1. Inox Group #3
Mohammed Abu Sharkh
Spencer Brennan
Saikat Chanda
Michael Garibaldi
Production of Stainless Steel
Design Project II: Final Presentation
April 23rd, 2014

2. Mandate & Scope
• Mandate:
• 2 million tonnes of stainless steel slabs
• 600,000 tonnes of high carbon ferrochromium from group 1
and group 2
• Desired stainless steel compositions: maximum 0.08wt%
carbon, 18wt% chromium and 8wt% nickel
• Project scope:
• High carbon ferrochromium, ferronickel, ferrosilicon, iron
ore and steel scrap are the major raw materials
• Production of stainless steel slabs with dimensions 10 m x
1 m x 0.25 m
• Recycle and treatment of off-gas
Stainless Steel Production 2

3. Process Description
1.Midrex Direct Iron Reduction
• Gas-based iron ore reduction
• Syngas production
2.Electric Arc Furnace
• Decrease carbon and gangue material content
3.Argon Oxygen Decarburizer
• Decrease carbon content
• Increase chromium content
• Nickel addition
4.Continuous Casting
• Cooling and compression casting of metal slabs
Stainless Steel Production 3

4. Block Flow Diagram
Stainless Steel Production 4
Midrex
Process
Electric
Arc
Furnace
Argon
Oxygen
Decarburizer
Continuous
Casting
Iron Ore, Water,
Natural gas, air,
CO from
group#2
DRI Steel
Stainless
Steel
Steel Scrap , Lime,
Atmospheric Air
Oxygen, Argon, HCFeCr,
FeNi40, Flux(FeSi +
CaO) Cooling Water, Process Water,
Atmospheric Air
Off-Gas
Slag
Effluent To waste water
Air
Stainles
Steel
Slabs
Off-Gas

5. Midrex Process: Overview
• Process Objectives:
• Decrease oxygen Wt% in iron ores from
30% 3%
• DRI containing 1.6 Wt% Carbon
• Produce 1 million tonnes per annum direct
reduced iron (DRI)
• Hot charged to EAF at 650oC
• Iron ore pellets provide 65% of the total
iron content of stainless steel
•
Stainless Steel Production 5
Iron ore
Pellets
DRI Source: Siemens.com, 2014

6. Midrex Process: Shaft Furnace & Steam
Reformer
• 2 main units:
• Shaft furnace for iron reduction:
• Fe2O3 + 3H2 → 2Fe + 3H2O
• Fe2O3 + 3CO → 2Fe + 3CO2
• 2 hours residence time
• Steam reformer for syngas production:
• CH4 + H2O → CO + 3H2
• CH4 + CO2 → 2CO + 2H2
• Combustion of natural gas used to heat
feed reactants to 900oC and for
endothermic reactions
Stainless Steel Production 6
Source: ThyssenKrupp, 2014

7. Midrex Process: Reformer PFD
Stainless Steel Production 7

8. Midrex Process: Shaft Furnace PFD
Stainless Steel Production 8

9. Midrex Process Overview
Input
Iron Ores (tons/yr) 1.4 million
Syngas (tons/yr) 890,000
Output
DRI (tons/yr) 1 million
Dimensions
Shaft Furnace total
Height (meters)
26.7
Shaft Furnace
Internal Diameter
(meters)
6.5
# of Reformer Tubes 378
Power Requirments
Shaft Furnace
(MW)
75
Reformer (MW) 102
Stainless Steel Production 9
Costs Dollars (US $)
CAPEX 85,056,000
OPEX 235,072,000
OPEX (per tonne
Stainless Steel)
118.00

10. ElectricArc Furnace: Overview
• Process Objectives:
• Reduce Fe
• Fe3C, FeO → Fe
• Oxidize C
• 1.6 wt% to 0.99 wt%
• Remove oxides
• SiO2, MgO, P2O5, TiO2, Na2O
Stainless Steel Production 10
REACTANTS PRODUCTS
1 Fe3C 3 Fe, 1 C
1 FeS + 1 CaO 1 FeO + 1 CaS
1 FeO + 1 C 1 Fe + 1 CO
Source: Midrex Technologies, 2013

11. Electric Arc Furnace: Overview
Stainless Steel Production 11

12. Electric Arc Furnace: PFD
Stainless Steel Production 12

13. ElectricArc Furnace: Overview
INPUT OUTPUT
Stainless Steel Production 13
DRI Lime Steel
Scrap
Air
wt% wt% wt% wt%
Mass
Rate
Tonnes/
year
1,016,174 60,000 150,000 51,141
Fe 68.65 0 96.85 0
Fe3C 23.92 0 0 0
FeO 3.00 0.61 0 0
C 0 0 1.35 0
SiO2 2.29 2.58 0.06 0
FeS 0.0085 0 0 0
CaO 0.79 94.5 0 0
O2 0 0 0 21
N2 0 0 0 79
Steel Slag Off-Gas
wt% wt% wt%
Mass
Rate
Tonnes/year 1,094,550 112,125 70,640
Fe 98.93 0 0
FeO 0 6.27 10.89
C 0.99 0 0
SiO2 0.08 20.41 0.39
CO 0 0 26.89
MgO 0 4.49 0.41
CaO 0 57.09 1.00
Units Value
Power MWh 186
Cooling Requirements MJ/h 322
CAPEX $ 83,704,400
OPEX $/tonne steel 89

