Presentation is loading. Please wait.

Presentation is loading. Please wait.

Study of kinetics of Inclusions Transformations in Ladle Metallurgical Furnace for the Production of LCAK Steels Departmental Seminar Presentation Mahshid.

Similar presentations


Presentation on theme: "Study of kinetics of Inclusions Transformations in Ladle Metallurgical Furnace for the Production of LCAK Steels Departmental Seminar Presentation Mahshid."— Presentation transcript:

1 Study of kinetics of Inclusions Transformations in Ladle Metallurgical Furnace for the Production of LCAK Steels Departmental Seminar Presentation Mahshid Fathi- May 27/2011 1

2 Outline Objectives Objectives Introduction Introduction –Ladle Metallurgical Furnace –Non Metallic Inclusions and Inclusion Engineering Literature Review: Literature Review: –Role of slag on formation of spinels Experimental results Experimental results Summary Summary Future work Future work Acknowledgement Acknowledgement 2

3 Objectives Investigation of the impact of processing parameters on the kinetics of transformations of inclusions formed after deoxidation of the LCAK steels and during the Ca treatment in full scale Industrial Ladle. Investigation of the impact of processing parameters on the kinetics of transformations of inclusions formed after deoxidation of the LCAK steels and during the Ca treatment in full scale Industrial Ladle. Development of a mathematical model for the kinetics of inclusions transformations Development of a mathematical model for the kinetics of inclusions transformations –With focus on Spinels and calcium aluminates Validation of the model by experimental results. Validation of the model by experimental results. 3

4 4 Significant control challenges: -Elevated temperatures -Dusty environment -Electrical arcing -Complex multi component slag/metal systems Ladle Metallurgical Furnace

5 5

6 Non Metallic Inclusions during refining Oxides and sulfides Oxides and sulfides Mostly oxides, deoxidation products Mostly oxides, deoxidation products By adding Al in LCAK steels By adding Al in LCAK steels Initially Al 2 O 3 oxide Particles Initially Al 2 O 3 oxide Particles –High melting point, solid (above 2000C) Remain in the steel Remain in the steel Degrade mechanical properties Degrade mechanical properties Cause problem in casting Cause problem in casting 6

7 Inclusion Modification Calcium Treatment Calcium Treatment Adding calcium Adding calcium –Lowered melting point –Enhanced castability 7

8 CaO-Al2O3 binary system 8 P.C. Pistorious, R.J. Fruehan, 2009

9 Mass Transfer steps in steelmaking bath Assumption of equilibrium at the interface Assumption of equilibrium at the interface 1-Transfer of reactants from the metal phase to the slag/metal interface 1-Transfer of reactants from the metal phase to the slag/metal interface 2-Chemical reaction at the slag-metal interface (very fast in steelmaking T) 2-Chemical reaction at the slag-metal interface (very fast in steelmaking T) 3-Transfer of products away from the slag metal interface 3-Transfer of products away from the slag metal interface 9

10 Mass Transfer Metal- Inclusion Initial alumina Initial aluminainclusion content and size content and size levels of Sulfur levels of Sulfur levels of Oxygen levels of Oxygen Calcium feed rates Calcium feed rates Presence of multiple pumping source of dissolving element as in MgO.Al2O3 spinels Presence of multiple pumping source of dissolving element as in MgO.Al2O3 spinels 10

11 11 Spinels!! (shsh….it’s a bad word!) (shsh….it’s a bad word!)

