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 & Electrodes Technology Session
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
Tuesday 2:30 PM
March 21, 2023
Room: 30E
Location: SDCC
Session Chair: Evan Andrews, Boyne Smelters Limited
2:30 PM Introductory Comments
2:40 PM Invited
The Need to Respect to the Interlink between Science, Physics, and Cell Design in an Environmentally Responsible Manner - The Next Big Challenge for Aluminium Smelting: Barry Welch1; 1University of Auckland; University of New South Wales
Building on the scientific and practical knowledge outstanding energy efficient smelting cell designs have been developed that are energy efficient and environmentally responsible. With constraints arising from regional availability of energy and the substantial cost of supporting infrastructure , capacity creep by increasing amperage on the installed capacity provides the best way of satisfying the growth in demand for the metal. Invariably design and operating retrofits become desirable or necessary because of heat balance and other constraint. Adverse performance and operating characteristics, such as a substantial reduction in cell life or reduced efficiencies. The root cause is invariably being due to changes of transfer processes - the physics of getting the consumables or energy to or from the reacting sites at the rate required in order to maintain the desired uniformity in the cell. Hitherto this has been ignored - avoiding or minimising is the next challenge.
3:05 PM
Anode Quality Optimisation – Industry Learnings from the Research Supervised by Barry Welch: Alan Tomsett1; Barry Sadler2; 1Rio Tinto Pacific Operations; 2Net Carbon Consulting
Barry Welch has a long history of supporting carbon anode research from the perspective of both the anode producer and the potroom customer. The outcomes of this research from Barry and his students continue to be essential reading for anode producers and technologists. The key publications of Barry’s students will be reviewed to provide a summary of this important body of work and to reinforce the significance of Barry’s contribution to the aluminum industry.
3:30 PM Invited
Process Recovery to Unlock Power Efficiency Improvement at BSL: Evan Andrews1; Thomas Booby1; Murray Ure1; Hao Zhang2; 1Boyne Smelters Limited; 2Transformation and Technical Support, Pacific Operations
In February 2019, Boyne Smelters Limited (BSL) established a project team to recover Reduction Line 3 from a process excursion. The Line 3 operation had deteriorated progressively through 2018, with increasing levels of cell instability, anode spiking and work handed over between shifts had reached critical levels. By January 2019, average current efficiency had dropped to 91.7% and power efficiency had climbed to 13.45 DCkWhr/kgAl. The recovery project ran for 2 months and quickly achieved stable operation through a series of project clusters targeting exception cell recovery, new cell control and management of intergenerational cell designs. An average of 64mV was saved in 2019 compared to 2018, representing a power efficiency improvement of 0.24 DCkWhr/kgAl. Further stabilisation into 2020, resulted in full year performance of 94.2% and 12.96 DCkWhr/kgAl current efficiency and power efficiency respectively. This paper describes the fundamental approach taken to problem solve and deliver value quickly.
3:55 PM
A Smart Individual Anode Current Measurement System and Its Applications: Choon-Jie Wong1; Jing Shi1; Jie Bao1; Barry Welch1; Maria Skyllas-Kazacos1; Ali Jassim2; Mohamed Mahmoud2; Konstantin Nikandrov2; 1University of New South Wales; 2Emirates Global Aluminium
This paper discusses a new individual anode current measurement scheme and its applications in real-time monitoring and control of the Hall-Héroult process. While anode current can be directly measured from the anode rod, this approach takes measurements from the anode beam allowing the sensors to remain intact through various cell operations, including anode change. This instrumentation scheme employs smart sensors that are daisy-chained on a common bus for digital data transfer. This approach limits electromagnetic interferences and offers system self-configuration and self-diagnosis, thus allows easy maintenance. The system can be configured to work across a broad range of cell technologies. Monitoring anode current distributions helps improve process operation and allows early detection of process faults such as perfluorocarbon co-evolution and blocked feeders. This also offers the ability to monitor process states such as local alumina concentration and anode-cathode distance, and potential improvements to cell operation and current efficiency.
4:20 PM Break
4:35 PM
Light Metals Research at the University of Auckland: James Metson1; Ron Etzion1; Margaret Hyland2; 1University of Auckland; 2Victoria University of Wellington
The University of Auckland has had a more than 40 year history of research contributions in support of the light metals industries. This was initiated with the appointment of Professor Barry Welch in Chemical and Materials Engineering, but subsequently broadened to embrace academics across a range of disciplines, particularly in chemical sciences. An initial focus in the aluminium and alumina industries has extended into lithium, magnesium and titanium. A defining character of this work has always been close engagement with the light metals industries, however over time the nature of this interaction has evolved. Of note has been convergence on a range of industry defining and challenging issues where cross-sector collaborations, often working closely with government agencies, have progressively paralleled a range of individual projects addressing technical advantage. Environmental footprint and response to a dynamic energy environment are prominent within this this common ground. These trends will be examined along with potential future directions for this research relationship.
5:00 PM
Impact of Aluminium Reduction Cell Parameters on Feeder Hole Condition: Pascal Lavoie1; Mark Taylor2; 1Alcoa; 2University of Auckland
Aluminium reduction requires alumina to be fed and dissolved into electrolyte. The feeder hole condition may impact severely the ability to dissolve the added alumina. In this study, two sets of observations were made on a large sample of aluminium reduction cells to understand the feeder hole condition progress during feed events and determine which reduction cell parameters affect the feeder hole condition and the progression pathway of the feeding event sequence. The results show that feed rate has a major impact on the initial feeder hole condition and is determinant to the pathway of the feeding sequence. Higher superheat, lower excess AlF3 and longer time since the last anode change increased the probability of finding feeder hole conditions conducive to dissolution. The observations of blocked feeder holes were found to be linked to abnormal process conditions or a mechanical issue. Changes made to the feeding strategy between the two observation sets led to a significant improvement of the feeder hole condition. The proportion of opened feeder holes increased from 12% to 41%, resulting in a more than 50% reduction of the anode effect frequency smelter-wide.
5:25 PM
A Dynamic Coupled Mass and Thermal Model for the Top Chamber of the Aluminium Smelting Cells: Luning Ma1; Choon-Jie Wong1; Jie Bao1; Maria Skyllas-Kazacos1; Barry Welch1; Nadia Ahli2; Mohamed Mahmoud2; Konstantin Nikandrov2; Amal Aljasmi2; 1The University of New South Wales; 2Emirates Global Aluminium
The bath temperature of a Hall-Héroult cell is an important process variable which affects the aluminium smelting process conditions including the superheat, the alumina dissolution and the energy consumption. However, it cannot be easily measured continuously for real-time monitoring. This paper presents a thermal model of a Hall-Héroult cell and its top chamber, and proposes the use of an extended Kalman filter as a model-based state observer to estimate the average bath temperature continuously in real-time under different process operation scenarios from the variables including the duct gas temperature and velocity. The proposed approach helps improve online operation of aluminium smelting cells by maintaining appropriate thermal balance including superheat and aluminium fluoride level.
5:50 PM Concluding Comments