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

Wednesday, AM Room: B3

February 7, 1996 Location: Anaheim Convention Center

Session Chairperson: TBA

8:30 am

A MATHEMATICAL MODEL FOR ELECTRICAL ENERGY, HEAT TRANSFER AND FLUID FLOW IN FALCONBRIDGE'S SMELTING FURNACE: Y. Y. Sheng, Noranda Technology Centre, Pointe Claire, Quebec, H9R lG5, Canada; G. A. Irons, Department of Materials Science & Engineering, McMaster University, Hamilton, Ontario, L8S 4L7, Canada; D. G. Tisdale, Falconbridge Limited, Falconbridge, Ontario, POM 1 S0, Canada

Falconbridge smelts nickel calcine in a 36 MVA immersed arc smelting furnace. A three-dimensional model for the electrical energy dissipation, heat transfer and fluid flow in the matte and slag was developed. To validate the model, the voltage and temperature distribution were measured in the furnace. Analysis of the results revealed a significant voltage drop at the Soderberg electrode interface due to arcing. The implications for the operation of the furnace are discussed.

8:50 am

HIGH TEMPERATURE INTERACTION STUDIES TO SCREEN MELT CRUCIBLE MATERIALS FOR STANLESS STEEL-ZIRCONIUM ALLOYS AND URANIUM: Sean M. McDeavitt, Chemical Technology Division, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439; Garth W. Billings, Thermal Technology, Inc., 1911 Airport Blvd., Santa Rosa, CA 95403

Two important steps in the electrometallurgical treatment of spent nuclear fuel, as developed by Argonne National Laboratory, are the melt consolidation of stainless steel-zirconium (SS-Zr) alloys and of uranium. The SS-Zr alloys are generated as waste forms for the metallic cladding hulls and fission product metals. The uranium is collected as a dendritic mass and melted into a dense ingot. Both processes occur under a molten salt. Cold-crucible melting is not a viable option for either of these processes, so stable ceramic and coated materials are being evaluated as melt containment crucibles. Thermodynamic stability was used to select candidate compounds consisting of oxides, carbides, nitrides, borides and sulfides. Elevated temperature sessile drop experiments were performed using zirconium, SS-Zr alloys and uranium under inert as at temperatures up to ~2100, ~1900, and ~1600°C, respectively. The sessile drop experiments were observed and recorded in situ through an external video camera.

9:10 am

THE KINETICS OF SELENIUM REMOVAL FROM MOLTEN COPPER BY POWDER INJECTION: Y. F. Zhao, G A. Irons, Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario, L8S 4L7, Canada

The injection of reagent powders is a rapid means to remove impurities from copper. In this study, it was found that selenium and oxygen were simultaneously removed when sodium carbonate and calcium carbide were injected simultaneously into 70 kg heats of copper. A mathematical model was developed to describe diffusioncontrolled selenium and oxygen removal rates at calcium carbide particle interfaces. It was found that the utilization of the powder varied over a wide range, depending on the selenium and oxygen contents. The industrial implications of the work are discussed.

9:30 am BREAK

9:40 am

BARRIER REFACTORIES FOR ALUMINA REDUCTION CELLS: George Oprea, Clayburn Refractories Ltd., 33765 Pine Street, Abbotsford, B.C. Canada V2S 5C1

Several fireclay refractories, such as refractory bricks and dry-barrier powders were investigated using different testing procedures for their corrosion resistance to cryolite bath in oxidizing and reducing atmospheres. Although it is difficult to simulate in laboratory experiments the real conditions of an electrolytic cell, all test results verified a similar corrosion mechanism. Accordingly, the "barrier layer" the product of reaction of cryolite bath and refractory material, has multiple roles in the corrosion evolution. The chemical, mineralogical and thermal characteristics were investigated in order to estimate the life in service for a potlining refractory.

10:00 am

VSS CELL ELECTRIC, MAGNETIC AND HYDRODYNAMIC FIELDS DISTRIBUTION MODELLING: V. V. Ovchinnikov, O. G. Provorova, T. V. Piskazhova-Dept. of Higher Mathematics, Krasnoyarsk University, Russia; V. V. Pingin, D. A. Gorin, New Technologies and Equipment, Krasnoyarsk Aluminum Smelter, Russia; V. Y. Buzunov, Scientific & Technological Light Metals Center, Russia

The paper describes mathematical models of VSS cell electric, magnetic and hydrodynamic fields (Moro-Evance method). The computations were carried out using the following inputs: stud current distribution, collector bar current distribution, inducted B gradients along the cell perimeter. The models allow to develop a two-dimensional current density map of the anode, bath, metal, cathode bottom and also inducted B vectors in metal, metal flow patterns and metal-bath boundary contiguration. Based on experimental metal flow patterns data a method has been developed to determime a turbulent action coefficient used to compute the metal movement velocity. Computation results are shown for C-8bM cell deslgn.

10:20 am

INNOVATIVE EQUIPMENT TO DECOAT SCRAP ALUMINUM: Robert De Saro, Energy Research Company, 12 Dartmouth Road, Annandale, NJ 08801

Energy Research Co. (ERCo), the New York State Energy Research and Development Authority (NYSERDA), Roth Bros. Inc., Stein Atkinson Stordy (SAS), and O'Brien & Gerc are demonstrating a technology to decoat oily and painted scrap aluminum for the secondary and primary aluminum industries. Compared to conventional equipment this equipment, termed IDEX, reduces energy use, emissions, and dust formation, and increases production. The IDEX consists of a sealed rotating kiln, afterburner, and associated equipment. Scrap is fed into the kiln and the scrap oils or paint are vaporized by a 1500deg. counter-flowing gas stream. The gas stream has an oxygen level of 6-9% which prevents combustion from occurring in the kiln. The gas stream is then passed to an incinerator where the organics are incinerated apart from the scrap. An energy use reduction of 56% is possible. Additionally, there is a major reduction in emissions of VOC's, particulates, CO, Nox and CO₃, and a production increase due to the reduction in dross.