Primary Aluminum Industry - Energy and Emission Reductions: An LMD Symposium in Honor of Halvor Kvande: Energy and Emission Reductions II: An LMD Symposium in Honor of Halvor
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Arne Ratvik, SINTEF
Wednesday 2:00 PM
March 2, 2022
Room: 208A
Location: Anaheim Convention Center
Session Chair: Arne Ratvik, SINTEF Industry
2:00 PM Introductory Comments
2:05 PM
A Historical Review of Aluminum Reduction Cell Start-up and Early Operation: Michel Reverdy1; Vinko Potocnik2; 1Emirates Global Aluminium; 2Vinko Potocnik Consultant Inc.
Start-up and early operation of aluminum reduction cells are very important for cell performance, life expectancy and environment. Several methods of cell start-up have been used over time, some early methods with no preheat, but using preheat has been more successful and remains the predominant method today. Ideally the cell should be preheated slowly to uniform operating temperature on the top of cathode blocks, but in practice this is rarely achieved and is different between companies. Bath-up and metal addition also follow different approaches from basic, neutral or acidic bath and metal addition 12-24 hours or even more after bath-up. Recently dry start-up has also been used. Early operation and the time to normal operation in general depends on cathode block grade and is from 2-3 weeks to three months. This paper will present different approaches to cell start-up and early operation through time and among companies.
2:30 PM
Direct and Indirect CO2 Equivalent Emissions from Primary Aluminium Production: Halvor Kvande1; Gudrun Saevarsdottir2; Barry Welch3; 1Norwegian University of Science & Technology; 2Reykjavik University; 3University of Auckland, Auckland, New Zealand, and University of New South Wales
The total global average emissions from primary aluminium production are large, about 16.5 tonnes of CO2 equivalents per tonne of aluminium produced (t CO2e/t Al). Two thirds of the total emissions arise from the source of energy used to generate electricity, because so much of the electricity for aluminium production comes from fossil sources like coal and natural gas. The present paper discusses the emissions from aluminium smelters, based on the requirement of the Aluminium Stewardship Initiative (ASI) that the on-site direct and indirect emissions from all present and future smelters shall be below 8 t CO2e/t Al by 2030 or earlier. Our suggestion is to use the total mine-to-metal emission number instead, thus referring to all aluminium production processes combined. This number is what the public, and also customers and downstream users, would be more interested in. The numerical value should be changed accordingly on a science based approach.
2:55 PM
Gas Recycling and Energy Recovery. Future Handling of Flue Gas from Aluminium Electrolysis Cells: Samuel Senanu1; Asbjørn Solheim1; Rune Lødeng1; 1SINTEF
Flue gas recycling and energy recovery provides an excellent opportunity for the aluminium industry to reduce the total energy consumption and to prepare for possible future carbon capture and storage or utilisation. Gas recycling enables increased CO2 concentration and more efficient recovery of heat from the flue gas. The present paper addresses some of the challenges with this technology, including increased concentrations of other pot gases such as CO, SO2 and HF and possible increased fugitive emissions due to reduced suction. Increased concentration of CO is particularly unwanted, since it is a lethal compound. Thus, catalytic conversion of CO to CO2 is crucial for HES reasons, and it also increases the amount of collectible heat. High concentration of SO2 can pose problems to equipment, including the heat exchanger units, due to the formation of sulfuric acid when the acid dew point is reached.
3:20 PM
The TMS Industrial Aluminum Electrolysis Course – History, Development of Contents, and Future: Halvor Kvande1; Stephen Lindsay2; Vinko Potocnik3; Alton Tabereaux4; Barry Welch5; Michel Reverdy; 1Norwegian University of Science & Technology; 2Hatch. Previously: Alcoa Inc.; 3Potocnik Consultant Inc.; 4Smelting Consultant; 5University of Auckland and University of New South Wales
The TMS Industrial Aluminum Electrolysis (IAE) Course on Theory and Practice has been held sixteen times in eight different countries in four continents since 1996. The location was always selected so that a visit to a near-by aluminum smelter was a part of the program of the course. The background and development of the course and its contents are presented here, and the experience and learning that the instructors have had during the work with these courses are described. It has been a popular course with an average of more than fifty participants. The success of this course has inspired TMS to organize a series of new courses related to aluminum production and developed expressly for the aluminum industry. Their main topics are anode technology, control of potline scrubber and fugitive emissions, and aluminum cast shop.
3:45 PM Panel Discussion