Sponsored by: LMD Aluminum Committee
Program Organizer: Julian V. Copenhaver, Technical/Quality Manager, NSA A Division of Southwire, PO Box 500, Hawesville, KY 42348
Tuesday, PM Room: A10
February 6, 1996 Location: Anaheim Convention Center
Session Co-Chairpersons: Dr. Diran Apelian, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280; Mr. Jerry Dassel, Commonwealth Aluminum Company, PO Box 480, Lewisport, KY 42351
SAMPLING OF ALUMINIUM MELTS AND DETECTION OF NON-METALLIC INCLUSIONS USING LAIS: D. Sampath, P. G. J. Flick, J. Pool, W. Boender and W. van Rijswijk, Corporate Research Laboratory, Hoogovens Groep BV, PO Box 10,000, 1970 CA IJmuiden, The Netherlands
The compelling needs to qualitatively/quantitatively monitor the inclusion content of aluminium melts led to the development and use of several inclusion assessment methods. The requirement to quantify the inclusion content arises from the adverse effects of non-metallic inclusions on the product quality of aluminium alloys. Simplicity coupled with ease of transport caused the LAIS method to be one of the preferred techniques to measure the inclusion contents. Several sampling trials were conducted with the LAIS method. An optimized sampling procedure was developed. The sampling time is primarily influenced by a combination of melt inclusion content and temperature. By examining the LAIS samples, different types of non-metallic inclusions present in production melts have been identified and will be presented.
A STUDY OF THE ROLE OF PARTICLE CONCENTRATION AND FLUID VELOCITY ON DEEP BED FILTRATION BEHAVIOUR: F. Andrés Acosta-González, E. Ruiz A., A. H. Castillejos E., M Méndez N., J. C. Escobedo B., CINVESTAV Unidad Saltillo, Apdo. Postal 663, 25000 Saltillo, Coahuila, Mexico In this work, a physical model of interconnected cells of ceramic foam filters is used to visualize the role of particle concentration and fluid velocity on deep bed filtration behaviour. The design of this model is based on the Reynolds number, the Gravity number, and the ratio of the particle diameter to the cell diameter. It was found that the values for these dimensionless numbers for molten aluminum flowing at typical superficial velocities between 1-3 cm/s through ceramic foam filters, having a pore diameter between 1-3 mm, are similar to those obtained in a physical model consisting of a viscous glycerol-water mixture carrying bakelite or pliolite particles through several interconnected void glass spheres. These spheres are 2.54 cm inner diameter, and the whole set of spheres is submerged in a transparent container filled with the liquid. In this way, refraction of light and lateral fluid flow are minimized. The observations were registered and analyzed using a high speed camera interfaced to a motion analysis system. It was found that at a high enough fluid velocity, flow recirculation occurs in the pores. Under this situation, it could be expected that the probability of particle attachment on the filter walls would increase. Also, a high particle concentration induces collisions among the particles, which results in changes of their original trajectories. The observations indicate that the perturbation enhances the probability of particle retention inside the filter cells.
EVALUATION OF A BONDED PARTICLE CARTRIDGE FILTRATION SYSTEM: Dr. Wolfgang Schneider, Dr. H. P. Krug, V.A.W. Vereinigte Aluminium Werke AG, Georg-Von-Boeselager-Strasse, 25D-5300 Bonn, Germany; V. Dopp, Foseco G.m.b.H., Postfach 1220, D-4280 Borken, Germany; Dr. N. J. Keegan, M. D. Bryant, Foseco Internaional Limited, 285 Long Acre, Nechells, Birmingham, England B7 5JR
Metal cleanliness is a major issue in today's aluminium casthouse, especially in the production of critical products such as canstock, litho sheet and foil. Bonded particle cartridge filters are widely regarded as the most effective means available for inclusion removal from critical production items. V.A.W. and Foseco have carried out a joint programme of evaluation of a Metaullics 14 tube cartridge filter system in conjunction with ceramic foam filters and an in-line degassing unit in various configurations. The ceramic foam filters ranged from standard, coarse pore types to new generation all-ceramic bonded, fine pore types. Metal cleanliness was assessed using LiMCA, PoDFA, and LAIS sampling techniques, as well as metallographic and scanning electron microscope examinations. This paper outlines the findings of this work which was carried out a V.A.W.'s full scale experimental D.C. slab casting unit as Neuss in Germany.
THE FILTRATION OF MOLTEN 1XXX SERIES ALUMINUM ALLOYS WITH RIGID MEDIA TUBE FILTER: K. Hoshino, T. Nishizaka, Mitsui Mining & Smelting Company Ltd., Corporate R & D Center, 1333-2 Haraichi, Ageo-shi Saitama 362, Japan; T. Yoshida, K. Kakimoto, Mitsui Mining & Smelting Company Ltd., TKR Division, 2-26-6 Higashinihonbashi, Chuo-ku Tokyo 103, Japan
Recently it has been increasing that molten 1XXX series aluminum alloys are filtered by Rigid Media tube Filters (RMF). In that case, it occasionally happens that the pressure drop across the RMF rapidly increases in relatively early stage. We have investigated inclusions captured in the RMF and conducted some model tests to clear up the cause. Consequently, the mechanism of the rapid increase of pressure drop is given.
