Steel symposium examines ladle refining/reheating.

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Steel foundries have realized the need to extend their secondary ladle refining practices in order to improve quality and productivity, increase flexibility in their melting and casting operations and reduce steel production costs.

Earlier this year, 40 industry representatives from 13 states attended a symposium to examine the potential of new ladle reheating/refining technologies for steel foundries and small (6-8 ton heat size) producers. Symposium sponsors included; AGA Gas, Air Products and Chemicals, ABB Industrial Systems, Consolidated Natural Gas, FOSECO, JSG Technical Services, Leybold Technologies and The Peoples Natural Gas Company. AIM Resources was the principal coordinator.

Opening remarks pointed to the problem steel foundries have in making use of ladle reheating and refining technologies that also address their technical and economic needs. Steel foundries are faced with problems similar to those experienced in basic steel production: trying to efficiently meet more stringent quality requirements. Peter F. Wieser, Wieser & Associates, reviewed the technical reasons for refining steel, basing them on improving product quality and overcoming obstacles to quality control through the use of refining technology. Specific analyses were presented for electric arc and electric induction melting.

Ladle refining furnaces have become essential elements in basic steel production. They offer greater flexibility for optimizing production schedules, increasing productivity, reducing processing costs and improving quality. J. Kevin Cotchin, Lectromelt Corporation, discussed the basics of ladle metallurgy as they apply to the foundry. Included are slag-free tapping, gas stirring, ladle refractory selection, and the more complex reheating and degassing technologies. Cotchin reviewed operating data from ladle metallurgy installations, including examples of foundry-size installations, and he explored the implications in the data as related to small heat ladle metallurgy facilities.

Natural and industrial Gases

Bob Brandt of East Ohio Gas provided a gas industry perspective using examples of commercial usage of natural gas in steelmaking shops. He included electric arc furnace, ladle preheating and oxygen melting of steel scrap to demonstrate how oxygen technology can be used to preheat as well as melt steel scrap. Natural gas can be a low cost alternate source of energy for ladle preheating and molten steel reheating, he said

Lars Frisk, AGA, presented information on ladle-related technologies for steel foundries based on the use of industrial gases. Two different technologies were reviewed. One method seeks to minimize the temperature drop when transferring from the melting furnace to the ladle. The other is designed to either maintain metal temperature or to heat the melt in the ladle.

Bob Best, Air Products, presented information about Reactive Element Heating (Reheating). Reheating utilizes a metallic fuel (aluminum or silicon) and a novel submerged oxygen injection technique to reheat molten steel in the ladle.

A Case Study

The symposium's keynote speaker was Clyde Smith, vice president/technology for Johnstown Corp., who spoke on "Adapting a Ladle Furnace to a Steel Foundry." Johnstown is one of the few steel foundries using ladle reheating. He described what was done to satisfy the need to have relatively large quantities of liquid metal available to pour large steel castings and rolls and explained how ladle reheating was accomplished. He also listed approximate costs and related some operating experiences.

Electrotechnologies

Electrotechnoiogies offer another alternative for reheating, according to Ralph Perkul, ABB, who reviewed the newest technology for melting in coreless induction furnaces, charge makeup and auxiliary systems. In addition, he reviewed the latest in refining and pouring techniques, including the Calidus System, vacuum cap and inert gas furnaces.

Wilfried R. Zenker of Leybold Technologies, Inc. discussed new vacuum melting refining concepts: vacuum induction degassing and pouring (VIDP) and vacuum induction degassing (VID). These concepts were developed from vacuum induction melting technology and are applicable for the production of very clean metals in batch sizes from 1-20 tons.

Ladle Linings

Alternative technologies to reheating to improve temperature control were reviewed. One such technology is the use of cold ladle linings. Brian Alquist of FOSECO spoke of the potential benefits of cold ladle lining systems in coreless induction furnaces. He said that these systems provide an opportunity for flexible and efficient use of the furnace and, ultimately, a reduction of inclusions compared to conventional refractory inner linings.

Facilities Engineering 

Equipment isn't the only issue in adapting ladle reheating to a melt shop. Engineering the melt shop facility to adapt a new ladle reheating technology requires specialized knowledge and experience. John Bassano, JSG Technical Services, Inc., reviewed the factors that need to be considered in adapting a ladle furnace to a foundry meltshop. These include: layout, impact on other processes, auxiliaries, environmental and other issues such as ladle preheating, weighing, gas purging of the ladle and shrouding of pour streams.

AIM Resources is planning another symposium in the fall of 1991. Those interested in the next symposium or in obtaining symposium proceedings should contact: Alternative Industrial Marketing (AIM) Resources, P.O. Box 101086, Pittsburgh, PA 15237; 412/3667778; fax: [phone].

AIM Resources specializes in market research and development in the Us steel industry.