Process Metallurgy and Electrochemistry of Molten Salts, Liquid Metal Batteries, and Extra-terrestrial Materials Processing: An EPD Symposium in Honor of Don Sadoway: Prof. Sadoway Honorary Session II
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee, TMS: Process Technology and Modeling Committee, TMS: Pyrometallurgy Committee
Program Organizers: Antoine Allanore, Massachusetts Institute of Technology; Hojong Kim, Pennsylvania State University; Takanari Ouchi, University of Tokyo; Yasuhiro Fukunaka, JAXA/Waseda University
Wednesday 2:00 PM
February 26, 2020
Room: 14A
Location: San Diego Convention Ctr
Session Chair: Hojong Kim, Pennsylvania State University; Takanari Ouchi, University of Tokyo
2:00 PM Introductory Comments
2:05 PM
Application of Electronically Mediated Metallothermic Reductions in Molten Salts to Nuclear Materials: Michael Simpson1; Prashant Bagri2; Jarom Chamberlain1; 1University of Utah; 2Oak Ridge National Laboratory
In 1999, Okabe and Sadoway published a seminal paper that explained metallothermic reduction in molten salts as an electronically mediated reaction. In the subsequent decades, this class of reactions has been applied to numerous nuclear materials-related processes. Examples include beryllium redox control in molten LiF-BeF2, direct electrolytic reduction of UO2 in molten LiCl-Li2O, and galvanic reduction of UCl3 in molten LiCl-KCl. These reactions have enormous potential for impact on the future of nuclear energy, as they can support fusion, recycling of conventional nuclear fuel, and minimization of waste from molten salt fueled fission reactors. This presentation will review these reactions, present some of the interesting results obtained from our experimental investigations, and relate those results to the theory of electronically mediated metallothermic reduction. Each electronically mediated reaction will be classified as short range, long range, or both with the consequences discussed.
2:25 PM Invited
Development of a New Electrodeposition Process based on Liquid Metal Electrochemical Technologies in Molten Salt Electrolytes: Takanari Ouchi1; Shuang Wu1; Toru Okabe1; 1The University of Tokyo
A liquid metal battery consisting of liquid metal positive and negative electrodes separated with a molten salt electrolyte was developed to satisfy the demands of large-scale electrochemical energy storage devices based on the technologies of electrowinning and electrorefining in molten salt. In order to develop liquid metal batteries, the electrochemical behavior of the liquid metal electrodes in the molten salt electrolyte was carefully investigated. It was observed that some metals in the positive electrodes dissolved as anions in the molten salt, and that the anions electrochemically oxidized to form their metals under application of the appropriate voltages. This has long been known to occur, but has not yet been understood well. Recent research on a new electrodeposition process of metals using this anodic deposition will be introduced.
2:45 PM Invited
Electrodeposition of Titanium from Alkali Fluoride-Chloride Molten Salts: Yutaro Norikawa1; Makoto Unoki1; Kouji Yasuda1; Koma Numata2; Mitsuyasu Ogawa2; Masatoshi Majima2; Toshiyuki Nohira1; 1Kyoto University; 2Sumitomo Electric Industries, Ltd.
Electroplating is a promising approach to utilize the superior properties of titanium, such as corrosion resistance and biocompatibility. Even complex-shaped materials can be coated by electroplating. Generally, compact and smooth Ti films were obtained from fluoride melts such as LiF–NaF–KF. However, one of the problems using fluoride-based molten salts was the difficulty in removing the salt adhered to the deposited Ti due to low solubility of LiF and NaF in water. Recently, we have proposed a new electrodepositon process of Ti using water-soluble KF–KCl molten salts. This paper presents the electrodeposition of Ti and the electrochemical behavior of Ti(III) ions in molten KF–KCl. Moreover, comparison with the results obtained in LiF–LiCl will be given to discuss the effect of cations on the electrochemical behavior of Ti ions.