3:20 pm BREAK
LIQUID METAL FILTRATION AND DISTRIBUTION USING FIBERGLASS FABRIC: C. Brochu, Alcan International Ltd., PO Box 1250, Jonquiere, Québec, Canada G7X 4K8; R. Dault, J. Déry, Pyrotek Incorporated, 2400 Boulevard Lemire, Drummondville, Québec, Canada J2B 6X9; Sylvain P. Tremblay, Pyrotek Incorporated, 1623 Manic, Chicoutimi, Québec, Canada G7K 1G8 In the last decade, the aluminum industry has mainly focused on improving metal quality by working on furnace and casting practices and especially on in-line treatment units. Fiberglass fabric is widely used throughout the industry, being often the last tool before the mold; and in this respect, few efforts have been reported to better understand or use fiberglass fabric in molten aluminum filtration and distribution applications. This paper will review the fiberglass fabric options. The different fiberglass fabric coatings and finishes will be described, as well as their properties and characteristics versus molten aluminum. Fiberglass fabrics use in filtration applications will be defined in function of selected parameters such as opening, finish, throughput, etc. Finally, the metal distribution will be discussed. A better understanding of the fiberglass fabric finishes and bag configuration improve the metal distribution and, ultimately, the final ingot quality.
IMPROVED EXTRUSION BILLET PRODUCTIVITY AND QUALITY USING A DUAL STAGE CERAMIC FOAM FILTRATION SYSTEM: Leonard S. Aubrey, Michael A. Cummings, Clifton L. Oliver, SELEE Corporation, 700 Shepherd Street, Hendersonville, North Carolina 28792, Mitch M. Chow, El Campo Aluminum Company, Route 3, El Campo, TX 77437
The presence of non-metallic inclusions in aluminum extrusion billets can significantly affect both plastic deformation during the extrusion process and final surface quality. Traditionally, secondary extrusion billet casters have relied on a combination of furnace fluxing and a ceramic foam filter to obtain the required melt cleanliness. With increasing quality demands on extrusion billet quality to obtain better surface quality and more complex shapes, as well as reduced press cycle times, there has been a trend towards the use of finer pore ceramic foam filters. The use of finer pore size ceramic foam filters (> 30ppi) generally requires the use of an expensive in-line spinning nozzle degasser system. Secondary billet casters often do not have the floor space for an in-line system. In addition, the efficient utilization of an in-line system requires the use of chlorine, which is coming under increasing restrictions. A novel two-stage filter bowl and preheat system has been developed to allow the use of 50 ppi ceramic foam filters without the use of an in-line spinning nozzle degasser system. Improved metal cleanliness was quantified by taking LAIS inclusion samples prior to and after the installation of a dual stage filtration system utilizing a combination of 30 and 50 ppi filters compared to an existing 30 ppi filter. Statistical analysis of press cycle times indicated an overall reduction of 11.4%.
EXPERIENCE OF ALCOA--KÖFEM WITH MHD INDUCTION STIRRER: Sandor Petho, Ingot Business Unit Engineering Manager, ALCOAKÖFEM KFT., H-8200 Szekesfehervar, Verseci u. 1-15, PO Box 102, Hungary
1) Operating principle. 2) Description of the equipment. 3) Working experience (7 furnaces). 3.1) Application of MHD. 3.2) Effect on heal melting process: Melting rate, productivity. Fuel consumption, Dross generation, Dross skimming, Temperature homogeneity, Chemical homogeneity (Forced metal tapping as a chance.) 3.3) Experience on maintenance. 4) Conclusion.
SIDE MOUNTED EMS FOR ALUMINIUM SCRAP MELTERS: Magnus Eidem, Göte Tallbäck, ABB Industrial Systems AB, Dept: HS, S-721 67 Västerås, Sweden; Patrick J. Hanley, ABB Industrial Systems, Incorporated, Metals Division, 100 Madison Corporate Park, Route 6, Brewster, NY 10509
Normally the electromagnetic stirrer (EMS) is placed below the furnace. However, it has recently been found that the EMS can also be placed at the side of the furnace, still giving good stirring. This makes it possible to install EMS on most existing furnaces. The side-mounted EMS is compared with the standard bottom-mounted stirrer with respect to installation, melting time, and flow pattern in the melt. The major conclusion is that a side-mounted EMS is practical and will give about as good a performance as the bottom-mounted. Melting time estimates are based upon 3-D fluid flow and hat transfer predictions in combination with a simplified scrap melting theory. Predicted melting times are in fair agreement with operational data for non-stirred and electromagnetically bottom-stirred furnaces.
A NEW ELECTROMAGNETIC CIRCULATION PUMP FOR ALUMINUM REVERBERATORY FURNACES: Dr. Richard S. Henderson, Director of Technology, Richard C. Chandler, President, Metaullics Systems Company L.P., 31935 Aurora Road, Solon, Ohio 44139; Warwick Brown, Director, EMP Technologies, Repton Road, Willington, Derby, DE65 6BX, England
The benefits of circulating molten metal in an aluminum reverberatory furnace
are well documented, and include higher productivity, reduced fuel consumption,
and excellent metallurgical and temperature homogeneity. Current methods to
achieve circulation or metal movement include mechanical pumps, electromagnetic
stirrers, and porous plugs. Each of these methods has limitations or drawbacks
which can be overcome by the use of an electromagnetic pump of novel design.
This new device was developed by EMPT, a UK company, and is marketed in North
America by Metaullics Systems Company L.P. It combines high pumping rates with
long-term reliability and realistic cost of purchase, installation and
operation. In addition, it can be readily retrofitted to existing open-well or
direct charge aluminum reverberatory furnaces. The EMPT pump has been installed
in 6 furnaces in the UK and France over a two-year period. The design and
operation of the electromagnetic pumping system will be presented with
performance data including melt rates, metal homogeneity and temperature
profiles. In addition, a video will be shown of the system processing a variety
of scrap feeds. Finally, procedures and costs for accomplishing a retrofit to
an existing furnace will be outlined.
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