Entwicklung von Methoden zur Bewertung und Kontrolle der Alkalienbilanz eines Hochofens

Translated title of the contribution: Development of methods to evaluate und control the alkali balance of a blast furnace

Alexander Spatzker

Research output: ThesisDoctoral Thesis

Abstract

Potassium and sodium compounds are known as harmful elements for the blast furnace process. They promote the formation of scaffolds, change the softening behavior of the burden and reduce the strength of the coke. They are also known for the formation of cyanides and chlorides, which can get into the gas cleaning system and cause problems there. Due to their chemical and physical properties, alkaline compounds form circuits and can accumulate locally in the blast furnace. To assure a stable reduction and melting process it is necessary to understand the behavior of alkali compounds in different zones of the blast furnace. In this work the concentration and the kinds of alkali compounds above the blast furnace radius in a depth of 4.5 m under the burdens surface is measured by in-burden dust extraction via horizontal mess lance are investigated. The dust samples obtained were chemically analyzed for their composition and then examined for their bond forms by means of X-ray spectroscopy. The results are compared and discussed with stability diagrams created with FACTSAGE®, taking into account local temperatures and gas atmospheres. The occurrence of various primary compounds and compounds that are formed by secondary reactions is determined and discussed. It can be shown that cyanide compounds play a major role in the high-temperature zone of a blast furnace with center flow operation. Furthermore, the concentration of alkalis in the top dust and in the wash water of the gas cleaning system is examined and compared with the results from the in-burden measurements using a horizontal measuring probe. In addition, possible influences of furnace parameters such as hot metal temperature, silicon content in hot metal and the optical basicity of the slag on the alkali and especially cyanide content in the dust are shown and discussed. It can be shown that, under normal process conditions, the majority of the alkali metal cyanides are decomposed at the top of the blast furnace. Different possible degradation reactions are discussed from a thermodynamic point of view.
Translated title of the contributionDevelopment of methods to evaluate und control the alkali balance of a blast furnace
Original languageGerman
QualificationDr.mont.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Schenk, Johannes, Assessor A (internal)
  • Deike, Rüdiger, Assessor B (external), External person
Publication statusPublished - 2020

Bibliographical note

embargoed until null

Keywords

  • Blast Furnace
  • Alkalis
  • Cyanides
  • In-Burden Measurement
  • Top Dust
  • Washing Water
  • X-ray spectroscopy

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