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Energy and environmental optimization of some aspects of EAF practice with novel process solutions

Technical Report:

Abstract

The objective of the present thesis is to optimize the electric arc furnace (EAF) practice from an environmental view point. Two aspects that meet the requirements of the secondary steelmaking industries today, viz. Mo alloying with maximum retainment of the alloying element in molten steel and optimization of foaming by carbonate addition with a view to optimize the energy need of the process. Both these aspects would also have a significant impact on the process economy. Iron molybdate (Fe{sub 2}MoO{sub 4}) has been synthesized from commercial grade materials and proposed as a new potential precursor for steel alloying with Mo. The thermal stabilities of different molybdates, viz. Fe{sub 2}MoO{sub 4}4, CaMoO{sub 4} and MgMoO{sub 4}, were studied using thermogravimetry analysis (TGA). It was found that Fe{sub 2}MoO{sub 4} is the most stable one and doesn't evaporate in Ar atmosphere when heating up to 1573 K. The synthesis of Fe{sub 2}MoO{sub 4} requires high temperature (1373 K) and long holding time (up to 16 hours). In a view of this, the possibilities for in-situ formation of Fe{sub 2}MoO{sub 4} and CaMoO{sub 4} from their precursor mixtures were studied with the aid of high-temperature X-ray diffraction (XRD) and TGA analysis. Laboratory and  More>>
Authors:
Publication Date:
Sep 15, 2010
Product Type:
Technical Report
Report Number:
KTH-MSE-10-41
Resource Relation:
Other Information: Thesis or Dissertation; TH: Doctoral thesis (TeknD); 39 refs., 26 figs., 13 tabs.
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; ENERGY CONSERVATION; STEELS; ARC FURNACES; IRON; MOLYBDATES; SLAGS; FOAMS; DOLOMITE; LIMESTONE
OSTI ID:
1005371
Research Organizations:
Royal Inst. of Technology, Stockholm (Sweden). School of Industrial Engineering and Management, Dept. of Materials Science and Engineering
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: ISBN 978-91-7415-721-5; TRN: SE1107033
Availability:
Available from URI: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24486
Submitting Site:
SWD
Size:
63 p. pages
Announcement Date:
Feb 28, 2011

Technical Report:

Citation Formats

Chychko, Andrei. Energy and environmental optimization of some aspects of EAF practice with novel process solutions. Sweden: N. p., 2010. Web.
Chychko, Andrei. Energy and environmental optimization of some aspects of EAF practice with novel process solutions. Sweden.
Chychko, Andrei. 2010. "Energy and environmental optimization of some aspects of EAF practice with novel process solutions." Sweden.
@misc{etde_1005371,
title = {Energy and environmental optimization of some aspects of EAF practice with novel process solutions}
author = {Chychko, Andrei}
abstractNote = {The objective of the present thesis is to optimize the electric arc furnace (EAF) practice from an environmental view point. Two aspects that meet the requirements of the secondary steelmaking industries today, viz. Mo alloying with maximum retainment of the alloying element in molten steel and optimization of foaming by carbonate addition with a view to optimize the energy need of the process. Both these aspects would also have a significant impact on the process economy. Iron molybdate (Fe{sub 2}MoO{sub 4}) has been synthesized from commercial grade materials and proposed as a new potential precursor for steel alloying with Mo. The thermal stabilities of different molybdates, viz. Fe{sub 2}MoO{sub 4}4, CaMoO{sub 4} and MgMoO{sub 4}, were studied using thermogravimetry analysis (TGA). It was found that Fe{sub 2}MoO{sub 4} is the most stable one and doesn't evaporate in Ar atmosphere when heating up to 1573 K. The synthesis of Fe{sub 2}MoO{sub 4} requires high temperature (1373 K) and long holding time (up to 16 hours). In a view of this, the possibilities for in-situ formation of Fe{sub 2}MoO{sub 4} and CaMoO{sub 4} from their precursor mixtures were studied with the aid of high-temperature X-ray diffraction (XRD) and TGA analysis. Laboratory and industrial trials on steel alloying with Mo were conducted using precursor mixtures as sources of Mo. It was found that the mixture, which contains FeOx, MoO{sub 3} and C (Fe{sub 2}MoO{sub 4} precursor), can provide the Mo yield up to 98 % at both the laboratory as well as industrial trials. The Mo yields even in the case of C+MoO{sub 3} and C+MoO{sub 3}+CaO mixtures were around 93% in these trials. The higher yield for the MoO{sub 3}+C+FeOx mixture was attributed to the stabilization of Mo in the precursor (marked by the decrease in the Gibbs energy of Mo) and the readiness to dissolve in the steel bath. The heat effect of the slag foaming with carbonates addition was studied at 1623 and 1673 K with the aid of thermal analysis technique with a new crucible design. Experiments were conducted by adding limestone and dolomite pieces of defined shapes (together with iron sinkers) in molten slag and monitoring the temperature changes accompanying the decomposition of carbonates. It was found that the decomposition energies for dolomite and limestone for the studied slag composition are in the range 56-79 % of theoretical values, which is linked to the energy saving effect of slag foaming. No influence of sample shape on decomposition energy was found both for limestone and dolomite. The kinetics of slag foaming by limestone particles was studied at 1773 K with the aid of X-ray imaging system. A model was proposed to describe the decrease in foam height with time on the basis of CaO shell formation during decomposition reaction. The energy impact of limestone and raw dolomite addition was examined in a 100-ton EAF. It was found that, in the case of addition of carbonates after the scrap is completely molten; the endothermic heat effects for limestone and dolomite (2255 and 2264 kJ/kg respectively) were only 70 % from theoretical values. This is indicative of the resistance to heat transfer due to increased foaming}
place = {Sweden}
year = {2010}
month = {Sep}
}