The paper presents results of bath behaviour in the ladle model investigation during its gas argon bubbling realised
by one or two stir elements situated in the ladle bottom. The study was performed with use of physical
modelling method on a scale model 1 to 10. Development of homogenisation processes after start of bubbling
was evaluated on the basis of electrical conductivity and temperature change, which were measured at three
points of the ladle volume by conductivity and temperature sensors. Executed works were realised for conditions
of 180 tons steel ladles.Fizikalno modeliranje skrućivanja taline u loncu s argonskim miješanjem. Članak rad prikazuje rezultate
eksperimentalnog istraživanja ponašanja taline u modelu lonca s miješanjem pomoću mjehurića argona
dovedenog kroz jedan ili dva mješača na dnu lonca. Istraživanje je provedeno koristeći metodu fizikalnog modeliranja
na modelu u mjerilu 1 : 10. Tijek skrućivanja (homogenizacije) nakon početka upuštanja mjehurića
procjenjivan je temeljem promjena električne vodljivosti i temperature, mjerenjima pomoću senzora vodljivosti
i temeprature na tri točke unutar volumena lonca. Eksperiment je proveden za uvjete lonca od 180 tona

Gryc, Karel

Michalek, Karel

Morávka, Jan

DSpace at VSB Technical University of Ostrava

K. MICHALEK, K. GRYC, J. MORÁVKAPHYSICAL MODELLING OF BATHHOMOGENISATION IN ARGON STIRRED LADLEReceived – Prispjelo: 2008-02-08Accepted – Prihva}eno: 2008-10-20Original Scientific Paper – Izvorni znanstveni radINTRODUCTIONBlowing of inert gas (usually argon) into the moltensteel in the ladle is the most available and sometimes ad-equate secondary steelmaking method for its chemicaland temperature homogeneity, which is carried out dur-ing and after the metallurgical operations such as alloy-ing, heating steel, chemical composition correction, etc.Homogenisation processes during argon bubblinginto steel in a ladle was investigated by many authors1-5 and it brought numerous partial pieces of knowl-edge. Some of them are already generally accepted andare used in daily practice almost in every steelmakingshop. With some simplification it can be summarisedthat for the given geometry of pouring ladle there existscertain optimum axle offset of the stir element, whichensures the best results from the viewpoint of ho-mogenisation time and rate, and last but not least itmakes also possible to optimise the influence of second-ary metallurgy processes on final liquid steel quality 6,7. In certain cases, it is possible to use bubbling throughtwo stir elements too.Usually, it is recommended to place the stirring ele-ment in the mid to two-thirds of the radius of the ladlebottom (from the centre of the ladle). This position,however, may not be optimal according to the previousdata obtained from physical modelling in terms of inten-sification of transmission phenomena between the slagand metal, such as in case of refining by synthetic slag.INVESTIGATED VARIANTS ANDUSED EXPERIMENTAL METHODOLOGIESExecuted works were realised for conditions of 180tons steel ladles. Physically modelled experiments wereaimed to obtain data about influence of argon volumet-ric flow rate and position of the stir element (SE) in theladle bottom on progress of homogenisation in the ladle.The second stage was focused on evaluation of simulta-neous bubbling through two stir elements in the ladlebottom in order to propose the optimum position of thesecond SE in the ladle bottom.Simultaneous bubbling is used mostly in large vol-ume ladles with higher D/H ratio (ladle diameter andheight). The main effect obtained by bubbling throughtwo SE in these ladles consists in