60 Years of Taking Aluminum Smelting Research and Development from New Zealand to the World: An LMD Symposium in Honor of Barry J. Welch: Joint Barry Welch Honorary Symposium - Reduction Technology Session- Alumina Feeding, Process Control, Modelling & Industry 4.0
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Mark Dorreen, CSIRO; Alan Tomsett, Rio Tinto Pacific Operations; David Wong, Atmolite Consulting Pty Ltd; Linus Perander, Yara International; Barry Sadler, Net Carbon Consulting Pty Ltd; Stephan Broek, Kensington Technology Inc
Wednesday 8:30 AM
March 22, 2023
Room: 30E
Location: SDCC
Session Chair: Martin Segatz, Hydro Aluminium Limited; Sylvain Fardeau, Trimet France
8:30 AM Introductory Comments
8:35 AM
Following Alumina Dissolution Kinetics with Electrochemical and Video Analysis Tools: Daniel Marinha1; Astrid Meyer2; Marían Kucharik2; Sylvie Bouvet1; Miroslav Boca3; Frantisek Simko3; Michal Korenko3; Vladimir Danielik3; 1Rio Tinto Aluminium; 2Hydro Aluminium; 3Slovak Academy of Sciences
The rate of alumina dissolution in cryolitic melts is critical for the management of aluminum production pots. The kinetics of the dissolution reaction depends on the combined effects of physical and chemical characteristics of alumina. The literature mentions several methods to follow the rate of dissolution, with variable degrees of complexity and success. We report a combination of analytical tools to evaluate the dissolution rates of various industrial aluminas in an industrial cryolite bath collected shortly before the anode-effect. Batches of powders were sequentially added to an electrochemical cell specifically designed for this test. The dissolution rate was measured electrochemically, and an automatic script was developed to measure the flotation time of the alumina rafts from digital recordings. From the results, we can correlate the alumina dissolution rate and flotation times, with the initial characteristics of the alumina powder.
9:00 AM
Monitoring Cell Conditions and Anode Freeze Dissolution with Model-based Soft Sensor After Anode Change: Choon-Jie Wong1; Jie Bao1; Maria Skyllas-Kazacos1; Ali Jassim2; Mohamed Mahmoud2; Alexander Arkhipov2; 1University of New South Wales; 2Emirates Global Aluminium
Carbon anodes in Hall-Héroult cells are consumed continuously and changed periodically. The anode change operation introduces major energy deficit which adversely perturbs the mass and heat balance of the cell. The freeze formed underneath the newly-replaced anodes impedes normal bath circulation and mixing, removes local heat as it dissolves, and disrupts the normal anode current flow which deforms the metal pad via magnetohydrodynamic forces. These exacerbate the spatial non-uniformity in a cell which may lead to increased process faults and loss of process efficiency. This paper proposes the use of individual anode current measurements to monitor the dissolution of anode freeze in real-time. This helps to return the cell to nominal operation conditions quickly, by identifying issues such as low local superheat, as well as by enabling further improvements to operational procedures such as ACD adjustments for new anodes. This improves process and energy efficiencies following anode change operations.
9:25 AM Invited
EGA’s First Holistic Mobile Application for Smelter Operations
: Ahmed Al Haddad1; 1Emirates Global Aluminium
Artificial Intelligence has the potential to generate a significant amount of business value and support EGA’s strategic ambitions and value of innovation and continuous improvement. In order to build a highly performing machine learning model we need to fuel the engine with a large amount of quality data for example “approximately 1.6 million sheets of paper are consumed annually in Reduction”. This is where SAQR – an advanced mobile application can unlock new value via digitization, automation and enable future AI implementation. The SAQR application is expected to enhance EGA’s data collection, increase overall accuracy and provide transparent tracking throughout our operations, enabling faster decision making. The team behind SAQR is now focused on extending its reach within EGA - SAQR is currently being used in potlines, crucible tracking, technology, reduction process control and busbar monitoring. Today we have full visibility of every crucible journey within EGA.
9:50 AM Invited
Testing Feeding Alumina in Three Channels in a Wide Cell: Marc Dupuis1; Valdis Bojarevics2; 1GeniSim Inc.; 2Greenwich University
For years Barry Welch has been promoting the idea to designing wider cells. Some preliminary modelling work [1,2] already demonstrated some of the advantages of using wider cells like reducing external potshell area per electrolysis area ratio that help the design a low energy consumption cells and the potshell length to width ratio that help designing even higher amperage cells without further increasing the potroom width and hence the crane span. A third advantage is to help reduce the formation of alumina concentration in the bath by allowing the addition of two new alumina feeding channels. The MHD cell stability code MHD-Valdis including its alumina dissolution module has been updated to support the addition of two extra longitudinal feeding channels in order to study the impact using three channels to feed alumina into the cell. Results obtained will be presented.
