steel making and the next steps
TRANSCRIPT
WELCOME TO
QUEST
Steel Making and the next steps
By
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
1950
-51
1960
-61
1970
-71
1980
-81
1990
-91
1999
-200
0
2000
-200
1
2003
-200
4
2004
-200
5
2005
-200
6
2006
-200
7
2007
-200
8
2008
-200
9
2009
-201
00
10
20
30
40
50
60
70
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
Year
Mill
ion
To
nn
es
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
Fuel
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 (%)
Use
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
1Kg/P
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
Iron Ore - Specifications
Sl.No. Property Value1. Tumbler Index (Min)
(%+6.3mm)88.00%
2. Abrasion Index (Min) (%-0.5mm)
5.00%
3. Bulk Density (Min) (T/m3)
2.00
4. Shatter Index (Min) (%+10mm)
85.00
Iron Ore - Specifications
Metallurgical Properties
Sl.No.
Property Value
1. Reduction Degradation Index (RDI) (%-2.8mm) (Min)
20.00
2. Thermal Degradation Index (TDI) (%-6.3mm) (Min)
9.00
3. Relative reducibility (%) (Min)
45.00
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
1Kg/P
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
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
Cross sectional View of Modern BF
Different zones of BF
Throat – The burden surface at the top of the
BF
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
Different zones of BF
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)
Different zones of BF
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
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
Slip
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
route
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
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 Continuous casting
Photograph of Continuous casting
Photograph of slab 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
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
Finished products ready for dispatch
Finished products ready for dispatch
Finished products ready for dispatch
Finished products ready for dispatch
Finished products ready for dispatch
Finished products ready for dispatch
Finished products ready for dispatch
Finished products ready for dispatch
Any Questions ?
WELCOME
TAN Q