quicker progress of ho-mogenisation, both of concentration and temperature,and minimisation or elimination of possible dead areasin steel bath volume, where melt movement stagnatesMETALURGIJA 48 (2009) 4, 215-218 215The paper presents results of bath behaviour in the ladle model investigation during its gas argon bubbling rea-lised by one or two stir elements situated in the ladle bottom. The study was performed with use of physicalmodelling method on a scale model 1 to 10. Development of homogenisation processes after start of bubblingwas evaluated on the basis of electrical conductivity and temperature change, which were measured at threepoints of the ladle volume by conductivity and temperature sensors. Executed works were realised for condi-tions of 180 tons steel ladles.Key words: steel, ladles, gas argon bubbling, stir elements, physical modellingFizikalnomodeliranje skru}ivanja taline u loncu s argonskimmije{anjem. ^lanak rad prikazuje rezul-tate eksperimentalnog istra`ivanja pona{anja taline u modelu lonca s mije{anjem pomo}u mjehuri}a argonadovedenog kroz jedan ili dva mje{a~a na dnu lonca. Istra`ivanje je provedeno koriste}i metodu fizikalnog mo-deliranja na modelu u mjerilu 1 : 10. Tijek skru}ivanja (homogenizacije) nakon po~etka upu{tanja mjehuri}aprocjenjivan je temeljem promjena elektri~ne vodljivosti i temperature, mjerenjima pomo}u senzora vodljivostii temeprature na tri to~ke unutar volumena lonca. Eksperiment je proveden za uvjete lonca od 180 tona.Klju~ne rije~i: ~elik, lonac, argonski mjehuri}i, mje{a~i, fizikalno modeliranje.ISSN 0543-5846METABK 48(4) 215-218 (2009)UDC-UDK 669.18:621.746.32:542.63:621.22.015.5:519.651=111K. Michalek, K. Gryc, Faculty of Metallurgy and Materials Engineering,V[B-TU Ostrava, Czech RepublicJ. Morávka, Material & Metallurgical Research Ltd., Ostrava, Czech Re-publicDSpace VŠB-TUO http://hdl.handle.net/10084/76055 18/06/2012with all detrimental consequences for bath homogene-ity. Another advantage of two SE lies in the fact that incase of failure of any one SE it is still possible to con-tinue bubbling through the other functional SE. TheFigure1 shows investigated positions of stir elements.Determination of physical similarity conditions wasbased on verified and used procedure published in ourown previous works, e.g. in 8, 9.While studying homogenisation processes occurringin the steel ladles blowing by argon is the chemicalinhomogeneity degree of homogenized compound con-tent in any place "A" and the time expressed by the dimensionless quantityCc ccE,A,E,A, E,HE,H, (1)where:cE,A, - mass concentration of the compound E in thebath at point A in time ,cE,H - mass concentration of the compound Ecorresponding to fully homogenised bath.The value of CE,A, quantity is a function of the set ofKi,j determining criteria and the parameters XA, YA, ZAdetermining the position of the "A" point in the bathC K X X Xi j A B CE,A,  ( ; ; ; ), , (2)This paper does not describe the detailed method toderive Ki,j criteria and their survey, however, this is al-ready contained in the previously cited works 8 - 10.Ladle model in length scale ML = 1:10 was used forexperimental model research. Argon flow rate measure-ment was realised by precise mass flowmeter with auto-matic regulation. Scale factor of volumetric flow rateMQv = 0,00576 was determined from the modifiedFroude’s criterion, which respects also influence ofblown argon expansion due to increase of its tempera-ture caused by passage through a liquid phase. Volumet-ric flow rate of argon in the model Qv´ = 1,4 l/min thencorresponds to the argon flow rate of basic operationalcase Qv = 243 l/min. Time scale