FeO + CO = 2FeO0.5 +CO2

at 1100 to 1150 oC

Zones – Reactions

Removal of Gangue/ Impurities

Gangue + Flux = Slag

Gangue elements are Silica, Alumina, Lime, Magnesia

Flux --- Lime stone/ Dolomite

Slag --- Molten oxide product of smelting

Functions of Flux

To bring down the softening the point of gangue materials

To reduce the viscosity of the slag

To decrease the activity of slag components to make them stable or unstable

Hot metal Taping from Blast furnace

Photograph of a Torpedo Ladle

Cross section of a torpedo ladle car

Hot Metal Composition

Carbon --- 3.50 to 4.50%

Silicon --- 0.50 to 2.50%

Manganese --- 0.50 to 1.50%

Phosporus --- 0.04 to 2.00%

Sulphur --- 0.04 to 0.15%

Temperature --- Around 1500C

Slag Composition

Cao --- 34 – 42%

MgO --- 6 – 12%

SiO2 --- 28 – 38%

Al2O3 --- 8 – 20%

Sulfur --- around 1%

Raw materials required for production of one Tonne of Hot Metal

Iron Ore --- 1.60 to 1.70T

Coke --- 0.70 – 0.80T

Lime Stone --- 0.40 to 0.50T

Manganese Ore --- About 50Kg

Air --- 4.50T

Standard indices for Production efficiency evolution

Parameter World (Avg)

SAIL RINL TISCO

ProductivityT/m3/Day

2-3 1.11-1.721.51

1.95 1.82

Coke rateKg/THM

350-400 498- 611538

474 528

Energy ConsumptionGCal/TCS

4-5 6.84- 8.887.5

6.32 5.28

Power Consumption(Kwh/T Sal Steel

400-500 430 – 602498

540 430

Refractory ConsumptionKg/TCS

15 14.9 – 20.018.2

18.5 13.6

BF Techno Economic Parameters

Dimensions of Largest in the world

Volume --- 5500 cu.m

Height --- 60m

Hearth Diameter--- 15.6m

Bosh Dia --- 13.5m

Throat dia --- 7.50m

No. Of Tuyers --- 32

No. of Sinder notches--- 12

Productivity --- 13,500 TPD

Productivity --- 2.00- 2.50 T/m3/D

Irregularities in BF practice

Hanging

Scaffolding

Chilled Hearth

Pillaring

Breakout

Choking of Gas off take

Flooding and Coke ejection through tap holes

Leaking Tuyeres, Tap holes and coolers

Channeling

Modern trends in BF Practice

Large Capacity Furnaces Better prepared burden (Ore/Coke) Better Charge distribution High Top Pressure Higher blast rate and temperature Oxygen enrichment of blast Humidification of blast Auxiliary fuel injection through tuyeres Blast furnace gas injection in the stack Lime dust injection through the tuyeres

Steel Making by LD Converter

Process

LD Converter

Oxygen steel making Process Modification of Bessemer Process Named after two cities in Austria, LINZ

and DONAWITZ Steel is produces by oxygen lancing

and removes impurites like C, Si, Mn, Ca and Mg

Oxygen lancing time 30 - 50minutes More than 60% of steel is made in this

Percentage Hot Metal SteelFe 94.00Min 99.40MinC 0.70-1.50 0.30 – 0.60Si 0.30- 0.70 0.01- 0.03Mn 0.20 -0.40 0.05 – 0.10P 0.06 - 0.13 0.01 – 0.03S 0.06 -0.12 0.01 – 0.03

Chemical Analysis of Hot metal and Steel

Reactions in the LD Converter

Si + O2 = SiO2

S + O2 = SO2

C + O2 = Co2

2C + O2 = CO

4P + 5O2 = 2P2 O5

Conduct of oxygen blowing (slag formation for good dephosphorization, avoid slopping, spitting, iron losses, etc.) Accurate determination of end point

(C,T) Good management of charging, tapping and of the equipment.

Main control parameters

Slag/Metal Reactions Slag/metal reactions concern:

Si removalThis reaction is very fast and the total amount of silicon is transferred to the slag in the first one third of the blow

P and S removalThese reactions require a very accurate control of slag formation and of the final slag composition in order to guarantee the low contents sought for the liquid steel.

Of the two, dephosphorization is the most crucial and is analyzed here. To be successful and cost efficient, the steelmaker has to consider both thermodynamic and kinetic aspects.

Slag Treatment BOF slag is generated at a rate of 60 to 100 kg per tonne

of steel. After steel tapping, it is poured in a slag pot by tilting the converter and dumped in the slag yard from which it can be reclaimed.

Currently, about half of this quantity gets recycled internally, either in the sinter plant or else used directly in the blast furnace. The valuable elements thus recovered are Fe and CaO. Such in-plant slag recycling has been declining because of higher steel quality demands, e.g. lower phosphorus.

Other uses such as landfill, aggregate and agricultural purposes are being explored.

LD Converter- Accessories

LD Converter Steel Making

LD Converter – Cross section and reactions

1. Long Life in Heats.2. Easy to charge.3. Controlled Tapping Time.4. Improved Quality of Tapped Steel.5. Much less down time for Tap hole Maintenance.6. Reduction in Specific Cost.

LD Converter --- Advantages

Property Value

Specific Gravity > 3.2 - 3.6

Unit Weight, kg/m3 (lb/ft3)

1600 - 1920(100 - 120)

Absorption up to 3%

Typical physical properties of steel slag.

Constituent Composition (%)CaO 40 - 52 SiO2 10 - 19

FeO10 - 40

(70 - 80% FeO, 20 - 30% Fe2O3)

MnO 5 - 8MgO 5 - 10Al2O3 1 - 3P2O5 0.5 - 1

S < 0.1Metallic Fe 0.5 - 10

Typical steel slag chemical composition.

Secondary steel Making

Route --- Electric Arc Furnace

Capacity --- 1T to 400T

Feed --- Iron Ore, Pellets and

Steel Scrap

Temperature--- 1800C

EAF Steel Making

Steel Making - Electric Arc Furnace

Steel making Next steps

Continuous casting of

Steel making next steps

Continuous castingBlooms/SlabsBilletsHot rollingCold RollingForgingCastingHeat treatmentFinished/Semi finished goods

Principle of Continuous Casting

Continuous Casting

Principle of Continuous Casting

Photograph of Continuous casting in VSP

Photograph of Continuous casting

Photograph of slab casting

Photograph of Slab casting

Rolling Mills

Rolling

Hot rolling Cold Rolling

Above recrystalisation temperature (1100C)

Room temperature and in some special cases up to 300C

Process of Hot rolling

Various rolling configurations

A. 2-high B. 3-high C. 4-high D. 6-high E&F. Cluster

Rolling Mills strand arrangement

Rolling Blooms to Billet

Rolling Process

Hot Rolled Product (Billet)

Photograph of wire rod drawing

Drawing of Rails

Finished products ready for dispatch

Any Questions ?

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