A Technological Review on Measurements of Electrical Conductivity for Metallurgical Ionic Melts
LAO Yigui1,2,3, GAO Yunming1,2,3, WANG Qiang1,2, LI Guangqiang1,2
1 Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 2 Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking, Wuhan University of Science and Technology, Wuhan 430081 3 Hubei Provincial Engineering Technology Research Center of Metallurgical Secondary Resources, Wuhan 430081
Abstract: 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.
1 Schiefelbein S L. Review of Scientific Instruments,1998,69(9),3308. 2 Robbins G D. Journal of the Electrochemical Society,1969,116(6),813. 3 Malki M, Echegut P. Journal of Non-Crystalline Solids,2003,323(1-3),131. 4 Dai X, Zhang C F. Nonferrous Metals,2005(4),2(in Chinese). 戴曦,张传福.有色金属(冶炼部分),2005(4),2. 5 Hara S, Hashimoto H, Ogino K. Transactions of the Iron and Steel Institute of Japan,1983(23),1053. 6 Ogino K, Hashimoto H, Hara S. Tetsu-to-Hagane,2010,64(2),225. 7 Kim K B, Sadoway D R. Journal of the Electrochemical Society,1992,139(139),1027. 8 Kim K B. Journal of the Electrochemical Society,1992,139(8),2128. 9 Wang S, Li G, Lou T, et al. ISIJ International,2007,39(11),1116. 10 Korenko M, Priš zák J, imko F. Chemical Papers,2013,67(10),1350. 11 Segers L, Fontana A, Winand R. Canadian Metallurgical Quarterly,2014,22(4),429. 12 Sun C, Guo X. Transactions of Nonferrous Metals Society of China,2011,21(7),1648. 13 Simonnet C, Phalippou J, Malki M, et al. Review of Scientific Instruments,2003,74(5),2805. 14 Macdonald C J, Huang G, Pal U B, et al. Office of scientific & technical information technical reports, U.S. Department of Energy, USA,2000. 15 Hundermark R J, Jahanshahi S, Sun S. In: International Conference on Molten Slags, Fluxes and Salts. Cape Town,2004,pp.487. 16 Barati M, Coley K S. Metallurgical & Materials Transactions B,2006,37(B),41. 17 Apisarov A P, Kryukovskii V A, Zaikov Y P, et al. Russian Journal of Electrochemistry,2007,43(8),870. 18 Dedyukhin A, Apisarov A, Tkacheva O, et al. ECS Transactions,2009,16(49),317. 19 Apisarov A A, Redkin A A, Zaikov Y P, et al. Journal of Chemical & Engineering Data,2011,56(12)4733. 20 Mitchell A, Cameron J. Metallurgical & Materials Transactions B,1971,2(12),3361. 21 Bacon G, Mitchell A, Nishizaki R M. Metallurgical Transactions,1972,3(3),631. 22 Hu X W, Wang Z W, Gao B L, et al. Journal of Northeastern University (Natural Science),2008,29(9),1294(in Chinese). 胡宪伟,王兆文,高炳亮,等.东北大学学报(自然科学版),2008,29(9),1294. 23 Wang Z W, Hu X W, Gao B L, et al. Journal of Northeastern University (Natural Science),2006,27(7),786(in Chinese). 王兆文,胡宪伟,高炳亮,等.东北大学学报(自然科学版),2006,27(7),786. 24 Pal U B, Macdonald C J, Chiang E, et al. Metallurgical & Materials Transactions B,2001,32(6),1119. 25 Fellner P, Midtlyng S, Sterten A, et al. Journal of Applied Electrochemistry,1993,23(1),78. 26 Fellner P, Kobbeltvedt O, Sterten A, et al. Electrochimica Acta,1993,38(4),589. 27 Hiveš J, Thonstad J, Sterten A, et al. Metallurgical & Materials Transactions B,1996,27(2),255. 28 Híveš J, Thonstad J. Electrochimica Acta,2004,49(28),5111. 29 Kubiňáková E, Híveš J, Danielik V. Acta Chimica Slovaca,2016,9(2),141. 30 Xie H W, Wang J X, Zhai Y C, Hu X Y, et al. The Open Materials Science Journal,2011,5(1),83. 31 Liang L K, Guo Z W, Wang Y Z, et al. Journal of Northeastern University (Natural Science),1985(3),74(in Chinese). 梁连科,郭仲文,王云志,等.东北大学学报(自然科学版),1985(3),74. 32 Yim E W, Feinleib M. Journal of the Electrochemical Society,1957,104(10),622. 33 Redkin A, Zaikov Y, Tingaev P, et al. Ionics,2013,19(12),1949. 34 Jia Z. Electrochimcal measurement method, Chemical Industry Press, China,2006(in Chinese). 贾铮.电化学测量方法,化学工业出版社,2006. 35 Hills G J, Djordjevic' S. Electrochimica Acta,1968,13(7),1721. 36 Tomkins R P T, Janz G J, Andalaft E. Journal of the Electrochemical Society,1970,117(7),125. 37 Ogino K, Hara S. Tetsu-to-Hagane,1977,63(13),2141. 38 Wang X W, Ray D P, Tabereaux A T. In: Light Metals. San Diego,1992,pp.481. 39 Liao C F, Wang K, Wang X, et al. Nonferrous Metals Science & Engineering,2013(5),19(in Chinese). 廖春发,王坤,王旭,等.有色金属科学与工程,2013(5),19. 40 Voronin B M, PrisyazhnyiV D, et al. Ukrainskii Khimicheskii Zhurnal,1980(46),229. 41 Schiefelbein S L, Sadoway D R. Metallurgical & Materials Transactions B,1997,28(6),1141. 42 Schiefelbein S L. A new technique to measure the electrical properties of molten oxides. PhD. Thesis, Massachusetts Institute of Technology, USA,1996. 43 Schiefelbein S L. High Temperature Materials & Processes,2001,20(3-4),247. 44 Verein Deutscher Eisenhüttenleute (VDEh). Slag atlas, Verlag Stahlei-sen GmbH, Germany,1995. 45 Fried N A. Electrical properties of binary solutions of molten titanium dioxide-barium oxide. PhD. Thesis, Massachusetts Institute of Technology, USA,1996.