factor was calculated tobe M = 0,3162. Argon bubbling in the model was real-ised by stir element design, which was a model equiva-lent of the real element for industrial conditions.Development of homogenisation processes afterstart of bubbling was evaluated on the basis of electricalconductivity and temperature change, which were mea-sured at three points of the ladle volume by conductivityand temperature sensors.Typical record of homogenisation process and therecord of the tracer change measured in three areas ofthe bath in the ladle model is shown in the Figure 2.The two types of visualisation methods were used forfluid flow pattern qualitative study. The first visualisa-tion method was based on injection of violet contrastsubstance (KMnO4) – see Figure 3.216 METALURGIJA 48 (2009) 4, 215-218K. MICHALEK et al.: PHYSICAL MODELLING OF BATH HOMOGENISATION IN ARGON STIRRED LADLEFigure 1. Positions of stir plugs in ladle bottom used formodelling studyFigure 2. Typical record of tracer concentration change inthree measured places of the bath in the ladlemodel after start of argon blowing through stirplugsFigure 3. Red tracer visualisation (KMnO4) of homogeni-sation processDSpace VŠB-TUO http://hdl.handle.net/10084/76055 18/06/2012In the case of the second visualisation method, the socalled light knife generated by the system of power lightsource was used for long exposition time photograph ofmoving reflection tracers (Figure 4).OBTAINED RESULTSUsing of one stir elementThe basic idea of the homogenised processes patternusing one stirring element in the position "A" can be ob-tained from the Figure 5.For purposes of industrial interpretation, the homo-geneity times measured on the model were re-calculatedwith use of already determined volumetric flow rate andtime scale factors (MQv, M) to industrial conditions ofthe above mentioned 180 tons steel ladles. These valueswere processed graphically and interlaid by regressionfunction of the type H = a × Qvb – see the Figure 6.The graph shows visible decrease of homogenisationtime values H with increase of argon volumetric flowrate. This decrease is not too significant and homogeni-sation time values vary between 100 to 150 s in the areaabove 400 l/min. Contrary to that, the homogenisationtime values steeply increase and they achieve up to 350 sin dependence on position of the SE in the flow rate areabelow 100 l/min and especially 50 l/min.From the viewpoint of homogenisation times, thecourse of curves also indicates that there are no distinctdifferences between bubbling through SE at positionsA, B and E. The position A (and possibly C, D) can beregarded as the most favourable position of the SE, be-cause it had somewhat shorter homogenisation times(approx. by 10 to 15 %) in comparison with the positionsB and E.Use of two stir elementsPhysical modelling was then used for investigationof stir elements combinations AB, AC, AD and AE.Physical modelling results are summarised in the Figure7.Combinations AB and AC are practically identicalfrom the viewpoint of the obtained homogeneity times.The combination AE is less favourable, as it had longerMETALURGIJA 48 (2009) 4, 215-218 217K. MICHALEK et al.: PHYSICAL MODELLING OF BATH HOMOGENISATION IN ARGON STIRRED LADLEFigure 4. The long exposition time photograph from thereflex tracer visualisationFigure 5. Behaviour of concentration and density bath in-homogeneity in ladle model after start of blo-wing at times of 15 and 40 s - volumetric flowQv´ = 0,34 l/min (Qv = 59 l/min)Figure 6. Influence of argon volumetric flow rate Qv onthe achieved homogenisation times tH for threepositions of stir elements in the