A compilation of slag foaming phenomenon research

Theoretical studies, industrial experiments and modelling

Research output: Book/ReportReportProfessional

Abstract

A literature study was made on the foaming phenomenon in the modern electric arc furnace (EAF) stainless steelmaking process. Slag foaming has become an important feature of the EAF process. The chemical and physical conditions of the slag, which affect the foaming phenomenon of the slag-steel system, appear to be relatively complicated to control in the manufacture of stainless steel. The foaming index is a parameter that quantifies the ability of slag to generate foam from either injected gas or gas that is generated within the slag or metal. In the case of ideal slagging, the foaming index is equal to the average foam life. The foaming index decreases with increasing viscosity and increases with decreasing viscosity. Various techniques based on dimensional analysis of the kinetic properties of the slag have been applied in order to find the relationship describing the foaming index. In industrial experiments, the control methods of the slag foaming operations are based on the visual observation or on noise emitted by the EAF vessel. The lower Cr2O3 content slags and large initial FeO content slags are more foaming. The foaming is also observed to promote chromium recovery. The foaming index for the slags is observed to be relatively similar, due to the similarities between viscosity, density and surface energy values, although their compositions are quite different. The foamy slag provides protection for the melt against nitrogen pick-up. The foaming capability of slags can be enhanced by the addition of appropriate materials such as limestone and calcium nitrate. In the modelling studies, the aim is to understand and predict foaming in EAF steelmaking. The slag foaming caused by slag-graphite reaction is dependent mainly on the CO-gas evolution rate. Decarburisation and slag formation models consider the rate phenomena for decarburisation and the carbon-FeO reaction in the slag, and the mass balance for each phase with the melting behaviour of pig iron scrap and fluxes. A recent thermodynamic model of the EAF process for stainless steel calculates the evolution of temperature and the composition of slag and metal phases with time. In the slag foaming in the EAF model the potential foaming is very high when using high amounts of input materials. The actual foam is limited by the height at which the slag is flushed out or by the volume of slag. At the end of the process the foam decays due to lower CO-gas generation.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages134
ISBN (Electronic)978-951-38-7897-9
Publication statusPublished - 2012
MoE publication typeNot Eligible

Publication series

NameVTT Technology
PublisherVTT
Volume63
ISSN (Print)2242-122X

Fingerprint

Slags
Experiments
Electric arcs
Furnaces
Foams
Viscosity
Gases
Stainless steel
Iron scrap
Steelmaking furnaces
Pig iron
Steelmaking
Limestone
Metals
Chemical analysis
Interfacial energy

Keywords

  • Electric arc furnace
  • EAF
  • stainless steel
  • slag foaming
  • gas generation
  • foam indesx
  • foam life
  • foaming
  • surface energy
  • viscosity
  • interface
  • basicity
  • temperature
  • gas velocity
  • bubble size
  • dimensional analysis
  • carbon
  • CO-gas
  • CaO-SiO2-FeO
  • Cr2O3
  • modelling
  • reconciliation
  • mass balance
  • reaction rate
  • kinetics
  • dynamics
  • Fact
  • Fortran
  • Chemapp

Cite this

Liukkonen, M., Penttilä, K., & Koukkari, P. (2012). A compilation of slag foaming phenomenon research: Theoretical studies, industrial experiments and modelling. Espoo: VTT Technical Research Centre of Finland. VTT Technology, Vol.. 63
Liukkonen, Matti ; Penttilä, Karri ; Koukkari, Pertti. / A compilation of slag foaming phenomenon research : Theoretical studies, industrial experiments and modelling. Espoo : VTT Technical Research Centre of Finland, 2012. 134 p. (VTT Technology, Vol. 63).
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abstract = "A literature study was made on the foaming phenomenon in the modern electric arc furnace (EAF) stainless steelmaking process. Slag foaming has become an important feature of the EAF process. The chemical and physical conditions of the slag, which affect the foaming phenomenon of the slag-steel system, appear to be relatively complicated to control in the manufacture of stainless steel. The foaming index is a parameter that quantifies the ability of slag to generate foam from either injected gas or gas that is generated within the slag or metal. In the case of ideal slagging, the foaming index is equal to the average foam life. The foaming index decreases with increasing viscosity and increases with decreasing viscosity. Various techniques based on dimensional analysis of the kinetic properties of the slag have been applied in order to find the relationship describing the foaming index. In industrial experiments, the control methods of the slag foaming operations are based on the visual observation or on noise emitted by the EAF vessel. The lower Cr2O3 content slags and large initial FeO content slags are more foaming. The foaming is also observed to promote chromium recovery. The foaming index for the slags is observed to be relatively similar, due to the similarities between viscosity, density and surface energy values, although their compositions are quite different. The foamy slag provides protection for the melt against nitrogen pick-up. The foaming capability of slags can be enhanced by the addition of appropriate materials such as limestone and calcium nitrate. In the modelling studies, the aim is to understand and predict foaming in EAF steelmaking. The slag foaming caused by slag-graphite reaction is dependent mainly on the CO-gas evolution rate. Decarburisation and slag formation models consider the rate phenomena for decarburisation and the carbon-FeO reaction in the slag, and the mass balance for each phase with the melting behaviour of pig iron scrap and fluxes. A recent thermodynamic model of the EAF process for stainless steel calculates the evolution of temperature and the composition of slag and metal phases with time. In the slag foaming in the EAF model the potential foaming is very high when using high amounts of input materials. The actual foam is limited by the height at which the slag is flushed out or by the volume of slag. At the end of the process the foam decays due to lower CO-gas generation.",
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year = "2012",
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publisher = "VTT Technical Research Centre of Finland",
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Liukkonen, M, Penttilä, K & Koukkari, P 2012, A compilation of slag foaming phenomenon research: Theoretical studies, industrial experiments and modelling. VTT Technology, vol. 63, VTT Technical Research Centre of Finland, Espoo.

