Conference Agenda

Ørsted in 1825 and Wöhler in 1827 are credited with discovery of aluminium, which they obtained from aluminium chloride, the former in reaction with potassium amalgam, and the latter with pure potassium: Al2 Cl3 +3KAl+3KCl. Initially, both likely obtained an aluminium alloy with some potassium. In 1827, Wöhler obtained aluminium powder, but continued his research, and in 1845 was able to produce small pieces of the metal and described some of its physical properties. For this, he is credited with the first isolation of the metal in pure form.

The aluminium discovery initiated an aluminium hype and people from all over the world came to Göttingen, including the Frenchman Saint-Claire Deville and Frank Jewett from USA. Jewett motivated his student Charles M. Hall to develop a process for industrial production of aluminium. In Wöhler’s Institute worked Alfred Wilm. He developed the age hardening of aluminium alloys and made aluminium a versatile material suitable to build planes.

Bunsen obtained in 1854 aluminium in an electrolytic process with the power source of the "Bunsen Element". Industrial production of aluminium by electrolysis was not possible until after Siemens found in 1866 the electrodynamic process for continuous generation of electricity. But Bunsen had already focussed on competitive alumina production. Two of his Heidelberg students were successful. Georg Otto Giulini and Karl Josef Bayer were able to digest bauxite in liquid potassium at a very cost competitive basis. Bayer later used sodium hydroxide (caustic soda) for alumina production and this is known as Bayer process. Bielfeldt in 1966 invented the operation of the tube digestion process for high pressure, high temperature digestion of monohydrate bauxites. The Bayer process in combination with the Hall-Héroult process enabled the industrial production of aluminium in a competitive way-till now.

In more recent history since 1960s, Germany contributed to the development of Hall-Héroult cell technologies, smelter modernisation and most recently flexible power usage, continuous prebake anode, anode paste mixers, carbon baking furnaces, cathode block production, and alumina transport systems to the potlines.

In 1936, Roth developed a water-cooled mould to cast rolling slabs and extrusion billets. Now RIA Casthouse Engineering produces most advanced furnace charging and skimming machines as well as in-furnace dross recovery of aluminium.

Due to high expected power prices, TRIMET Aluminium SE started to reduce the production output in its three German electrolysis sites by around 20 % in 2021. After the start of the war in Ukraine and subsequent gas pipeline explosions in 2022, the German smelters curtailed its production and operated at only 30 % of its capacity. The F-Line in Saint-Jean-de-Maurienne was also curtailed in 2022 due to limited energy availability in France.

To restart the idled potlines with a common best practice, as soon as prices and energy availability would allow, a joined meeting was conducted already in the beginning of 2023, to discuss methodologies, equipment, and team organisation. The teams from the four smelters discussed past experiences and shared concerns about safety and limiting factors for restarts, for example liquid bath generation.

The preparation process and its results are presented in this paper as well as experiences of failed tests, and incidents during restart operations. The four smelters started the ramp-up in the first quarter of 2024 and the results from the first months in the restart environment are discussed.

Rio Tinto Kitimat Aluminium Smelter uses AP40 technology with 8 sections of 48 pots in a single potline. In this type of configuration, continuity in alumina supply is crucial for operating the smelter smoothly. Rare cases of alumina supply interruption can disrupt a smelter operating at full capacity over a long period. The 1000-South Section suffered a hyper-dense phase system failure on 9 November 2022, causing 48 pots to lose alumina supply suddenly. Initially, the maintenance diagnosis assumed no foreseeable recovery before 72 hours. A contingency plan was activated, keeping the pots in sleeping mode for a few days by lowering the anode beam such that no electrolysis happens. In the meantime, limited information exists on alumina disruption and use of the sleeping mode on a full section. This paper summarises the successful process steps in Kitimat that prevented pot loss by employing the sleeping mode. Methods, lessons learned, and further initiatives are discussed.

EGA has extensive experience in brownfield modernization of its technologies, with D18+ and D20+ cell designs successfully developed to replace the old D18 and CD20/D20 technologies at EGA Jebel Ali. In June 2020, EGA and INALUM entered into a Technology License Agreement to enhance the performance of INALUM S170 Sumitomo technology cells at the Kuala Tanjung smelter. The collaboration aimed to use EGA's expertise to increase metal production at the INALUM smelter. The initial phase involved upgrading five pilot cells in a boosted section of Potline 1 to operate at an increased amperage of 215 kA, 20 kA above the nominal 195 kA. This upgrade represents the first brownfield modernization project outside EGA.

This paper focuses on detailed modelling studies assessing the electrical and heat balance, magnetic field, magneto-hydrodynamics (MHD), and the integrity of the cathode lining and potshell. It also covers engineering work to modify the superstructure for conversion from centre-break feeding to point feeding, and the implementation of a new EGA pot control system. The studies led to recommendations for improved lining and potshell design, a superstructure with the new feeding system, and minor busbar modifications aimed at a 20 kA amperage increase and reduced specific energy consumption. Modelling and engineering studies were also required for the design of the pilot booster section. The enhancements in design and pot control logic were pivotal for achieving and exceeding the project's contractual Key Performance Indicators (KPIs). The Performance Test showed that at the target amperage of 215 kA, the daily metal production exceeded the target by 22 kg per cell. This paper provides insights into the methodologies and challenges encountered in the design improvement process, contributing to the successful commissioning and operation of the upgraded cells.