ladle bottommarked A, B and E. The table contains obtainedregression functions and their determination co-efficients for individually modelled variantsA : y = 2557,7 x-0,5168R2 = 0,9662B : y = 2647,8 x-0,5085R2 = 0,9698E : y = 2773,1 x-0,5122R2 = 0,99DSpace VŠB-TUO http://hdl.handle.net/10084/76055 18/06/2012homogenisation times than variants AB and AC. Sur-prisingly the worst was the variant AD, in which loca-tion of the SE in position D where the y axis was axiallysymmetrical to the position A. This combination had thelongest homogenisation times in full volumetric flowsrange. It represents increase of time by 30 to 40 % incomparison with combinations AB or AC.Explanation of this apparent anomaly can be foundin flow character or in formation of two recirculationzones in the pouring ladle, directions of which are oppo-site to each other. In this way, the speed components offlowing mutually significantly influence or even elimi-nate each other with negative impact on components andheat transfer. Homogenisation process, both of concen-tration and temperature, slows down, and obtaining ofhomogenous stabilised bath requires longer bubblingand thus bigger blown argon volume, which can causeeven greater drop in temperature.CONCLUSIONPhysical modelling method was used for model in-vestigation of influence of argon bubbling through a stirelement or two stir elements situated in the ladle bottomin the course of homogenisation processes in a bath. Thebest results were obtained in variants with simultaneousbubbling through the SE in positions A and B or A and C(Figure 7). On the other hand, the longest homogenisa-tion times were obtained in the simultaneous bubblingvariant with location of the SE in positions A and D,which can be explained by creation of two re-circulationzones in pouring ladle with important mutual influenc-ing and elimination of components transfer rate.In the second part of the described model study (seethe paper “Mathematical Identification of Bath Ho-mogenisation in Argon Stirred Ladle“), the results of ex-perimental investigation were processed by mathemati-cal models.The work was realised within the frame of solution ofthe grant project No.106/07/0407 under financial sup-port of the Czech Science Foundation.REFERENCES1 ¼. Dor~ák, J. Terpák, Metalurgija 45 (2006) 2, 93-96.2 J.P. Rogler, L.J. Heaslip, D. Xu, M. Mehrvar, AIST Tran-sactions (2004) April, 81-93.3 M. Madan, D. Satish, D. Mazumdar, ISIJ International 45(2005) 5, 677-685.4 M.A. Ramírez-Argáez, H. Nava-Ramos, Proceedings, 15thInternational Metallurgical and Material ConferenceMETAL, 2006, Hradec nad Moravicí, Czech Republic,1-11.5 M. Zhu, S. Zheng, Z. Huang, W. Gu, Steel Research Int. 76(2005), 10, 718-722.6 J. Krajcar, Metalurgija 32 (1993) 3, 87-92.7 V. Ferketi}, J. Krajcar, A. Ivan~an, Metalurgija 35 (1996) 1,43-48.8 M. Benda, K. Michalek, Hutnické listy (1987) 6, 402-411.9 M. Benda, K. Michalek et al. Hutnické listy (1989) 5,314-320.Note: The responsible translator for English language is B. [kandera,Czech Republic.218 METALURGIJA 48 (2009) 4, 215-218K. MICHALEK et al.: PHYSICAL MODELLING OF BATH HOMOGENISATION IN ARGON STIRRED LADLEFigure 7. Influence of argon volumetric flow rate Qv on theachieved homogenisation times tH for four com-binations of stir elements position marked AB,AC, AD and AE. The table contains the obtainedregression functions and their determination co-efficients for individually modelled variantsAB : y = 4381,4 x-0,5971R2 = 0,9666AC : y = 4966,9 x-0,6245R2 = 0,989AD : y = 7223,5 x-0,6437R2 = 0,9284AE : y = 5251,6 x-0,6115R2 = 0,9857DSpace VŠB-TUO http://hdl.handle.net/10084/76055 18/06/2012

