Development of a calibration free high-temperature electrical conductivity measurement for $CaF_{2}$ melts and slag systems

  • Calibration-free electrical conductivity measurement for $CaF_{2}$ slags

Borowski, Nikolaus Peter Kurt; Friedrich, Bernd (Thesis advisor); Reuter, Markus Andreas (Thesis advisor)

Düren : Shaker Verlag (2023)
Book, Dissertation / PhD Thesis

In: Schriftenreihe des IME 82
Page(s)/Article-Nr.: XV, 165 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2022


The specific electrical conductivity of slags is a thermo-physical property that strongly influences the power consumption of metallurgical smelting processes that are based on the principle of resistance heating. Currently, worldwide no measurement technology is available to precisely measure the electrical conductivity of CaF2 and its slag systems up to high temperatures (~1,750 °C). Therefore, the aim of this thesis is to develop a measurement technology that is calibration-free, achieves highest accuracy and stable measurement results over a broad conductivity spectrum up to high temperatures of ~1,750°C. The herein developed technology combines well-known best-practice examples, e.g. cell design, measurement technique and measurement method (electrochemical impedance spectroscopy) with an innovative data evaluation process based on simulation of the measurement and fitting of equivalent circuit diagrams to a new measurement technology. The developed technology is evaluated in several aqueous solutions at room temperature, molten KCl and NaCl as well as in molten CaF2. The technology is tested on its robustness and calibration-freeness, accuracy and overall measuring error over a wide temperature range from 16 °C up to 1,720 °C and over an electrical conductivity range starting from 1.356 mS/cm up to ~7 S/cm. Finally, the technology limitations are determined and an outlook to further optimization options is given.


  • Division of Materials Science and Engineering [520000]
  • Chair of Process Metallurgy and Metal Recycling [522610]