Inox Group #3 Mohammed Abu Sharkh Spencer Brennan Saikat Chanda Michael Garibaldi Production of Stainless Steel Design Project II: Final Presentation April 23 rd , 2014
Inox Group #3Mohammed Abu SharkhSpencer BrennanSaikat ChandaMichael Garibaldi
Production of Stainless SteelDesign Project II: Final Presentation
April 23rd, 2014
Stainless Steel Production 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 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 4
Block Flow Diagram
Midrex Process
Electric Arc
Furnace
Argon Oxygen
Decarburizer
Continuous Casting
Iron Ore, Water, Natural gas, air,
CO from group#2
DRI SteelStainless
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
Stainless Steel Slabs
Off-Gas
Stainless Steel Production 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
• Iron ore Pellets
DRI Source: Siemens.com, 2014
Stainless Steel Production 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
Source: ThyssenKrupp, 2014
Stainless Steel Production 7
Midrex Process: Reformer PFD
Stainless Steel Production 8
Midrex Process: Shaft Furnace PFD
Stainless Steel Production 9
Midrex Process OverviewInput
Iron Ores (tons/yr) 1.4 million
Syngas (tons/yr) 890,000
Output DRI (tons/yr) 1 millionDimensions
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
Costs Dollars (US $)
CAPEX 85,056,000
OPEX 235,072,000
OPEX (per tonne Stainless Steel) 118.00
Stainless Steel Production 10
Electric Arc 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
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
Stainless Steel Production 11
Electric Arc Furnace: Overview
Stainless Steel Production 12
Electric Arc Furnace: PFD
Stainless Steel Production 13
Electric Arc Furnace: OverviewINPUT OUTPUT
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 $/tonne steel 89
Stainless Steel Production 14
Argon Oxygen Decarburizer: Process Overview
• Process Objective: • Reduce the Carbon content from
1 to 0.08 wt%• Add Nickel and Chromium to the
final Stainless Steel Slabs
• Operating temperature:• 1600 - 1800 ⁰C
• Regain iron and chromium from slag
Source: SMS-Demag
Stainless Steel Production 15
Argon Oxygen Decarburizer• Main Reactions:
• C + ½ O2 → CO• Si + O2 → SiO2
• 2Fe + O2 → FeO• 2Cr + 3/2O2 → Cr2O3
• FeSi + 2FeO → 3Fe + SiO2
• Cr2O3 + 3/2FeSi →2Cr + 3/2SiO2 + 3/2Fe
• Oxygen : Argon = 3:1 (@ the beginning)
• Oxygen : Argon = 1:3 (@ the end)• Argon added to prevent unwanted
oxidation• Process time: 1 hour Source: MSTS
Stainless Steel Production 16
Argon Oxygen Decarburizer: PFD #1
Stainless Steel Production 17
Argon Oxygen Decarburizer: PFD #2
Stainless Steel Production 18
Argon Oxygen Decarburizer: Overview
Input
Compounds Value
Steel (From EAF) (t/annum) 1,094,500
High Carbon FerroChrome (HCFeCr )
(t/annum) 600,000
Ferronickel (FeNi40) (t/annum) 400,000
Oxygen (m3/annum) 47,663,000
Argon (m3/annum) 106,673,000
Flux (FeSi + CaO) (t/annum) 200,900
Output
Compounds ValueStainless Steel
(t/annum) 2,020,000
Off-Gas (t/annum) 278,000
Slag (t/annum) 251,000
Significant Items ValueEnergy Requirement (MWh) 0.2
CAPEX ($US) 290,764,000OPEX ($US per tonne
Stainless Steel) 1684.00
Stainless Steel Production 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
Source: http://www.isam-ag.com/casting
Stainless Steel Production 20
Continuous Casting: Casting
Stainless Steel Production 21
Continuous Casting: Flux & Molten Addition
Stainless Steel Production 22
Continuous Casting: Water Cooling
Stainless Steel Production 23
Continuous Casting: Blowing + Inventory
Stainless Steel Production 24
Continuous Casting: Cooling Overview
Stainless Steel Production 25
Overall Top View Plant layout
Stainless Steel Production 26
Overall Side View Plant Layout
Stainless Steel Production 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
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
Stainless Steel Production 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 29
Continuous Casting: Tundish Discharge Control
Stainless Steel Production 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 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