Fizikalno modeliranje skrućivanja taline u loncu s argonskim miješanjem

The paper presents results of bath behaviour in the ladle model investigation during its gas argon bubbling realised by one or two stir elements situated in the ladle bottom. The study was performed with use of physical modelling method on a scale model 1 to 10. Development of homogenisation processes after start of bubbling was evaluated on the basis of electrical conductivity and temperature change, which were measured at three points of the ladle volume by conductivity and temperature sensors. Executed works were realised for conditions of 180 tons steel ladles.Članak rad prikazuje rezultate eksperimentalnog istraživanja ponašanja taline u modelu lonca s miješanjem pomoću mjehurića argona dovedenog kroz jedan ili dva mješača na dnu lonca. Istraživanje je provedeno koristeći metodu fizikalnog modeliranja na modelu u mjerilu 1 : 10. Tijek skrućivanja (homogenizacije) nakon početka upuštanja mjehurića procjenjivan je temeljem promjena električne vodljivosti i temperature, mjerenjima pomoću senzora vodljivosti i temeprature na tri točke unutar volumena lonca. Eksperiment je proveden za uvjete lonca od 180 tona

K. Michalek

K. Gryc

J. Morávka

Hrčak - Portal of scientific journals of Croatia

K. MICHALEK, K. GRYC, J. MORÁVKAPHYSICAL MODELLING OF BATHHOMOGENISATION IN ARGON STIRRED LADLEReceived – Prispjelo: 2008-02-08Accepted – Prihva}eno: 2008-10-20Original Scientific Paper – Izvorni znanstveni radINTRODUCTIONBlowing of inert gas (usually argon) into the moltensteel in the ladle is the most available and sometimes ad-equate secondary steelmaking method for its chemicaland temperature homogeneity, which is carried out dur-ing and after the metallurgical operations such as alloy-ing, heating steel, chemical composition correction, etc.Homogenisation processes during argon bubblinginto steel in a ladle was investigated by many authors1-5 and it brought numerous partial pieces of knowl-edge. Some of them are already generally accepted andare used in daily practice almost in every steelmakingshop. With some simplification it can be summarisedthat for the given geometry of pouring ladle there existscertain optimum axle offset of the stir element, whichensures the best results from the viewpoint of ho-mogenisation time and rate, and last but not least itmakes also possible to optimise the influence of second-ary metallurgy processes on final liquid steel quality 6,7. In certain cases, it is possible to use bubbling throughtwo stir elements too.Usually, it is recommended to place the stirring ele-ment in the mid to two-thirds of the radius of the ladlebottom (from the centre of the ladle). This position,however, may not be optimal according to the previousdata obtained from physical modelling in terms of inten-sification of transmission phenomena between the slagand metal, such as in case of refining by synthetic slag.INVESTIGATED VARIANTS ANDUSED EXPERIMENTAL METHODOLOGIESExecuted works were realised for conditions of 180tons steel ladles. Physically modelled experiments wereaimed to obtain data about influence of argon volumet-ric flow rate and position of the stir element (SE) in theladle bottom on progress of homogenisation in the ladle.The second stage was focused on evaluation of simulta-neous bubbling through two stir elements in the ladlebottom in order to propose the optimum position of thesecond SE in the ladle bottom.Simultaneous bubbling is used mostly in large vol-ume ladles with higher D/H ratio (ladle diameter andheight). The main effect obtained by bubbling throughtwo SE in these ladles consists in quicker progress of ho-mogenisation, both of concentration and temperature,and minimisation or elimination of possible dead areasin steel bath volume, where melt movement stagnatesMETALURGIJA 48 (2009) 4, 215-218 215The paper presents results of bath behaviour in the ladle model investigation during its gas argon bubbling rea-lised by one or two stir elements situated in the ladle bottom. The study was performed with use of physicalmodelling method on a scale model 1 to 10. Development of homogenisation processes after start of bubblingwas evaluated on the basis of electrical conductivity and temperature change, which were measured at threepoints of the ladle volume by conductivity and temperature sensors. Executed works were realised for condi-tions of 180 tons steel ladles.Key words: steel, ladles, gas argon bubbling, stir elements, physical modellingFizikalno modeliranje skru}ivanja taline u loncu s argonskim mije{anjem. ^lanak rad prikazuje rezul-tate eksperimentalnog istra`ivanja pona{anja taline u modelu lonca s mije{anjem pomo}u mjehuri}a argonadovedenog kroz jedan ili dva mje{a~a na dnu lonca. Istra`ivanje je provedeno koriste}i metodu fizikalnog mo-deliranja na modelu u mjerilu 1 : 