1. HYDROGEN CONTROL OF LARGE BOTTOM POURED FORGING INGOTS AT ELLWOOD QUALITY STEELS
Bjorn Gabrielsson – Ellwood Group, Inc.
Brendan Connolly – Ellwood Quality Steels
Steve Lubinski – Ellwood Quality Steels
Sean Cowden – Ellwood Quality Steels
Hongliang Yang – ABB R&D Metallurgy

2. Outline Evolution of vacuum treatment of liquid steel
New Castle Complex
EQS Production Flow and KPI
Sandwich Pouring of Ingots >47 Mton
Hydrogen in Steel
EQS Vacuum Station
CFD Simulation
Model Validation
Hydrogen Pick-up during Bottom Pouring
Conclusion

3. Revolution of Vacuum Treatment of Liquid Steel
German chemist Albert Sievert published his work on the solubility of gases in metal
1950 Bochumer-Verein (Germany), first vacuum tank FAILED
1952 Bochumer-Verein (Germany), first stream degassing
1955 Air Liquide (France), development of porous plug
1956 Bethlehem Steel (USA), first multi-stage steam ejector vacuum pump
1958 Finkl (USA), VTD with He inert gas lance stirring
1959 Dortmand-Hoerder vacuum lift process (Germany)
1959 Ruhrstahl-Heraeus vacuum lift process (Germany)
1964 Germany/USA simultaneously developed ladle slide gates
1965 ASEA-SKF Process (Sweden), vacuum treatment with electromagnetic stirring
THE REST HAS JUST BEEN A LONG EVOLUTION

4. New Castle, PA Complex

5. New Castle, PA Complex

6. EQS Production Flow and KPI
Value
EAF Gross T-T-T
52.7 minutes/heat
EAF Power On Time
36.1 minutes/heat
EAF Power Off Time
16.6 minutes/heat
Productivity
27.3 heat/day
Dec 1985 – August 2018 more than 8,300,000 Mton of forging and ring rolling ingots

7. Sandwich Pouring Process for Ingots >47 Mton
Implemented at EQS in 2015
Up to four ladles of steel into one ingot
Maximum ingot produced to date 170 Mton with 4x ladles

8. Hydrogen in Steel

9. Hydrogen in Steel

10. EQS Vacuum Station

11. CFD Simulations PARAMETER CASE 1 CASE 2 CASE 3 Heat size, Mton 45
EMS type
None
ORT34
EMS Current, A
1000
1350
EMS stir direction Up
Vacuum pressure, mbar
1.0
Ar flow rate, Nl/min 80
Slag amount, kg
600

12. CFD Simulations
R/2

13. CFD Simulations – Top Surface Velocity
m/sec
m/sec
m/sec

14. CFD Simulations – Bulk Metal Velocity

15. CFD Simulations – Argon Bubble Dispersion and Velocity
m/sec
m/sec
m/sec

16. CFD Simulations - Summary
RESULT
CASE (Ar-gas only)
CASE (Ar-gas A EMS)
CASE 3
(Ar-gas A EMS)
Stirring power density, W/ton 65
600
700
Free metal surface, %
7.4
22.5
27.9
Average surface velocity, m/s
0.14
0.41
0.53
Average bulk metal velocity, m/s
0.11
0.48
0.71
Bubble dispersion and residence time
Low
Medium
High
Thanks to increased stirring power:
Free metal surface 3.8 times larger
Surface velocity 3.8 times larger
Bulk metal velocity 6.5 times larger
Argon bubble dispersion and retention time improved significantly

17. Model Validation – Mixing Time

18. Model Validation – Free Metal Surface

19. Model Validation – Hydrogen Results

20. Hydrogen Pickup – Secondary Steelmaking
Comparison of H pickup for heats tested after vacuum treatment and heats tested just before bottom pouring
On average <0.1 ppm difference – virtually no H pickup during secondary steelmaking

21. Hydrogen Pickup – Data Analysis
Data collection for > 30,000 heats produced at EQS
Level 2 process control system combined with “Business Intelligence” software for massive data mining
Analysis of in-process and final hydrogen content against large set of possible variables

22. Hydrogen Pickup – Ladle Refractories
5+ heats on all components = baseline (0% contribution to hydrogen pickup)
Non-shrouded heats excluded, Total 34,519 heats

23. Hydrogen Pickup - Atmosphere
100% reference is average of 20,338 shrouded heats produced since Ar-shroud upgrade (2015)
Non-shrouded heats total 1,939 over same time period

24. Hydrogen Pickup – Bottom Pour Tile Mortar

25. Hydrogen Pickup – Teeming Flux

26. Ultra Low Hydrogen Practice
Careful ladle planning ensures inner nozzle, slide gate and collector nozzle are not new
Vacuum treatment at < 1 mbar with combined EMS and Ar-gas stirring
Strict limitation on alloying and slag additions after vacuum treatment
Argon Shrouding of the lower ladle stream
Ladle-to-ladle shrouding of the upper ladle stream(s)
Preheating of bottom pour refractory to 500°C
Preheating of ingot mold
Flux addition by direct pouring into hot mold for residual moisture removal
AVERAGE OF 35% REDUCTION IN HYDROGEN PICKUP

27. Conclusion

28. THANK YOU FOR YOUR KIND ATTENTION