10:15 AM Break
10:30 AM
A Pragmatic Model for Bath Temperature Evolution during Alumina Feeding: Kurian J. Vachaparambil1; Stein Tore Johansen1; Asbjørn Solheim1; Kristian Etienne Einarsrud2; 1SINTEF; 2Norwegian University of Science and Technology (NTNU)
In this paper we present the advances made towards including a model for bath temperature variations in the pragmatic framework for alumina feeding which was presented in TMS 2022. The framework utilizes a coarse grid with special numerical techniques to allow for faster than real-time simulations. Based on the concepts of pragmatism in industrial modelling, the spatial and temporal evolution of the bath temperature is modelled. The bath temperature model considers the effect of ohmic heating, heating of the cold alumina particles which are fed, alumina dissolution, heat lost through sidewalls, top canals, and metal as well as via the anodes. The alumina dissolution and distribution are connected to the energy balance as the bath temperature impacts the solubility and the physical properties that controls dissolution. Accordingly, we can see some changes to the dynamics of the aluminium reduction cell. The model runs typically much faster than real time.
10:55 AM
A New Strategy for Transient Heat Transfer Models with Phase Change for the Aluminum Electrolysis Industry: Bastien Pansiot1; Marc Lebreux1; Martin Désilets1; Francis Lalancette1; Jean-Francois Bilodeau2; Alexandre Blais2; 1Université de Sherbrooke; 2Rio Tinto Alcan
The heat balance of an Aluminum Electrolysis Cell (AEC) represents a very sensitive aspect of its operation. Steady state heat balance is quite well understood thanks to industrial expertise and widely used steady state finite elements models. With the increasing interest of power modulation, these tools become insufficient to predict the time dependent heat balance of the cell. Above all, they are not suited to predict the melting or formation of the side ledge, a protective solid layer formed on the cell to avoid the corrosive action of the liquid electrolytic bath on the sidewalls. The authors developed a new thermal-electrical model coupling ANSYS Mechanical software and Python, able to compute the transient heat balance of an AEC, including the phase change dynamic of the side ledge and thermal contact resistance. It has been found to give both accurate results and improved computational time.
11:20 AM
Development and Deployment Measures in PLC-based Pot Control System at Low Amperage Aluminium Reduction Cell: Rajeev Yadav1; Shanmukh Rajgire1; Md.Imroz Ahmad2; Goutam Das2; Ravi Pandey2; Mahesh Sahoo2; Amit Gupta1; 1Aditya Birla Science and Technology Company (P) Ltd; 2Hindalco Industries Ltd
Hirakud 85kA, end-to-end potline was converted to prebake with GAMI technology during 2006-2009. Later, it was observed that, in the existing pot control system, the application software and control modules are encrypted and hence difficult to modify in line with process requirements. Therefore, control logic and PLC-based system were developed in-house, in correspondence to the Hirakud pot design and process. During the implementation of the new control system, the primary challenges were the acceptability on shop floor and high pot instability due to sludge forming tendency. Also, preventive, and corrective measures are delayed due to high manually intensive operations. To mitigate the above challenges, following actions were taken. (a) technical training was provided to the shop floor personals. (b) Developed control logic was modified based on pot conditions. (c) SCADA features, additional reporting, and auto mailing were developed. This article would provide detailed insight about the development and deployment measures.
11:45 AM
A Discussion on Thermal Impact of Anode Change in Aluminum Reduction Cell: Zhibin Zhao1; Wei Liu1; Yafeng Liu1; Michael Ren2; 1Shenyang Aluminum and Magnesium Engineering and Research Institute Co. Ltd.; 2Sunlightmetal Consulting Inc.
Anode change is the most important operation in aluminum electrolysis industry. Influence of new anodes are mainly concentrated in two aspects: a) huge impact on thermal balance of reduction cells by massive anodes with low temperature and b) newly settled anodes wrapped by a layer of insulating solidified electrolyte generates remarkable horizontal current in aluminum pad. This paper only focuses on thermal impact of anode change. The paper theoretically calculates heat absorption of new anodes and heat release of additional voltage, metal/bath temperature decrease, and ledge solidification. An interim summary was proposed. A new finding is introduced that the anode change in one pot has an individualized characteristic, for which different additional voltage strategies should be applied. An industrial trial has been conducted here. Some methods for decreasing thermal impact of anode change, including anode pre-heating, inert anodes and continuous anodes were also discussed and analyzed.
12:10 PM Concluding Comments