A compilation of slag foaming phenomenon research : Theoretical studies, industrial experiments and modelling. / Liukkonen, Matti; Penttilä, Karri; Koukkari, Pertti.

Espoo : VTT Technical Research Centre of Finland, 2012. 134 p. (VTT Technology, Vol. 63).

Research output: Book/ReportReportProfessional

TY - BOOK

T1 - A compilation of slag foaming phenomenon research

T2 - Theoretical studies, industrial experiments and modelling

AU - Liukkonen, Matti

AU - Penttilä, Karri

AU - Koukkari, Pertti

PY - 2012

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N2 - A literature study was made on the foaming phenomenon in the modern electric arc furnace (EAF) stainless steelmaking process. Slag foaming has become an important feature of the EAF process. The chemical and physical conditions of the slag, which affect the foaming phenomenon of the slag-steel system, appear to be relatively complicated to control in the manufacture of stainless steel. The foaming index is a parameter that quantifies the ability of slag to generate foam from either injected gas or gas that is generated within the slag or metal. In the case of ideal slagging, the foaming index is equal to the average foam life. The foaming index decreases with increasing viscosity and increases with decreasing viscosity. Various techniques based on dimensional analysis of the kinetic properties of the slag have been applied in order to find the relationship describing the foaming index. In industrial experiments, the control methods of the slag foaming operations are based on the visual observation or on noise emitted by the EAF vessel. The lower Cr2O3 content slags and large initial FeO content slags are more foaming. The foaming is also observed to promote chromium recovery. The foaming index for the slags is observed to be relatively similar, due to the similarities between viscosity, density and surface energy values, although their compositions are quite different. The foamy slag provides protection for the melt against nitrogen pick-up. The foaming capability of slags can be enhanced by the addition of appropriate materials such as limestone and calcium nitrate. In the modelling studies, the aim is to understand and predict foaming in EAF steelmaking. The slag foaming caused by slag-graphite reaction is dependent mainly on the CO-gas evolution rate. Decarburisation and slag formation models consider the rate phenomena for decarburisation and the carbon-FeO reaction in the slag, and the mass balance for each phase with the melting behaviour of pig iron scrap and fluxes. A recent thermodynamic model of the EAF process for stainless steel calculates the evolution of temperature and the composition of slag and metal phases with time. In the slag foaming in the EAF model the potential foaming is very high when using high amounts of input materials. The actual foam is limited by the height at which the slag is flushed out or by the volume of slag. At the end of the process the foam decays due to lower CO-gas generation.

AB - A literature study was made on the foaming phenomenon in the modern electric arc furnace (EAF) stainless steelmaking process. Slag foaming has become an important feature of the EAF process. The chemical and physical conditions of the slag, which affect the foaming phenomenon of the slag-steel system, appear to be relatively complicated to control in the manufacture of stainless steel. The foaming index is a parameter that quantifies the ability of slag to generate foam from either injected gas or gas that is generated within the slag or metal. In the case of ideal slagging, the foaming index is equal to the average foam life. The foaming index decreases with increasing viscosity and increases with decreasing viscosity. Various techniques based on dimensional analysis of the kinetic properties of the slag have been applied in order to find the relationship describing the foaming index. In industrial experiments, the control methods of the slag foaming operations are based on the visual observation or on noise emitted by the EAF vessel. The lower Cr2O3 content slags and large initial FeO content slags are more foaming. The foaming is also observed to promote chromium recovery. The foaming index for the slags is observed to be relatively similar, due to the similarities between viscosity, density and surface energy values, although their compositions are quite different. The foamy slag provides protection for the melt against nitrogen pick-up. The foaming capability of slags can be enhanced by the addition of appropriate materials such as limestone and calcium nitrate. In the modelling studies, the aim is to understand and predict foaming in EAF steelmaking. The slag foaming caused by slag-graphite reaction is dependent mainly on the CO-gas evolution rate. Decarburisation and slag formation models consider the rate phenomena for decarburisation and the carbon-FeO reaction in the slag, and the mass balance for each phase with the melting behaviour of pig iron scrap and fluxes. A recent thermodynamic model of the EAF process for stainless steel calculates the evolution of temperature and the composition of slag and metal phases with time. In the slag foaming in the EAF model the potential foaming is very high when using high amounts of input materials. The actual foam is limited by the height at which the slag is flushed out or by the volume of slag. At the end of the process the foam decays due to lower CO-gas generation.

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KW - EAF

KW - stainless steel

KW - slag foaming

KW - gas generation

KW - foam indesx

KW - foam life

KW - foaming

KW - surface energy

KW - viscosity

KW - interface

KW - basicity

KW - temperature

KW - gas velocity

KW - bubble size

KW - dimensional analysis

KW - carbon

KW - CO-gas

KW - CaO-SiO2-FeO

KW - Cr2O3

KW - modelling

KW - reconciliation

KW - mass balance

KW - reaction rate

KW - kinetics

KW - dynamics

KW - Fact

KW - Fortran

KW - Chemapp

M3 - Report

T3 - VTT Technology

BT - A compilation of slag foaming phenomenon research

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Liukkonen M, Penttilä K, Koukkari P. A compilation of slag foaming phenomenon research: Theoretical studies, industrial experiments and modelling. Espoo: VTT Technical Research Centre of Finland, 2012. 134 p. (VTT Technology, Vol. 63).