12 Al 2 O 3.MgO Spinel inclusions Al 2 O 3.MgO Spinel inclusions 12

13 Possible sources of dissolved Mg to form Spinels: Possible sources of dissolved Mg to form Spinels: 13 Refractory Alloying additions Top slag

14 14

15 Change in composition slag during processing of steel 15 Proces Time

16 Multi-Component Reaction Model Work based on the model of Robertson et al. (1984) Work based on the model of Robertson et al. (1984) Local equilibrium assumed at the slag- metal interface Local equilibrium assumed at the slag- metal interface Generalized equilibrium reaction can be stated as: Generalized equilibrium reaction can be stated as:where: Metal Slag [Mn] [O] (MnO) 16

17 System represented by series of differential equations: System represented by series of differential equations: Reaction are coupled using flux density equations: Reaction are coupled using flux density equations: Newton-Raphson subroutine used to solve overall oxygen balance Newton-Raphson subroutine used to solve overall oxygen balance Interfacial concentrations were determined and trajectories updated Interfacial concentrations were determined and trajectories updated Kinetic Model Formulation Metal: Slag: Robertson, D.G.C., Deo, B., and Ohguchi, S., 1984, Ironmaking and Steemaking, Vol. 11, No. 1, pp

18 Effect of slag(FeO+ MnO) content on average inclusion content Kevin Graham, Thesis,

19 Effect of Top Slag on Mg Content of Steel Kevin Graham, Thesis,

20 Does top slag impact Ca Content of steel too? 20

21 Representative study plot for heat processed in LMF2 21

22 Example of results, sample S1 and M1 22

23 Example of Results samples M2 23

24 Sample M3 24

25 Sample M4 MgO+CaO+L SP L MgO+L SP+L S Sample M4 25

26 Process Conditions and Inclusions Chemistry 26

27 there seems to be a close relationship between the Max MgO as seen in M3 of heats with the amount Sulfur decreased from its initial value to the value it reached in M3 there seems to be a close relationship between the Max MgO as seen in M3 of heats with the amount Sulfur decreased from its initial value to the value it reached in M3 27 Heat # dS up to M3 Max % MgO inc

28 Summary Kinetics of inclusions transformations are controlled by mass transfer in metal Kinetics of inclusions transformations are controlled by mass transfer in metal Composition of both metal and slag changes during the processing which can be described by the multi-component kinetic model Composition of both metal and slag changes during the processing which can be described by the multi-component kinetic model There is a strong relation between the chemical composition of slag and the injection of Mg in the metal and forming spinel inclusions There is a strong relation between the chemical composition of slag and the injection of Mg in the metal and forming spinel inclusions There can be a link between the conditioning of slag specially for desulfurization and increase of MgO level in steel There can be a link between the conditioning of slag specially for desulfurization and increase of MgO level in steel 28

29 Continuing the study on impact of industrial process parameters Continuing the study on impact of industrial process parameters –Slag carryover from EAF –Slag conditioning –Additions Composition Composition Time of addition Time of addition Impact of initial size and distribution of inclusions Impact of initial size and distribution of inclusions Kinetics of oxygen removal, measurements of total oxygen Kinetics of oxygen removal, measurements of total oxygen Investigation of the impact of refractory and other possible sources of Mg to form spinel inclusions Investigation of the impact of refractory and other possible sources of Mg to form spinel inclusions Calcium is injected as wire into the steel, and the rates of dissolution need to be determined. Calcium is injected as wire into the steel, and the rates of dissolution need to be determined. Completion of the model Completion of the model Validation with the experimental data Validation with the experimental data 29 Future Work

30 Acknowledgements My Supervisor Dr. Gordon Irons My Supervisor Dr. Gordon Irons Dr. Ken Coley and Dr. Chris Swartz Dr. Ken Coley and Dr. Chris Swartz Steel Research Centre, John Thompson Steel Research Centre, John Thompson Arcelor Mittal Dofasco Team, Don Holdridge, Steve Waterfalls, Dongsheng Liao Arcelor Mittal Dofasco Team, Don Holdridge, Steve Waterfalls, Dongsheng Liao My sister, Shideh Fathi My sister, Shideh Fathi All of you, my friends in MSE All of you, my friends in MSE 30

31 31 PEACE


Download ppt "Study of kinetics of Inclusions Transformations in Ladle Metallurgical Furnace for the Production of LCAK Steels Departmental Seminar Presentation Mahshid."

Similar presentations


Ads by Google