2. 3rd International Iron and Steel Symposium (UDCS’17)
3 – 5 April 2017, Karabük University
Effects of Slag Optimization on Steel Cleanliness in Secondary Metallurgy Process
Emre ALAN
Steelmaking and Casting Tech.
R&D Department
Ereğli Iron and Steel Works, Co. (Erdemir)

3. Erdemir Group Companies and Products
employees
11,2 million tons of crude steel capacity

4. Erdemir Group Companies and Products
Steelmaking Plants
Products
Flat Products
Plate
Hot rolled coil and sheet
Cold rolled coil and sheet
Tinplate
Galvanised
Electrical Steel
Long Products
Billets
Wire Rod
Other Group Companies
ERDEMİR MADEN (Mining)
ERDEMİR-RO (Electrical Steel Plant, Romania)
ERSEM (Steel Service Center)
ERDEMİR Engineering and Consulting Co.
ERDEMIR ASIA Pasific PTE LTD.

5. Erdemir R&D Center
R&D Organization Chart

6. Outline
Introduction
Experimental
Results
Conclusion

7. Slag in Steelmaking
Steelmaking slags are by-products of smelting and refining proesses of liquid steel in high temperatures and they consist of a mixture of various oxides.
The role of slag in steelmaking process;
acts as a thermal barrier to prevent heat transfer from liquid steel to surrounding,
protects liquid steel from re-oxidation,
Absorbs non-metallic inclusions and provides steel cleanliness, etc.
Ladle slag in steelmaking process.

8. Non Metallic Inclusions (NMIs)
Non metallic inclusions (NMIs) are chemical compounds that are formed in steel making process such as oxides, sulfides, nitrides, etc.
The term of “clean steel” should mean a steel free of non-metallic inclusions.
There are generally two sources of inclusions in steel;
Exogenous
Usually larger in size, are results of reoxidation, slag entrainment and refractory erosion.
Indigenous
Generally smaller in size, are results of chemical reactions; deoxidation, etc.
Depending on their size, distribution and morphology NMIs may cause adverse effects on;
Mechanical properties like strength and fatigue,
Machinability
Nozzle clogging in continuous casting process
Surface polishing and finishing
Welding properties
Magnetic properties

9. Steelmaking Process Route
Tapping
Alloying addition
Flux addition
BOF Process
LF Process
Continuous Casting
Homogenization
Heating
Alloying addition
Inclusion removal

10. Tapping Addition Practice
Experimental
In this study, the effects of different tapping addition practices were compared in order to produce a cleaner steel.
TABLE I Comparıson of Tappıng Addıtıons
Tapping Additions
[kg]
Tapping Addition Practice
Regular
Trial
Ferro Manganese [H.C]
1550
Ferro Silicomanganese
1500
1700
Calcium Fluorite
100 -
Calcium Aluminate
550
Lime
1350
1100
Aluminium [Ingot]
350 80

11. (a) regular and (b) trial heats.
Results
Computational Thermodynamic Studies
Ternary phase diagrams of ladle furnace slags plotted by using FactSage Computational Thermodynamic Software;
(a) regular and (b) trial heats.

12. Results Secondary Metallutgy Process Conditions LF Process
TABLE III Comparıson of feot and mno Contents ın Ladle Slags Accordıng to Tappıng Addıtıon Practıces
Sample
Component [%]
FeOt
MnO
BOF Slag
20,4
3,8
Regular
1,5
0,8
Trial
0,6
0,1
CaSi wire
Alloying Addition
Steel sample
LF Process
[S] content in secondary metallurgy process.
Addition practices in secondary metallurgy process.

13. Results Spark-DAT/OES Investigations
CaS inclusions in liquid steel according to S content before CaSi wire injection.
ARL Spark-DAT/OES analyzing instrument and methodology.
Comparison of total non-metallic inclusions after secondary metallurgy process.

14. (a) regular and (b) trial heats.
Results
Optical Microscopy Investigations
Optical microscopy images with 100X magnification of samples taken from end of secondary steelmaking process;
(a) regular and (b) trial heats.

15. Conclusion
In this study, the effects of different tapping additions to ladle slag conditions and steel cleanliness were investigated.
In trial heats, increasing of Al2O3 content of slag in tapping process provided an increment in fluidity of initial ladle slag by dissolving over-saturated CaO content.
Slag deoxidation was applied by adding Al onto slag to obtain lower FeOt content in initial ladle slag. Therefore, the desulphurization efficiency of slag is increased by obtaining a proper slag formation, increasing slag basicity and reducing FeOt content in trial heats.
It was observed that the total number of detected non-metallic inclusions were reduced after secondary metallurgy process by reducing the amount of addition materials in secondary metallurgy process by increasing the addition amounts during tapping.

16. Thanks for Your Attention.