Experimental analysis for thermally non-equilibrium state under microwave irradiations a greener process for steel making

Motoyasu Sato, Akihiro Matsubara, Sadatsugu Takayama, Shigeru Sudo, Osamu Motojima, Kazuhiro Nagata, Kotaro Ishizaki, Tetsuro Hayashi, Dinesh Kumar Agrawal, Rustum Roy

Research output: Chapter in Book/Report/Conference proceedingConference contribution

12 Scopus citations

Abstract

Highly pure pig irons were produced in a multimode microwave reactor from powdered iron ores with carbon as a reducing agent in the nitrogen atmosphere. The grains in compacted powder absorb microwave energy selectively. Microwave-matter interaction creates thermal non-equilibrium state microscopically and enhances chemical reactions and the phase mixing at the grain boundaries very rapidly. The visible light spectroscopic techniques was used to monitor the progress of the reactions. Up to 650°C, the heated powders radiate the continuous spectrum of blackbody emission. The small non-equilibrium hot spots rise, move and finally burst in to brighter light emitting from all over the surface at 650°C. CN molecules and Fe (I) atoms were identified in the recorded spectrum. These bursts are similar to the "ignition propagation" normally observed in chemical reactions. The line spectra originated from CO molecules have not been detected yet. The solid-solid reaction could be expected between the iron oxides and carbon to produce CO2 directly. A loss in the sample weight was accelerated during the excess-emission. These are the clear evidence that microwaves cause thermally non-equilibrium state and accelerate reduction process. The reduction of iron ore is completed at 1380°C and relatively very pure pig iron was produced. It should be noted that the impurity level of Mg, S, Si, P and Ti is only 5-10% of what is found in the pig irons produced by modem conventional blast furnaces in the steel industries. The necessary amount of carbon needed was 1/2 compared to conventional blast furnace to produce the unit weight of steel, if we applied renewable energy or nuclear power for the microwave excitations.

Original languageEnglish (US)
Title of host publicationSohn International Symposium
Subtitle of host publicationAdvanced Processing of Metals and Materials - Proceedings of the International Symposium
Pages157-170
Number of pages14
StatePublished - Dec 1 2006
Event2006 TMS Fall Extraction and Processing Division: Sohn International Symposium - San Diego, CA, United States
Duration: Aug 27 2006Aug 31 2006

Publication series

Name2006 TMS Fall Extraction and Processing Division: Sohn International Symposium
Volume5

Other

Other2006 TMS Fall Extraction and Processing Division: Sohn International Symposium
CountryUnited States
CitySan Diego, CA
Period8/27/068/31/06

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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