3:05 PM Invited
History of Inventions and Innovations for Aluminum Production: Michel Reverdy1; Vinko Potocnik2; 1Emirates Global Aluminium; 2Vinko Potocnik Consultant Inc
Industrial production of aluminum started in 1856 with the chemical method developed by Sainte-Claire Deville which produced 200 tonnes of aluminum until 1890. In 1886 Charles Hall and Paul Héroult invented the electrolytic reduction of alumina with carbon which quickly became the only method used to produce aluminum until today. Even though the Hall-Héroult process remained the same, the production technology changed tremendously since the beginning, to reduce specific energy consumption, increase productivity and improve environment. In this paper, the most notable inventions and innovations for improvement of the Hall-Héroult process in the last 100 years will be described as well as efforts to break away from this process, which all have been unsuccessful. These include direct reduction of alumina with carbon and the aluminum chloride process. Within the electrolysis process, until now unsuccessful research to use non-consumable anodes and wettable cathodes for large-scale production will also be described.
3:25 PM Break
3:45 PM Invited
Open-circuit Explosions and Basement Thermite Fires Threaten Aluminum Potlines
: Alton Tabereaux1; 1Consultant
Four aluminum smelters have experienced an open-circuit arc-flash explosion in an individual cell which resulted in lengthy electrical power interruptions greater than four hours and shutting down all the other cells in potlines. Two smelters continued to operate potlines after an open-circuit incident when the power outage was less than three hours. Five aluminum smelters experienced basement thermite fires in an individual cell due to the spillage of molten aluminum into the basement. Three of these smelters shut-down all the cells in the potline due to lengthy power interruptions. Two smelters were able to continue operation after the thermite fire by constructing a temporary by-pass conductor around the damaged cell in less than threes hours. This article examines the various causes and mechanism of open-circuit explosions and thermite fires in individual cells and explores some of the pathways that smelters can use to possibly prevent and/or survive these dangerous incidents.
4:05 PM Invited
Study on Electronically Mediated Reaction (EMR), and What I Learned from Professor Sadoway: Toru Okabe1; 1University of Tokyo
The fundamental aspects of an electronically mediated reaction (EMR) and its usefulness for metal production will be explained with some experimental evidences. EMR provides an effective method for controlling the location and morphology of the metal deposit. Recent progress on the study on EMR will be introduced along with memories working with Professor Sadoway.
4:25 PM Invited
Thermodynamics of Electrode Reactions for Energy Storage, Separation, and Corrosion: Hojong Kim1; 1Pennsylvania State University
Understanding thermodynamics of electrode reactions is essential for a successful design of electrochemical processes for production of metals, batteries, and corrosion-resistant alloys in aggressive chemical environments. This work presents electrochemical approaches for determining thermodynamic properties of electrode reactions based on electromotive force (emf) measurements of alloy electrodes (e.g., Li-Bi, K-Bi, Ca-Bi) in solid electrolytes and cyclic voltammetry technique in molten salts (e.g., SO42‒ and Te2‒). The development of stable reference electrodes (e.g., Ca-Bi) in a given electrolyte (e.g., CaF2) is an important consideration for reliable electrochemical measurements and thus, the selection criteria and compatibility of cell components are presented. Reliable thermodynamic properties provided crucial insights into the design of electrode materials for liquid metal batteries, the separation of energy-critical materials such as alkaline-earth (Sr, Ba) and rare-earth (Nd, Gd) elements, and the strategies to control the degradation reactions of structural components in molten salt solutions.
4:45 PM Invited
Trends and Challenges for Electrowinning of Aluminium and Magnesium from Molten Salt Electrolytes: Geir-Martin Haarberg1; 1Norwegian University of Science & Technology
Modern aluminium producing cells are operating at ~ 955 - 965 oC. The current efficiency with respect to aluminium can be as high as 96 % and the corresponding energy consumption may be ~13 kWh/kg Al and higher in cells running at ~ 300 kA or higher. The current density is ~0.9 A/cm2. Developing inert anodes for oxygen evolution and measures to eliminate PFC emissions are important research topics.Today magnesium is mainly produced by the Pidgeon process, which involves the reduction of MgO by silicon in the form of ferrosilicon. The thermal process is presently more economic but electrowinning in molten chlorides with MgCl2 feedstock may be more sustainable and may make a comeback. However, electrolysis is still important for producing magnesium in the Kroll process for titanium production. The presence of moisture will affect the collection of produced Mg droplets and the consumption of graphite anodes.
5:05 PM Invited
Extraction of Magnesium from Aluminum Scrap Melts by Molten Salt Electrorefining: John Hryn1; Subodh Das2; Boyd Davis3; 1Argonne National Laboratory; 2Phinix; 3Kingston Process Metallurgy
This presentation will describe a 300A molten salt electrorefining cell that was constructed to recover magnesium from aluminum scrap melts.