Electrode Technology for Aluminum Production: Session III
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Stephan Broek, Kensington Technology Inc; Dmitry Eskin, Brunel University

Tuesday 2:30 PM
March 1, 2022
Room: 208A
Location: Anaheim Convention Center

Session Chair: Stephan Broek, Hatch

2:30 PM
Effects of Stub Preheating Temperature on the Anode Voltage Drop in the Aluminium Reduction Cell: Tuofu Li¹; Wenju Tao²; Zhaowen Wang²; ¹General Research Institute of Mining and Metallurgy Technology Group; ²Northeastern University
    The anode rodding process has significant effects on the anode performance in the cell. In this study, numerical simulations are conducted to investigate the effects of the stub preheating temperature before anode rodding on the anode voltage drop. Numerical simulation results show that the anode voltage drop increases from 295 mV with no stub preheating to 357 mV with the stub preheating temperature of 400 ℃. The reasons are analyzed as follows. With the stub preheating temperature increasing, the stub temperature during anode casting also increases, which leads to the increase in the initial cast iron-to-carbon air gap after anode rodding. When the anode with the enlarged initial cast iron-to-carbon air gap is running in the cell, the real contact area between the cast iron and the carbon becomes small, and the stub-to-carbon voltage drop, as well as the total anode voltage drop, increases.

2:55 PM
EGA Journey with Different Ramming Pastes: Ali Jassim¹; Najeeba Al Jabri¹; Alexander Arkhipov¹; Mohamed Tawfik Boraie¹; ¹EGA
    In alignment with EGA’s vision toward testing and adopting usage of safe materials in its cell construction and to ensure high safety standards for it is workers, EGA has adopted the usage of polycyclic aromatic hydrocarbons (PAH)-free ramming paste (eco-friendly paste) in certain potlines in its operating sites in Jebel Ali and Al Taweelah. The paper describes EGA’s journey toward the usage of different ramming pastes and presents required testing and evaluation changes prior to changing the ramming paste type. Performance of the latest types of PAH ramming pastes and comparison of the potlife with several PAH-free and traditional pastes used in EGA is also discussed.

3:20 PM
Molecular Dynamic Insights into Carbon Electrode Behaviors of Aluminium Electrolysis : Jiaqi Li¹; Jie Li¹; Jingkun Wang¹; Hongliang Zhang¹; ¹Central South University
    Carbon electrodes are considered as one of the most important components of aluminum electrolysis cells, which are closely related to the PFC gas emission and alkali metal penetration. In this work, the Lennard-Jones (L-J) potential parameters involving molten electrolytes and carbon electrodes were firstly calculate to represent ion-ion and ion-electrode interactions. Afterwards, the microstructure of different molten electrolytes were investigated based on molecular dynamics simulations, especially for ion distribution of electrode-molten salt interface region. Results show that the accumualtion of counter-ions around electrodes would form some stable electrical double layer (EDL) structures, which directly determine electrode properties such as capacitance values. Besides, the shift of ionic complex in surface layer deciphered the twin-peak behavior of electrolytes nearby carbon anodes. This fundamental research would contribute to a deeper knowledge of phenomena taking place near carbon electrodes and the optimization design of aluminum electrolytes.

3:45 PM
Quality Evaluation of Nitride Bonded SiC Sidelining Materials. Historical Trends 1997-2022 Including Results and Development of Test Methods: Egil Skybakmoen¹; ¹SINTEF Industry
    The replacement of carbon-based sidelining materials by ceramics, mainly silicon nitride bonded silicon carbide, started in the late 80's. The ceramics have higher thermal conductivity and better oxidation- and chemical resistance. The latter opened up the opportunity of using thinner linings, which again enabled larger anodes and higher productivity due to amperage increase. Alton Tabereaux was a pioneer in establishing quality evaluation for this kind of material by TMS papers in 1993 and 1994. Inspired of his work and industrial needs; SINTEF, sponsored by the Norwegian aluminium industry, started to evaluate and develop laboratory scale test methods in 1994 to be able to rank commercial materials from the global market. In this paper, we summarize our findings regarding material parameters and test methods during the last 25 years. Important information for suppliers as well as users of these types of lining materials are given.