News by year
Journal paper on mathematical modelling of the CAS-OB process
A mathematical model for the reduction stage of the CAS-OB process has been published in the December issue of Metallurgical and Materials Transactions B. Metallurgical and Materials Transactions B is a joint peer-reviewed journal of ASM International and the Minerals, Metals & Materials Society (USA). The kinetic description of the model is based on the assumption that reactions take place primarily between emulsified slag droplets and metal bath. The model accounts for the relevant heat and mass transfer resistances in the system, and thus enables detailed studies on the rate-limiting mechanisms in the CAS-OB process.
P. Sulasalmi, V.-V. Visuri, A. Kärnä, M. Järvinen, S. Ollila, and T. Fabritius, "A Mathematical Model for the Reduction Stage of the CAS-OB Process", Metallurgical and Materials Transactions B, vol. 47, no. 6, pp. 3544–3556, 2016.
P. Sulasalmi's doctoral thesis published
The doctoral thesis of my colleague Mr. Petri Sulasalmi, entitled "Modelling of Slag Emulsification and Slag Reduction in CAS-OB Process", was examined successfully on December 2, 2016 at University of Oulu. The thesis is available here. The thesis includes three joint publications, which are available here, here and here
Column on doctoral studies
A column titled "Jatkoajalla" was published in the November issue of Oulun ylioppilaslehti. The column discusses the challenges and recent changes in the doctoral training at University of Oulu, and highlights the need for more standardised structures.
V.-V. Visuri, "Jatkoajalla", Oulun ylioppilaslehti, vol. 56, no. 6, pp. 24, 2016.
Travel grant for the ESTAD2017 conference
A travel grant was awarded by the Technology Industries of Finland Centennial Foundation for participating in the European Steel Technology and Application Days 2017 (ESTAD 2017) conference to be held at Vienna, Austria in June 2017.
Three posters at the DIMECC 9th Annual Seminar
Three poster presentations were held at the DIMECC 9th Annual Seminar in Helsinki, Finland. The first poster, titled "Vibration-based assessment of gas-stirring efficiency in ladle treatments", presents two new indices for following the gas-stirring efficiency and condition of the ladle.
The second poster is entitled "Simulators for the AOD and CAS-OB processes", and presents the latest development steps and functionalities of the mathematical simulators for AOD and CAS-OB processes. Furthermore, the economic potential of the simulators is illustrated with an actual example regarding the AOD process.
The third poster, entitled "Hot metal desulphurisation simulator" illustrates the modelling approach of a new mathematical model, which focuses on the kinetics of desulphurisation. The model enables rapid testing of different desulphurisation reagents and practices.
Instructed: Master's thesis on the use of AOD models for process development
A Master's thesis written by V. Kivelä and instructed by V.-V. Visuri and T. Fabritius has been published. The objective of the thesis was to find faster and more effective decarburization practices for the studied steel grades.
Journal paper on mathematical modelling of parallel mass transfer limited reactions
A law of mass action (LMA) based kinetic approach for modelling of parallel mass transfer limited reactions has been published in the September issue of ISIJ International. ISIJ International is a peer-reviewed journal of the Iron and Steel Institute of Japan. The mathematical proof and potential applications of the proposed method are discussed in detail.
M. Järvinen, V.-V. Visuri, E.-P. Heikkinen, A. Kärnä, P. Sulasalmi, C. De Blasio, and T. Fabritius, "Law of Mass Action Based Kinetic Approach for the Modelling of Parallel Mass Transfer Limited Reactions: Application to Metallurgical Systems", ISIJ International, vol. 56, no. 9, pp. 1543–1552, 2016.
Instructed: Bachelor's thesis on temperature measurement of molten ferrochrome
The Bachelor's thesis of A.-M. Heikka was fininished in August 2016. The thesis was instructed by V.-V. Visuri and its aim was to study the the changes in the temperature of the molten ferrochrome. The results suggest that the temperature of the slag on top of the metal bath is higher than that of the metal bath. The temperature change during tapping was found to be miniscule.
Visiting the 5th International Conference on Process Development in Iron and Steelmaking
Two papers were published in the Proceedings of the 5th International Conference on Process Development in Iron and Steelmaking (SCANMET V) held in Luleå, Sweden. The first paper, titled "A Physical Modelling Study on Mixing in the AOD Process", presents the results regarding the effect of gas injection and position of the pH measurement on the mixing time.
The second paper, entitled "Vibration-based Assessment of Gas Stirring Intensity in Ladle Treatments", presents the preliminary results obtained from a test campaign consisting of roughly 300 heats from a vacuum tank degassing unit operated by SSAB Europe in Raahe, Finland. It is proposed that vibration measurements are a promising method for condition monitoring of ladles.
