Inclusion interactions during flotation in liquid metals

• Applicants: Dr.-Ing. Sven Eckert; Professor Dr.-Ing. Jochen Fröhlich
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials ; Fluid Mechanics
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 284002692

• Final Report Year: 2022

Final Report Abstract

Inclusion cleanliness is a major challenge, since it strongly influences the mechanical performance of metallic alloys, and can reduce the weight of metallic parts. Although aggregation is the dominating mechanism influencing the population of inclusions the phenomenon is still not fully understood, nor adequately captured by correlations. This lack of knowledge results from the complexity of experiments with liquid metals, as well as from the multi-scale nature of the problem which makes it impossible for state-of-the-art simulations to capture all the physics at once. FLOTINC addressed these two bottlenecks. Original experiments with low melting point liquid metals were built for investigating the aggregation of oxid particles in shear flow and their dynamic behaviour in bubbly flow. In parallel, direct numerical simulations were developed for studying hydrodynamic efficiency of aggregation at the inclusion scale and inclusion dynamics at the bubble scale, with a single bubble as well as bubble swarms. In the project, significant scientific steps forward were accomplished during the four years the project was effectively run. Among them: • An experimental procedure previously not available was developed for wetting oxide particles into liquid metal. • The Hydrodynamic efficiency of the aggregation kernel was obtained numerically now filling a gap in the scientific literature, particularly for the Reynolds number range of interest for inclusions in bubbly flow; • Direct numerical simulations of bubble swarms and inclusions were conducted together with collision detection, which had not been done before in the literature. • The Collision frequency of inclusions in turbulent bubble-driven flow was determined under the conditions of a bubble-stirred ladle, identifying low collision rates as bottle neck. • An original X-ray imaging in low melting point liquid metal was used to provide unique insight into rising bubbles and sedimenting particles which were tracked separately. • Neutron imaging revealed the flow field up- and downstream the cylindrical obstacle. The FLOTINC project established close collaborations between the French and the German laboratories. A clear wish to pursue the collaboration was expressed during the final workshop, motivated by the interest seen in the discussions, as experienced also at other conferences where the results of FLOTINC were presented. The results of FLOTINC, the successful collaboration, and the lack of data and methods in industry prove the need for more research on this topic. The FLOTINC partners are presently investigating how this could be realized. Surprise findings: Wetting of particles in liquid metal is extremely difficult. Fortunately, the issue could be solved in the project with an original procedure. - Neutron imaging appears to be a very promising technique for particle tracking in liquid metals.

Publications

• Impact of particle boundary conditions on the collision rates of inclusions around a single bubble rising in liquid metal, Proc. Appl. Math. Mech., 18:e201800029, 2018
  R. May, F. Gruy, J. Fröhlich
  
• Finite-Reynolds hydrodynamic interactions between particles in a shear flow: impact on cross section and collision efficiency, 10th Int. Conf. Multiphase Flow, ICMF 2019, Rio de Janeiro, Brazil, 2019
  M. Gisselbrecht, J.-S. Kroll-Rabotin, J.P. Bellot, B. Ott, J. Fröhlich
  
• Tracking of particles in froth using neutron imaging, Chemie Ingenieur Technik, 91(7):1001–1007, 2019
  S. Heitkam, T. Lappan, S. Eckert, P. Trtik, K. Eckert
  
• Multiscale simulation of non-metallic inclusion aggregation in a fully resolved bubble swarm in liquid steel, Metals, 10(4):517, 2020
  J.-S. Kroll-Rabotin, M. Gisselbrecht, B. Ott, R. May, J. Fröhlich, J.-P. Bellot
  
• Neutron radiography of particle-laden liquid metal flow driven by an electromagnetic induction pump. Magnetohydrodynamics, 56(2/3):167–76, 2020
  T. Lappan, M. Sarma, S. Heitkam, P. Trtik, D. Mannes, K. Eckert, S. Eckert
  
• X-ray particle tracking velocimetry in liquid foam flow. Soft Matter, 16(8):2093–2103, 2020
  T. Lappan, A. Franz, H. Schwab, U. Kühn, S. Eckert, K. Eckert, S. Heitkam
  
• X-ray and neutron radiographic experiments on particle-laden molten metal flows. In: J. Le, et al. (Eds.), Materials Processing Fundamentals 2021 (pp. 13–29), Springer International Publishing, 2021
  T. Lappan, M. Sarma, S. Heitkam, D. Mannes, P. Trtik, N. Shevchenko, K. Eckert, S. Eckert
  
• 9] J. Fröhlich, T. E. Hafemann, R. Jain, Phase-resolving direct numerical simulations of particle transport in liquids – from microfluidics to sediment, GAMM-Mitteilungen, 45:e202200016, 2022
  J. Fröhlich, T. E. Hafemann, R. Jain
  
• Particle tracking velocimetry in liquid gallium flow around a cylindrical obstacle. Experiments in Fluids, 63(6):99, 2022
  M. Birjukovs, P. Zvejnieks, T. Lappan, M. Sarma, S. Heitkam, P. Trtik, D. Mannes, S. Eckert, A. Jakovics