Vibration measurements provide a promising approach for regulating gas stirring intensity in metallurgical ladles. In this work, vibration measurements are conducted during argon injection into an experimental ladle filled with Sn–40 wt% Bi at 200 °C, integrated into the Liquid Metal Model for Steel Casting facility at Helmholtz-Zentrum Dresden Rossendorf, Germany. Three high-sensitivity accelerometers record vibrations during systematic changes in gas flow rate and pressure above the top free surface. The vibration signals are correlated with visual observations of the free surface to validate bubble behavior and surface disturbances. Results demonstrate that vibration signals qualitatively characterize bubble number and size, with specific frequency ranges associated with bubble formation and collapse. Furthermore, a reduction in pressure at the top free surface leads to an increase in the recorded root mean square vibration values, accompanied by a shift of single-bubble generation to lower frequencies and bubble bursting to higher frequencies. Signal analysis enables the distinction between single bubble flow and regimes where bubble–bubble interactions may occur. The study establishes a fundamental connection between evolving bubble dynamics and the vibrational response of two-phase flows. Data from this work can be used to develop more accurate vibration-based models for stirring monitoring in steelmaking processes.

Vibration measurements are being conducted at an industrial ladle containing molten steel during vacuum degassing at Uddeholms AB, Hagfors, Sweden, using three highly sensitive accelerometers. The accelerometers are installed at different radial positions on the ladle-carrying car to record vibrations generated during argon gas injection under vacuum conditions, in order to study the vibrations generated in an industrial-scale ladle. To gain deeper fundamental knowledge and understanding, a similar methodology and measuring equipment are implemented at a laboratory-scale ladle operating with liquid Sn–40 wt% Bi alloy at 200 °C, integrated into the liquid metal model for steel casting facility at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The results indicate that bubble evolution events generate vibrations within comparable frequency ranges in both settings. A low-frequency band (100–300 Hz) is observed, associated with bubble generation at the stirring plugs and higher frequency signals (900–1600 Hz) are linked to bubble rupture at the slag-melt interface. The study demonstrates that analyzing the signals in those frequency bands can support the correct installation of gas flow rate and the assessment of gas injection conditions in steelmaking ladles. This study provides fundamental insights for interpreting vibration signals in an industrial setting.

In recent years there is an attempt to control the gas stirring intensity in metal-making ladles with the aid of vibration measurements. Understanding better the induced vibrations in two-phase flows can substantially improve the existing models for gas stirring control. In this work, highly sensitive accelerometers were used for the vibration measurements in a liquid metal alloy; Sn–40 wt pctBi alloy at 200 °C and water at 20 °C. The examination of the liquids was conducted in the ladle mockup integrated into the Liquid Metal Model for Steel Casting facility at Helmholtz-Zentrum Dresden Rossendorf. Single bubbles were generated in the respective liquids by controlled argon injection at low flow rates in the range of 0.01 to 0.15 NL min −1 through a single nozzle installed at the bottom of the ladle. Obtained results demonstrate differences between the induced vibrations in the examined liquids in terms of the magnitude of the root mean square values of vibration amplitude and the shape of the resulting curves with increasing flow rate. Furthermore, continuous wavelet transform reveals variations in the duration and vibrational frequency of the evolved bubble phenomena. The findings suggest that differences in the physical properties of the examined liquids result in variations in the vibrations induced during bubble evolution.

Vibration measurements were carried out using highly sensitive accelerometers in an experimental ladle integrated into the LIMMCAST (Liquid Metal Model for Steel Casting) facility at HZDR. The model is operated with liquid Sn–40 wt pctBi alloy at 200 °C, whose physical properties are close to those of molten steel. Three accelerometers were attached to the outer wall of the LIMMCAST vessel to record the vibrations caused by the argon bubble flow in the liquid metal at different process parameters. The results obtained at the liquid metal experiments differ from those reported for water models where the relationship between root mean square (RMS) value of the vibration amplitude and the gas flow rate follows different curve shapes. Furthermore, the results of vibration measurements in the LIMMCAST model are compared with vibration measurements in a steel plant during vacuum degassing. The comparison of the RMS data shows a fairly good agreement. This indicates that the vibrations in both the industrial process and the laboratory model are caused by the same physical mechanisms, and thus, the vibration behavior in an industrial steelmaking ladle can be reproduced quite well by suitable liquid metal models. These studies on bubble flows can help to improve the understanding of industrial stirring processes and thus contribute to a better process control.

Thermal properties of green Söderberg electrode pastes were measured up to 1073 K (800 °C) using the transient plane source method. Comparison was made to measurements on an electrode material baked beforehand to 1473 K (1200 °C). For the green pastes, thermal conductivity was found to decrease up to 673 K (400 °C) at the onset of baking. After about 873 K (600 °C), thermal conductivity of the material increases with increasing temperature. For previously baked Söderberg material, thermal conductivity continually increases with increasing temperature.