Aluminum Reduction Technology: Cell Operation (Performance and Operating Advances)
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Nadia Ahli, Emirates Global Aluminium; Nancy Holt, Hydro Aluminium As
Tuesday 8:30 AM
March 16, 2021
Room: RM 28
Location: TMS2021 Virtual
Session Chair: Nabeel Al Jallabi, ALBA; Nancy Holt, Hydro Aluminium As
8:30 AM
Carbon Dust - Its Short-Term Influence on Potroom Operations: Matthias Dechent1; 1Trimet Aluminium SE
Carbon dust refers to carbon particles, originating from carbon inputs into the smelting process like anodes, that float on top of the bath, below anodes or suspended in the bath. The phenomenon has a deleterious effect on the specific energy consumption of cells and can lead to anode deformations, hot cells out of the process window and stoppage of cells.Trials were conducted in the TRIMET Hamburg Smelter focusing on the effect of dust at anode changes. The conditions were chosen to be best and worst practice as assessed by a visual carbon dust assessment in the taphole. Contrasting with published literature, there was no relation in the experiments between spike formation and carbon dust in anodes after 8 hours. Anodes set in cells with a high carbon level in the taphole did not behave differently when compared to anodes with a low carbon dust content in the taphole. Samples obtained from the frozen bath layer underneath the anodes showed carbon contents in the range of 0.0315 to 6.29 %.
8:50 AM
Experience with Lengthy Pot Hibernation at Alcoa Baie-Comeau: Xiangwen Wang1; Marie-Eve Laframboise1; Patricia Gagnon1; Gilles Proulx1; 1Alcoa Corp
Two AP18 pots were put into sleep (hibernation state) from a normal production state. The pots were then maintained at the hibernation state for about 4 weeks. They were then woken up and successfully transitioned back to their normal operation. During the hibernation period, the pot was operated at the line current amperage and maintained around 840 to 860 degree C. This paper presents the pot thermal behavior and responses at different phases of the hibernation process from transitioning into a hibernation state, maintaining a stable sleep state, to waking up and transitioning back to a normal production state. Some special adjustments were necessary for each phase during the hibernation process. Interesting observations were made, some unanticipated events which had to be dealt with effective counter measures, are also presented and discussed.
9:10 AM
Improvement to Alpsys Instability and Alumina Feeding Control: Anne Gosselin1; 1Rio Tinto
Several changes during our latest increases of cell productivity had a significant impact on cell resistance behavior and general cell performance. Lower anode cathode distance operation and/or anode size enlargement have led to a significant drop in bath volume. At the same time, more alumina must be dissolved in a context of higher current density. Alumina dissolution and dispersion through the cell became an issue and the level of instability has risen. Along with increasing instability, mucky cells became more frequent. Changes in control algorithms were needed to face this new reality and bring back cell performance to its former level or even improve it. Instability procedure have been modernized in order to discriminate high and low frequency instabilities. Alumina feeding procedure needed to be more robust against instability and be independent from instability procedure. Results from implementation at Alma plant are presented.
9:30 AM
Hydro’s New Karmøy Technology Pilot: Start-up and Early Operation: Pierre Reny1; Martin Segatz1; Haakon Haakonsen1; Håvard Gikling1; Mona Assadian1; Jan Frode Høines1; Espen Kvilhaug1; Asgeir Bardal1; Erik Solbu1; 1Hydro
After the successful development and operation of the 6 HAL4e test cells at its Årdal research Center starting in 2008, Hydro decided in 2015 to build an industrial pilot plant. The site chosen is on Karmøy island in Norway, on the very same, cleaned site where the Karmøy Søderberg plant once operated. The 60-cells plant is called the Karmøy Technology Pilot, or KTP for short. The HAL4e cell development program’s ambition included step improvements in energy consumption and environmental friendliness. These innovations span many aspects of cell technology, environment protection, infrastructure and operation, like low cell resistivity, PAH-free linings, low energy cell preheat and start-up, low specific energy consumption, low anode effect rate and duration, low fluoride emissions, low CO2 emissions, automated cell operations and many more.This paper summarizes the preparation and start-up activities and also presents operating results of the first two years of operation.
9:50 AM
AP12 Low Energy Technology at ALRO Smelter: Marian Cilianu1; Bertrand Allano2; Gheorghe Dobra1; Ion Mihaescu1; Claude Ritter2; Andre Auge2; Yves Caratini2; 1Vimetco alro; 2Rio Tinto
Electricity cost is the main differentiator of the competitive structure of an aluminum smelter. Over the last few years, ALRO Group, the biggest industrial power consumer in Romania, delivered ambitious projects to lower specific energy consumption. To reach the next level, in 2018, ALRO mandated Rio Tinto Aluminium Pechiney (RTAP) for the supply of an AP12 Low Energy technology. To guarantee smooth technology transfer and achieve step change performance the AP Technology™ standard “cell development cycle” approach has been used. ALRO and RTAP worked together as a team to execute specific activities such as measurement campaign, modelling, risk analysis, readiness assessment, onsite and remote support, data analytics, go-no go, etc. This article presents this project that achieved step change reduction in specific energy consumption along with some supporting activities and tools.
10:10 AM Question and Answer Period