Metallurgical ionic melt usually acts as the reaction medium or direct participant of heterogeneous smelting reaction involving electro-winning and metal refining, etc. at high temperature. Aiming at ensuring the smooth process of smelting, metallurgical ionic melt has to possess appropriate physical and chemical properties. As an important physicochemical property of metallurgical ionic melt, the electrical conductivity plays a dominant role in controlling the quality of products, production efficiency, energy consumption, cost during metallurgical production. In addition, the electrical conductivity is closely related to the structure of ionic melt, ionic migration, conductive mechanism and electrode reaction mechanism. The study of the electrical conductivity of metallurgical ionic melt is also contributed to the exploration of basic theories concerning metallurgy. Accordingly, it is of great significance to study the electrical conductivity in metallurgical field, and its accurate determination has always been a focus of attention of metallurgical researchers. Measurement of electrical conductivity of liquid electrolyte is commonly performed in a conductance cell. However, metallurgical ionic melt often holds high temperature, which brings about difficulties in determination, including the construction of appropriate conductance cell and the choice of electrode material. Under the guidance of measurement principle, diverse measurement techniques of conductivity have been developed. At present, the commonly used approaches for measuring the electrical conductivity of metallurgical ion melt consist of AC two-electrode technique, AC four-electrode technique, continuously varying cell constant (CVCC) technique and coaxial cylinders technique. AC two-electrode and AC four-electrode techniques hold widespread applications, owing to their relatively simple structure of the conductance cell, and the ease of obtaining the materials of the electrode and the conductive cell. Hence, it is widely used for monitoring the production process and the quick measurement of the conductivity data. Compared with AC two-electrode technique, the superiority of four-electrode technique lies in the separation of the electrodes of measuring voltage and current, and there is almost no current passing through the electrodes for measuring voltage, thus the consideration of electrodes and lead wires resistance can be avoided. Nevertheless, the two methods suffer from defects in the structure of the conductance cell, which makes the measurement accuracy difficult to grasp. The CVCC and the coaxial cylinders techniques are superior to the above two methods in the structure of the conductance cell, which makes them possess higher measurement accuracy and capable of applying in the case of higher precision requirements. Unfortunately, the structure of their conductance cell is usually rather complicated. Moreover, the CVCC technique requires specific materials to satisfy the experimental requirements under certain conditions, which leads to a higher experimental cost. Although the coaxial cylinders technique exhibits the advantage of calibration-free under the condition of electrode centered, the influence of the electrode deformation still exists at high temperature. Meanwhile, the measurement range of the electrical conductivity is limited by the size of the conductance cell that can be constructed under experimental conditions. In this article, the experimental technical experiences of the above four methods including measurement principles, relative merits of the techniques, operation and working conditions are summarized and compared; additionally, the relationship among the above four methods is also analyzed briefly, for the sake of providing guidance for measuring electrical conductivity of metallurgical ionic melt in laboratory. © 2019, Materials Review Magazine. All right reserved.