V.-V. Visuri, E. Isohookana, A. Kärnä, T. Haas, R. H. Eriç, and T. Fabritius, ”A Physical Modelling Study of Mixing in an AOD Vessel”, Proceedings of the 5th International Conference on Process Development in Iron and Steelmaking, Swerea MEFOS, Luleå, Sweden, no. 88, 2016.
M. Pylvänäinen, V.-V. Visuri, T. Liedes, J. Laurila, K. Karioja, S. Pikkupeura, S. Ollila, and T. Fabritius, ”Vibration-based Assessment of Gas Stirring Intensity in Ladle Treatments”, Proceedings of the 5th International Conference on Process Development in Iron and Steelmaking, Swerea MEFOS, Luleå, Sweden, no. 14, 2016.
MIMESIS project meeting at Weierstrass Institute for Applied Analysis and Stochastics in Berlin
The first project meeting of the MIMESIS project was held from June 8 to June 10, 2017 in Berlin, Germany. The meeting was hosted by Weierstrass Institute for Applied Analysis and Stochastics (WIAS). The project is scheduled to run from January 2016 to December 2018.
Instructed: Master's thesis on alloying the the BOF process
A Master's thesis written by M. Prokkola and instructed by V.-V. Visuri and D. Porter has been published. The objective of the thesis was to develop a new offline model for more cost-effective alloying in the BOF process.
Conference paper on physical modelling of the effect of top-blowing and slag on mixing in the AOD process
A conference article entitled "Physical Modelling of the Effect of Slag and Top-Blowing on Mixing in the AOD Process” was published in the Proceedings of the Tenth International Conference on Molten Slags, Fluxes, and Salts (Molten16) held in Seattle, WA, USA. The results of the study suggest that both top-blowing and top slag have an adverse effect on the efficiency of bath mixing, though this effect was found to decrease when the intensity of side-blowing was increased.
T. Haas, V.-V. Visuri, A. Kärnä, E. Isohookana, P. Sulasalmi, R. H. Eriç, H. Pfeifer, and T. Fabritius, "Physical Modelling of the Effect of Slag and Top-Blowing on Mixing in the AOD Process", in R. G. Reddy, P. Chaubal, P. C. Pistorius and U. Pal (eds.), Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes, and Salts, The Minerals, Metals and Materials Society, Seattle, WA, USA, pp. 999–1008, 2016.
Instructed: Master's thesis on electrochemical measurement of silicon from ferroalloys
MAY 5, 2016
A Master's thesis written by H. Pesonen and instructed by V.-V. Visuri and T. Fabritius has been published. The aim of the thesis was to study the use of electrochemical measurement for rapid determination of silicon content in molten ferrochrome and processes ferrochrome melts.
Grant for doctoral studies
An encouragement grant was awarded by Tauno Tönning Foundation for the doctoral thesis work on rate phenomena in the AOD process. The support of the foundation is gratefully acknowledged.
Presentation on rate phenomena in the AOD process
An invited presentation, entitled "Rate phenomena in the AOD process", was held in the Jernkontoret seminar "Thermodynamical calculations as support for control, development and understanding of pyro metallurgical processes" held at Stockholm, Sweden. The presentation discussed the macro- and microkinetic aspects of AOD refining along with examples from recent research at Process Metallurgy Research Unit.
Technical report on SIMP SC 2.1 DYNAMO
Dynamic multiphysics modelling as guidance in progressing steel making (DYNAMO) is part of the SIMP programme coordinated by DIMECC Oy. A description of the main objectives and research methods of the DYNAMO project was published in the February issue of Materia (vol. 74, no. 1, pp. 46).
M. Leinonen, V.-V. Visuri, and I. Baarman, “Dynamic multiphysics modelling as guidance in progressing steel making (DYNAMO)”, Materia, vol. 74, no. 1, pp. 46.
Journal paper on reactivity of limestone and dolomite in acidic environment
A paper on employing a step-wise titration method under semi-slow reaction regime for evaluating the reactivity of limestone and dolomite in acidic environment was published in the February issue of Minerals Engineering. Minerals Engineering is a peer-reviewed journal published by Elsevier. The studied limestone and dolomite samples had different formation periods and geological backgrounds. A parametric evaluation for the reaction rate was performed at each titration step using an implemented software procedure. The experimental data were fitted to the model.
C. De Blasio, C. Carletti, A. Lundell, V.-V. Visuri, T. Kokkonen, T. Westerlund, T. Fabritius, and M. Järvinen, ``Employing a step-wise titration method under semi-slow reaction regime for evaluating the reactivity of limestone and dolomite in acidic environment", Minerals Engineering, vol. 86, no. 2, pp. 43–58, 2016.