Die Entwicklung eines neuen Sauerstoffblaselanzenkopfes für den LD- Konverter mit Verwendung keramischer Werkstoffe

Translated title of the contribution: Development of a newly designed oxygen-blowing lance head for LD converters using ceramic materials

Marinko Lekic-Ninic

Research output: ThesisDoctoral Thesis

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Abstract

This thesis describes the development of a newly designed oxygen-blowing lance head for LD converters using ceramic materials. In an LD process oxygen is blown in iron melt through nozzles in an extendable water-cooled oxygen lance. The front end of the oxygen lance, the oxygen-blowing lance head, is exposed to severe chemical, thermic and mechanical stress. This severe stress causes wearing of soft and relatively low-melting-point cooper, especially of the round edges of the nozzle exit openings, what leads to the unwanted changes of the oxygen flow conditions in the entire steelmaking process. The first part of the thesis gives an overview and discussion of the state-of-the-art of the oxygen steelmaking and discusses the known problems in the LD process and in the existing lance systems. It has been concluded that there are significant misconceptions about the actual conditions in converters and their subsequent impact on oxygen-blowing lance heads. Hence, using the existing literature as the basis, an analysis of stresses to which a lance head is exposed has been conducted as accurately as possible. Furthermore it has been established that the process-dependent varying pressure conditions in converter disturb the projected flow of oxygen in nozzle, what results in the well-known abrasion of the nozzle edges. These findings have led to the idea to stabilize the oxygen flow conditions in nozzle. The effects of this approach have been confirmed experimentally. Different ceramic materials to be used in the new design of the lance head have been analyzed, tested and selected on the basis of these findings and other predefined criteria. Furthermore, a prototype of the newly designed lance head has been tested and analyzed in a laboratory converter. The results of the conducted laboratory tests were promising. The following tests were conducted in an experimental surrounding similar to the LD process. The results of these tests confirmed the feasibility of the new lance head design using ceramic materials. However, before any industrial application of the new lance head it would be necessary to optimize its design and to pursue additional long-term endurance tests under realistic operating conditions.
Translated title of the contributionDevelopment of a newly designed oxygen-blowing lance head for LD converters using ceramic materials
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Danzer, Robert, Assessor A (internal)
  • Schenk, Johannes, Assessor B (internal)
Publication statusPublished - 2012

Bibliographical note

embargoed until null

Keywords

  • LD converters
  • steelmaking process
  • oxygen-blowing lance head
  • ceramic materials

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