10. Tijek skru}ivanja (homogenizacije) nakon po~etka upu{tanja mjehuri}aprocjenjivan je temeljem promjena elektri~ne vodljivosti i temperature, mjerenjima pomo}u senzora vodljivostii temeprature na tri to~ke unutar volumena lonca. Eksperiment je proveden za uvjete lonca od 180 tona.Klju~ne rije~i: ~elik, lonac, argonski mjehuri}i, mje{a~i, fizikalno modeliranje.ISSN 0543-5846METABK 48(4) 215-218 (2009)UDC-UDK 669.18:621.746.32:542.63:621.22.015.5:519.651=111K. Michalek, K. Gryc, Faculty of Metallurgy and Materials Engineering,V[B-TU Ostrava, Czech RepublicJ. Morávka, Material & Metallurgical Research Ltd., Ostrava, Czech Re-publicwith all detrimental consequences for bath homogene-ity. Another advantage of two SE lies in the fact that incase of failure of any one SE it is still possible to con-tinue bubbling through the other functional SE. TheFigure1 shows investigated positions of stir elements.Determination of physical similarity conditions wasbased on verified and used procedure published in ourown previous works, e.g. in 8, 9.While studying homogenisation processes occurringin the steel ladles blowing by argon is the chemicalinhomogeneity degree of homogenized compound con-tent in any place "A" and the time expressed by the dimensionless quantityCc ccE,A,E,A, E,HE,H, (1)where:cE,A, - mass concentration of the compound E in thebath at point A in time ,cE,H - mass concentration of the compound Ecorresponding to fully homogenised bath.The value of CE,A, quantity is a function of the set ofKi,j determining criteria and the parameters XA, YA, ZAdetermining the position of the "A" point in the bathC K X X Xi j A B CE,A,  ( ; ; ; ), , (2)This paper does not describe the detailed method toderive Ki,j criteria and their survey, however, this is al-ready contained in the previously cited works 8 - 10.Ladle model in length scale ML = 1:10 was used forexperimental model research. Argon flow rate measure-ment was realised by precise mass flowmeter with auto-matic regulation. Scale factor of volumetric flow rateMQv = 0,00576 was determined from the modifiedFroude’s criterion, which respects also influence ofblown argon expansion due to increase of its tempera-ture caused by passage through a liquid phase. Volumet-ric flow rate of argon in the model Qv´ = 1,4 l/min thencorresponds to the argon flow rate of basic operationalcase Qv = 243 l/min. Time scale factor was calculated tobe M = 0,3162. Argon bubbling in the model was real-ised by stir element design, which was a model equiva-lent of the real element for industrial conditions.Development of homogenisation processes afterstart of bubbling was evaluated on the basis of electricalconductivity and temperature change, which were mea-sured at three points of the ladle volume by conductivityand temperature sensors.Typical record of homogenisation process and therecord of the tracer change measured in three areas ofthe bath in the ladle model is shown in the Figure 2.The two types of visualisation methods were used forfluid flow pattern qualitative study. The first visualisa-tion method was based on injection of violet contrastsubstance (KMnO4) – see Figure 3.216 METALURGIJA 48 (2009) 4, 215-218K. MICHALEK et al.: PHYSICAL MODELLING OF BATH HOMOGENISATION IN ARGON STIRRED LADLEFigure 1. Positions of stir plugs in ladle bottom used formodelling studyFigure 2. Typical record of tracer concentration change inthree measured places of the bath in the ladlemodel after start of argon blowing through stirplugsFigure 3. Red tracer visualisation (KMnO4) of homogeni-sation processIn the case of the second visualisation method, the socalled light knife generated by the system of power lightsource was used for long exposition time photograph ofmoving reflection tracers (Figure 4).OBTAINED RESULTSUsing of one stir elementThe basic idea of the homogenised processes patternusing one stirring element in the position "A" can be ob-tained from the Figure 5.For purposes of industrial interpretation, the homo-geneity times measured on the model were re-calculatedwith use of already determined volumetric flow rate andtime scale factors (MQv, M) to industrial conditions ofthe above mentioned 180 tons steel ladles. These valueswere processed graphically and interlaid by regressionfunction of the type H = a × Qvb – see the Figure 6.The graph shows visible decrease of homogenisationtime values H with increase of argon volumetric flowrate. This decrease is not too significant and homogeni-sation time values vary between 100 to 150 s in the areaabove 400 l/min. Contrary to that, the homogenisationtime values steeply increase and they achieve up to 350 sin dependence on position of the SE in the flow rate areabelow 100 l/min and especially 50 l/min.From the viewpoint of homogenisation times, thecourse of curves also indicates that there are no distinctdifferences