Electromagnetic Flow Control of Molten Metals for American Iron and Steel Institute and the Department of Energy.

Sponsored by the American Iron and Steel Institute and the Department of Energy, Concept Engineering Group Inc. is developing MAG-GATETM, an electromagnetic system for active molten metal flow control. Today, nearly all of the world’s yearly steel production, approximately 700 million tons, is by continuous casting. The American steel industry produces approximately 100 million tons of steel annually valued at close to $50 billion. The maturing of continuous casting in the US, the emphasis on “clean steel,” the rise of ladle and tundish metallurgy, the trend to higher production machines, and the need for precise control in innovative casting processes have all increased the importance of flow control in modern continuous casting. The Steel Manufactures Association and the American Iron and Steel Institute have recognized this need for improved active flow control as part of their Steel Industry Technology Roadmap.In a modern steel continuous caster, control of the flow of the molten metal from the tundish to the mold is the critical location. The electromagnetic flow control is expected to improve performance over the current state of the art in the following ways:
  • Provides independent control over the casting rate to meet tight specifications on the heat removal rates in all commercial grades.
  • Provides a greater degree of control over that of changing the tundish level height.
  • Offers independent flow control on each nozzle to compensate for uneven nozzle wear or clogging among the multiple strands in a caster fed from the same tundish.
  • Gives the operator the capability to adjust flow independent of strand motion changes to maintain a constant mold level height, which is so important to good quality.
  • Opens up markets currently not available to the minimills with the ability to counter the traditional nozzle blockage problem of aluminum-killed steels via the controlled flow and heat addition capabilities.
  • Regulates flow without introducing stream roughness and the subsequent mold turbulence, reoxidation, and impurity entrapment.
  • Eliminate sites where stream velocity changes abruptly, which then causes inclusions to accumulate.
  • Eliminates the mechanisms needed to move a stopper rod or slide-gate plates which are subject to, wear and failure.
  • Electromagnetically improves the steadiness of the pouring stream eliminating turbulence from the ladle stream and the tundish resulting in improved quality.
  • Gives a greater capacity to deal properly with hot or cold heats.
  • With the trend toward larger tundishes, provides a new capability to offset the extra head present with the greater depth that is desired to minimize vortexing and to maximize inclusion float.
  • Allows a higher number of sequential casts through increased nozzle reliability and performance, which results directly in higher productivity.
Two successful prototype tests with hot metal have been performed at the Whemco Foundry Division, Midland, PA. Approximately 110,000 pounds of 0.2% carbon steel were poured through the device subject to electromagnetic flow control. A very smooth steel stream was achieved. Temperatures of the device surrounding the molten steel were stable and extremely good cooling of the electric coils was achieved. Excellent agreement was seen between expected theoretical performance and actual test results. A full report can be found at the AISI web site www.steel-trp.org.
Test Stand during pouring trials at Whemco Foundry, Midland PA.

Prototype Mag-GateTM device installed on tundish.

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