14. Argon Oxygen Decarburizer: Process
Overview
• Process Objective:
• Reduce the Carbon content from
1 to 0.08 wt%
• Add Nickel and Chromium to the
final Stainless Steel Slabs
• Operating temperature:
• 1600 - 1800 ⁰C
• Regain iron and chromium
from slag
Stainless Steel Production 14
Source: SMS-Demag

15. Argon Oxygen Decarburizer
Stainless Steel Production 15
• Main Reactions:
• C + ½ O2 → CO
• Si + O2 → SiO2
• 2Fe + O2 → FeO
• 2Cr + 3/2O2 → Cr2O3
• FeSi + 2FeO → 3Fe + SiO2
• Cr2O3 + 3/2FeSi →2Cr + 3/2SiO2 + 3/2Fe
• Oxygen : Argon = 3:1 (@ the
beginning)
• Oxygen : Argon = 1:3 (@ the end)
• Argon added to prevent unwanted
oxidation
• Process time: 1 hour
Source: MSTS

16. Argon Oxygen Decarburizer: PFD #1
Stainless Steel Production 16

17. Argon Oxygen Decarburizer: PFD #2
Stainless Steel Production 17

18. Stainless Steel Production 18
Argon Oxygen Decarburizer:
Overview
Input
Compounds Value
Steel (From EAF)
(t/annum)
1,094,500
High Carbon
FerroChrome (HCFeCr )
(t/annum)
600,000
Ferronickel (FeNi40)
(t/annum)
400,000
Oxygen (m3/annum) 47,663,000
Argon (m3/annum) 106,673,000
Flux (FeSi + CaO)
(t/annum)
200,900
Output
Compounds Value
Stainless Steel
(t/annum)
2,020,000
Off-Gas (t/annum) 278,000
Slag (t/annum) 251,000
Significant Items Value
Energy Requirement (MWh) 0.2
CAPEX ($US) 290,764,000
OPEX ($US per tonne
Stainless Steel) 1684.00

19. Continuous Casting
• Process objective:
• molten stainless steel
solidification into a
continuous strand where it is
cut into slabs
• Storage of stainless steel
in tundishes converts
entire batch process to
continuous
• Two casting machines in
operation due to casting
speed restriction
Stainless Steel Production 19
Source: http://www.isam-ag.com/casting

20. Continuous Casting: Casting
Stainless Steel Production 20

21. Continuous Casting: Flux & Molten Addition
Stainless Steel Production 21

22. Continuous Casting: Water Cooling
Stainless Steel Production 22

23. Continuous Casting: Blowing + Inventory
Stainless Steel Production 23

24. Continuous Casting: Cooling Overview
Stainless Steel Production 24

25. Overall Top View Plant layout
Stainless Steel Production 25

26. Overall Side View Plant Layout
Stainless Steel Production 26

27. Environmental Evaluation
• 85% of CO provided from group 2 and off-gases
• 15% of total CO2 is recycled for syngas production
• 0.8 tonnes of CO2 per ton DRI
• Required bag house to meet particulate matter emission
limit
Stainless Steel Production 27
Allowable
(mg/m3 per 8 hours)
Allowable
(kg/day)
Emitted
(kg/day)
CO 55 1294 0
SO2 13 306 0.06
P2O5 1 24 0.20
SiO2 30 706 9.92
PM 15 353 504
Flow rate (m3/day) 7839513

28. Control Philosophy
• Ensures the timely production of 2 million tonnes of
stainless steel per annum safely from a batch to
continuous process
• Semi-batch process operating via tapping until the ladle is
discharged into the tundish
• All vital supporting operating units have redundancies
• Controllers are wired to the central control room
• Alarms are installed at sensitive measurement sites
Stainless Steel Production 28

29. Continuous Casting: Tundish Discharge
Control
Stainless Steel Production 29

30. Annual Economic Breakdown by
Group
• The majority of the revenue comes from selling
stainless steel slabs
• Procurement of ferronickel drives the operating
expenditures of Group 3 up
Stainless Steel Production 30

31. Economic Analysis
• Depreciation (declining balance) of all assets - 10% per annum
• Corporate tax rate - 40%
• The investment - 100% equity
• Cost of capital -10%
• Non-integrated taxation method with depreciation losses not
allowed
• Total capital investment of the plant equally split over the first
three years of pre-production
• Total project lifespan - 20 years
Stainless Steel Production 31