between bubbling through SE at positionsA, B and E. The position A (and possibly C, D) can beregarded as the most favourable position of the SE, be-cause it had somewhat shorter homogenisation times(approx. by 10 to 15 %) in comparison with the positionsB and E.Use of two stir elementsPhysical modelling was then used for investigationof stir elements combinations AB, AC, AD and AE.Physical modelling results are summarised in the Figure7.Combinations AB and AC are practically identicalfrom the viewpoint of the obtained homogeneity times.The combination AE is less favourable, as it had longerMETALURGIJA 48 (2009) 4, 215-218 217K. MICHALEK et al.: PHYSICAL MODELLING OF BATH HOMOGENISATION IN ARGON STIRRED LADLEFigure 4. The long exposition time photograph from thereflex tracer visualisationFigure 5. Behaviour of concentration and density bath in-homogeneity in ladle model after start of blo-wing at times of 15 and 40 s - volumetric flowQv´ = 0,34 l/min (Qv = 59 l/min)Figure 6. Influence of argon volumetric flow rate Qv onthe achieved homogenisation times tH for threepositions of stir elements in the ladle bottommarked A, B and E. The table contains obtainedregression functions and their determination co-efficients for individually modelled variantsA : y = 2557,7 x-0,5168R2 = 0,9662B : y = 2647,8 x-0,5085R2 = 0,9698E : y = 2773,1 x-0,5122R2 = 0,99homogenisation times than variants AB and AC. Sur-prisingly the worst was the variant AD, in which loca-tion of the SE in position D where the y axis was axiallysymmetrical to the position A. This combination had thelongest homogenisation times in full volumetric flowsrange. It represents increase of time by 30 to 40 % incomparison with combinations AB or AC.Explanation of this apparent anomaly can be foundin flow character or in formation of two recirculationzones in the pouring ladle, directions of which are oppo-site to each other. In this way, the speed components offlowing mutually significantly influence or even elimi-nate each other with negative impact on components andheat transfer. Homogenisation process, both of concen-tration and temperature, slows down, and obtaining ofhomogenous stabilised bath requires longer bubblingand thus bigger blown argon volume, which can causeeven greater drop in temperature.CONCLUSIONPhysical modelling method was used for model in-vestigation of influence of argon bubbling through a stirelement or two stir elements situated in the ladle bottomin the course of homogenisation processes in a bath. Thebest results were obtained in variants with simultaneousbubbling through the SE in positions A and B or A and C(Figure 7). On the other hand, the longest homogenisa-tion times were obtained in the simultaneous bubblingvariant with location of the SE in positions A and D,which can be explained by creation of two re-circulationzones in pouring ladle with important mutual influenc-ing and elimination of components transfer rate.In the second part of the described model study (seethe paper “Mathematical Identification of Bath Ho-mogenisation in Argon Stirred Ladle“), the results of ex-perimental investigation were processed by mathemati-cal models.The work was realised within the frame of solution ofthe grant project No.106/07/0407 under financial sup-port of the Czech Science Foundation.REFERENCES1 ¼. Dor~ák, J. Terpák, Metalurgija 45 (2006) 2, 93-96.2 J.P. Rogler, L.J. Heaslip, D. Xu, M. Mehrvar, AIST Tran-sactions (2004) April, 81-93.3 M. Madan, D. Satish, D. Mazumdar, ISIJ International 45(2005) 5, 677-685.4 M.A. Ramírez-Argáez, H. Nava-Ramos, Proceedings, 15thInternational Metallurgical and Material ConferenceMETAL, 2006, Hradec nad Moravicí, Czech Republic,1-11.5 M. Zhu, S. Zheng, Z. Huang, W. Gu, Steel Research Int. 76(2005), 10, 718-722.6 J. Krajcar, Metalurgija 32 (1993) 3, 87-92.7 V. Ferketi}, J. Krajcar, A. Ivan~an, Metalurgija 35 (1996) 1,43-48.8 M. Benda, K. Michalek, Hutnické listy (1987) 6, 402-411.9 M. Benda, K. Michalek et al. Hutnické listy (1989) 5,314-320.Note: The responsible translator for English language is B. [kandera,Czech Republic.218 METALURGIJA 48 (2009) 4, 215-218K. MICHALEK et al.: PHYSICAL MODELLING OF BATH HOMOGENISATION IN ARGON STIRRED LADLEFigure 7. Influence of argon volumetric flow rate Qv on theachieved homogenisation times tH for four com-binations of stir elements position marked AB,AC, AD and AE. The table contains the obtainedregression functions and their determination co-efficients for individually modelled variantsAB : y = 4381,4 x-0,5971R2 = 0,9666AC : y = 4966,9 x-0,6245R2 = 0,989AD : y = 7223,5 x-0,6437R2 = 0,9284AE : y = 5251,6 x-0,6115R2 = 0,9857

English

http://dspace.vsb.cz/bitstream/10084/76055/2/MET_48_4_215_218_Michalek.pdf

Fizikalno modeliranje skrućivanja taline u loncu s argonskim miješanjem

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