This multimedia presentation is a component of the August 2000 (vol.52, no.8) JOM. To best experience this presentation, you should employ the latest version of RealPlayer. As the audio plays, images from the presentation will automatically load in the window to the right.
	The following article appears as part of JOM-e, 52 (8) (2000), http://www.tms.org/pubs/journals/JOM/0008/Welch/Welch-0008.html JOM is a publication of The Minerals, Metals & Materials Society

2000 Aluminum Plenary Session: Overview

Advancing the Hall Heroult Electrolytic Process

Barry J. Welch

Editor's Note: During the 2000 TMS Annual Meeting, the TMS Light Metals Division broke with tradition by striking all of the Monday morning sessions from its traditional programming grid in favor of presenting an all-division plenary plenary session. The goal of this session was to provide insight into critical issues in modern aluminum processing technology and industrial development. In further striking from tradition, the proceedings from that symposium are not available in print format. Instead, they are archived here in Real Audio format. Select the part of this presentation that you wish to view from the table to the right. Then, just click on the play button that will appear to hear the speaker and watch as the overheads from the presentation automatically click by in the right frame. The session was organized and moderated by Ray Peterson of IMCO Recycling. More detail, and other papers from this symposium, may be experienced by visiting the August issue's table of contents.

The design and operating advances achieved in the last quarter century will ensure the Hall Heroult technology will maintain a competitive advantage over alternative aluminum production processes for some time into the future. The advantages were lead by magnetic compensation and computerized process control coupled with electrolyte optimization. These enable larger more economic cells to be designed. During the same time, fundamental studies have enabled a better understanding of the subtleties of the processes and secondary reactions that were ignored in the theoretical understanding whilst the cells performed poorly. These secondary processes, including reactions associated with impurities and anodes consumption, those leading to onset of anode effect, and alumina dissolution kinetic have not been fully exploited yet. Today, as the focus shifts to higher productivity, the dynamics of the cell and the impact operations have on the very finely tuned heat balance becomes more important. With the high current efficiencies and low margins for error in modern cells the present challenge is to refine designs, control strategy and operating practices so that further marginal gain and economic performance can be achieved. This will include better management of aluminum fluoride, prevention of anode effects, and earlier detection of the increasingly prevalent anode spikes. Super structure design changes coupled with improved control and practice will also enhance productivity of future generations of cells.

ABOUT THE AUTHOR

Barry J. Welch, is a Professor at the Department of Chemical & Materials Engineering at The University of Auckland.