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About the 1996 TMS Annual Meeting: Wednesday Morning Sessions (February 7)

February 4-8 · 1996 TMS ANNUAL MEETING ·  Anaheim, California

CARBON TECHNOLOGY III: Anode Quality Control

Proceedings Info

Sponsored by: LMD Aluminum Committee

Program Organizer: Lise Castonguay, Alcan International Ltd., Arvida Research and Development Centre, P.O. Box 1250, 1955 Mellon Blvd, Jonquière, Québec, Canada, G7S 4K8

Wednesday, AM Room: A7

February 7, 1996 Location: Anaheim Convention Center

Session Chairperson: Mr. Berthold Hohl, Maschinenfabrik Gustav Eirich, Walldürner Strae 50, D-74736 Hardheim, Germany

8:30 am

A METHOD FOR CHARACTERIZATION OF ANODE PORE STRUCTURE BY IMAGE ANALYSIS: S. Rorvik, H. A. Oye, Institute of Inorganic Chemistry, Norvegian Institute of Technology, University of Trondheim, N-7034 Trondheim, Norway

A fully automatic method for image analysis of porosity in baked carbon anodes has been developed. The method is based on optical microscopy, and is capable of analysing large sample areas (several cm2). It provides various statistics of pores in the range of 10 um to 10 mm radius. In addition to standard measurements like pore size distribution, some alternative techniques have been used to give information on how the pores are positioned relative to each other. These techniques include determination of the fractal dimension of the pore surface, the degree of pore clustering, and the degree of pore connection. The results from application of the present method point to the importance of using additional ways to characterize pore structure; the pore size distribution alone does not provide sufficient information to explain variation in anode physical properties such as permeability and electrical resistance.

9:00 am

REDUCTION OF AHEAD OF SCHEDULE ANODES THROUGH ANODE ROD QUALITY CONTROL: Yvon Ménard, François Baillargeon, Alcan Smelters and Chemicals Ltd., Grande-Baie Plant, 6000, 6th Avenue, P.O. Box 900, La Baie, Québec, Canada, G7B 4G9; André L. Proulx, Claude Perron, Alcan International Ltd., Arvida Research & Development Centre, 1955 Mellon Blvd, P.O. Box 1250, Jonquière, Québec, Canada, G7S 4K8

One of the major causes of ahead of schedule anodes reported in recent years by P155 potroom operation was related to an inherent weakness in the rod welded joints. The development and implementation of an apparatus and a procedure to measure, detect and reject the faulty rods prior to anode rodding, will be presented and discussed. The technology has not only significantly reduced the number of ahead of schedule anodes, it has also provided useful information concerning other process improvements.

9:20 am

METHODS OF VERIFYING NET CARBON: Marilou McClung, Ravenswood Aluminum, P.O. Box 98, Ravenswood, WV 26164

Problems currently exist with using net carbon as an industrial standard to gauge smelter performance. First, throughout the industry there are a number of different methods used for determining net carbon. Also, until recently there has not been a viable method to cross check or predict change in net carbon. This inherently leads to differences and most likely inaccuracies when comparing performances of different plants using a net carbon number. Ravenswood uses specific methods when calculating the net carbon balance. The R&D Carbon, Ltd. formula developed by Verner Fischer, et al., to predict and cross check net carbon based on baked carbon core analysis has also been successfully used. Another method is used, as a cross check, which is based on the raw materials (cokes and pitch) usage as related to the metal produced. The combination of these methods gives a definitive representation of the carbon performance in the reduction cell. This report details the methods Ravenswood Aluminum uses and the information derived from it.

9:40 am

IN-LINE INSPECTION OF CARBON ANODES FOR USE IN ALUMINUM PRODUCTION: Fawzi Emad, Paul Haldemann, Electrical Engineering Department, University of Maryland, College Park, MD 20742; Art Nispel, Eastalco, 5601 Manor Woods Road, Frederik, MD 21701; Larry Logan, Formerly with Eastalco, now at C&K Publications, PO Box 340, Hancock, MD 21750

In this paper, methods of measuring the quality of carbon anodes which are produced and continually consumed in the commercial production of aluminum are discussed. The electrical and mechanical properties of these anodes are very important for the economic operation of the aluminum plant. At least six different ways of checking some of the most important anode characteristics were investigated and those methods selected as the most suitable for testing the quality of the anodes are elaborated. Results from tests made at the plant are included. Future work planned in this area is also discussed. The methods considered include: 1. Direct resistivity measurement using core samples; 2. Ultrasonic measurement; 3. Hammer method; 4. Hall effect; 5. 4-probe method; 6. Magnetic coils (various arrangements). It will be shown that some of these methods give inaccurate results while others are not practical due to operating conditions and/or production parameters.

10:00 am BREAK

10:20 am

STANDARDIZATION OF METHODS FOR TESTING CARBONACEOUS MATERIAL FOR THE PRODUCTION OF ALUMINIUM: Wolfgang Schmidt-Hatting, International Standardization, Taeusistrasse 48, CH-8630 Rueti (ZH), Switzerland

When determining whether material conforms to specifications the mean value of the property under test must be compared to upper and lower limits. In order to do this comparison, standardized test methods including precision (repeatability and reproducibility) figures must be available. Since 1973, many standards prepared by the ISO Subcommittee 7 of the ISO Technical Committee 47 (chemistry) have been published. A large number of methods are being prepared for publication as a standard. The work program of subcommittee 7 will be presented. A close cooperation between ISO and ASTM has been established to aim for universally valid Standards on the American continent and worldwide. The so-called Vienna Agreement makes it possible for ISO standards to become directly CEN (European) Standards. Therefore, active participation in ISO seems to be essential for industrialized countries.

10:40 am

TOTAL QUALITY MANAGEMENT: HOLISTIC APPROACH AT THE ALUCHEMIE CARBON ANODE PLANT: Jan Engels, Ton Halsema, Aluchemie, Oude Maasweg 80, 3197 KJ Botlek-Rotterdam, The Netherlands

In June 1991, Ton Halsema, general manager of Aluchemie Rotterdam, introduced Total Quality Management (TQM) at the Aluchemie carbon anode plant. First a new business plan (1991 - 1996) was made and discussed. Then the Total Quality Program was introduced in February 1992. Since 1992, the implementation of TQM at Aluchemie has by its holistic approach radically changed the bottom line results, as shown by some examples of 1994 results against those of 1991: 15% less labour hours per ton produced, 60% less Nett Working Capital, 40% less absenteeism due to illness. Most of the results have been reached by systematic approach. The crux of the holistic approach is the recognition of the existing links between <<the company's strategy, its structure and culture>>. Progress in achieving TQM is measured against the criteria of the European Quality Award. These criteria, which build up TQM, help to structure the business, to measure it and to manage it for better results.

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