Methodology Development of Electrical Conductivity Measurements for Iron Silicate Slags

An experimental setup and methodology for high-temperature electrical conductivity experiments on iron silicate slags was developed with the aim to investigate the dependency of the electrical conductivity on the iron redox state. The main benefits of the utilized setup and methodology are (1) experiments can be performed in a controlled CO/CO₂ atmosphere, (2) the possibility to quench after the high-temperature experiment for sample characterization, and (3) the ability to separate ionic and electronic conductivity via combining impedance measurements with stepped potential chronoamperometry (SPC). To develop a suitable methodology, high-temperature experiments were conducted at three different atmospheres with an oxygen partial pressure of 10^–0.67 atm, 10^–5.01 atm, and 10^–7.92 atm for a CaO–SiO₂–AlO_1.5–‘FeO’ slag. It was found that the obtained electronic transference numbers were of similar magnitude as those reported in literature for slags with a similar ‘FeO’ content and an expected conductivity maximum was found as well. The experimental uncertainty of the current setup was found to vary between 20.2 and 32.2% for impedance measurements and the uncertainty was below 3% for the electronic transference numbers for the SPC technique.