MM3020: Iron making and steelmaking (2012-13-II)

Instructor In charge: Dr. Ajay Kumar ShuklaDepartment of Metallurgical and Materials EngineeringIIT Madras, India

Learning Objectives To apply the principles of physical chemistry and transport

phenomena (heat, mass and momentum) to the process steps in Ironand Steelmaking as practiced in integrated steel plants.

Be able to understand basic layout of blast furnace, steelmaking shop and continuous casting process.

To develop computational and mathematical abilities to be applied for process design and control. It may be C++, MATLAB, Excel-Solver, FlowBal, FactSage or any other language of interest.

Be able to model, optimize and control various reactors involved in steel plant supply chain.

Be able to function in an integrated steel plant/corporate center and R&D ventures

Text books: • Ironmaking and Steelmaking: Theory vs. Practice: Ahindra Ghosh and Amit

Chatterjee• Principles of Blast Furnace Ironmaking: A.K. Biswas• Fundamentals of Steelmaking Metallurgy: Brahma Deo, Rob Boom• Fundamentals of Steelmaking: E.T. Turkdogan• Physical Chemistry of melts in Metallurgy: F.D. Richardson Marks distribution (All exam problems will be computational in nature)• Quiz 1: 10%• Quiz 2: 10%• Assignments: 20%• Term project: 10%• Final Exam: 50% Assignments

One every week. Students may use computer coding/techniques to solve them. It is advised to solve the assignment problems by their own if want to perform well in exams.

Attendance• There is no weightage for the attendance.• Since the course involves a lot of computational work and fundamental

understanding about various principles which would be difficult to understand for those who miss the classes. It would be in the interest of the all the students to attend all the classes if they want to score enough to pass the course.

What is steel ? Steel is a metallic material. Metals are classified in two categories:

Ferrous vs Non-Ferrous

Steel is Fe+C+……….

It is subsequently catagorized as plain carbon steel and alloy steel

Plain carbon steel: Low carbon (C< 0.3%, Medium carbon (0.3-0.6%), High Carbon(0.6-1.0%)

Plain carbon steel contains C, Si, Mn, S, P, N, O ,H… as dissolved elements.

Alloy steels contains other elements in addition to them depending upon requirements like Ni, Cr, Nb, Co, Ti ,B, Mo,W etc.

Steel exhibits a wide range of mechanical properties depending upon its composition and heating-cooling cycles (Heat-treatment)

Knowledge of Fe-C phase diagram, CCT, TTT is required to predict the desired processing in order to obtain desired microstructure forspecific mechanical properties

Fe-C, TTT an CCT diagramCourtesy: msm.co.uk

Applications of steel Steel is the most widely used material in the world in Automative,

Construction, Engineering, Packaging and Offshore application

Usage comparison (yearly)Steel: 1400 MT, Aluminum : 40 MT, Copper: 16 MT, Zinc: 10.6 MT, Lead 7 MT, Nickel: 1.7 MT, Magnesium: 0.8 MT, Titanium: 0.15 MT

Low carbon steel application: Flat rolled products like Automobiles, Seamless tubes

Medium carbon steel application: Shafts, coupling, crank shafts

High carbon steels: springs, high tension wires

Suggested readings: www.steeluniversity.org, www.worldsteel.org

Worldwide steel production and India's position

In 2011 total steel production of entire world was 1490 MT. India produced 72 MT (5% contribution).

Per capita steel consumption is the index of prosperity of any country. World per capita steel consumption is 215 kg. India has approx. 50 kg per capita consumption.

India has projected to produce 140 MT by end of 2016-17.

China with same population as India is producing 683 MT (highest in world).

India has to go up to 1000 MT with current population in order to be ranked in developed nations.

Therefore Steel industry is a booming industry for next 30-40 years in India.

More information on world statistics of steel production please go through : www.worldsteel.org and website of planning commission india

Iron and Steelmaking process routes

What is needed to know: Layout of the entire plant and design aspects of the

processes Physicochemical aspects of the process:• Type of reactions• Thermodynamics and equilibrium systems of

importance• Kinetics, heat and mass transfer Phase diagrams (esp. for slag systems) Raw materials properties Process control models: Static vs Dynamic vs Data

driven Optimization of a process or entire steel plant supply

chain (with objective of minimum cost/maximum profit)

Automation control hierarchy of large scale steel plant

Blast furnace ironmaking

• Carbothermic reduction of iron ore (Hametite) in blast furnace is a well known process. Overall process is written as:

• Ironore oxide mineral + gangue + Reducer (C) + flux + hot blast oxygen enriched air = Pig iron (liquid) + Slag (liquid) + waste gas (CO,CO2,N2)

• Iron ore contains Fe2O3, along with gangue materials such as SiO2, Al2O3.

• Charge materials are: Iron ore + limestone (flux) + Coke• Output is

pig iron (1300 C), 4.5% C, 0.4-0.6% Si, 0.1-0.2% P, 0.040-0.050% S, 0.1-0.5% MnSlag: CaO/SiO2 = 1.1; CaO = 30-40%; Al2O3 = 10-23%; FeO<1%; MgO <8%Waste Gas: CO = 20-25%, CO2 = 20-25%, rest N2

Blast furnace layout with auxillaryequipments

Reaction zones in a blast furnace

a) Gas temperature along stackb) Reduction zones along stackc) Carbon reduction degree (O/Fe) with stack height

Chemical reactions in a blast furnace

Zone 1 (<950 C),upper zone of stack, reduction of Fe2O3,Fe3O3 takes place:3Fe2O3(s) + CO 2Fe3O4(s) + CO2Fe3O4(s)+CO 3FeO(s) + CO2

Zone 2 (950-1000 C), chemical reserve zone, FeO is in equilibrium with gaseous phase:FeO(s) + CO = Fe(s) + CO2

Zone 3: (950<T<1050 C), the reduction of FeO by rising CO gas takes place:FeO(s)+COFe + CO2

Zone 4: (>1000-1050C), direct reduction of FeO to carbon takes place. Reaction in raceway zone: C+ O2 CO2

followed by CO2 + C 2CO (Boudward reaction)Overall C + O2 = 2CO

Boudward reaction is thermodynamically feasible at T >1050 (below zone 4). It supports the conversion of CO2 to CO in raceway and bosh region where T>1050 C.