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Reduction kinetics of regenerated iron oxide from scale with hydrogen: Reduction kinetics related to the Flash Ironmaking technology
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
2018 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The possibility and the rate of reduction of regenerated iron oxide from scale related to the Flash ironmaking (FIM) technology have been studied. There are promising environmental benefits for reducing the iron oxide with FIM technology as an alternative to the BF process. There is little information about the reduction of fine powder with FIM as the technology is under development. The prospect of reducing recovered iron oxide from scale by hydrogen in FIM is attractive, for the reason that scale is a sizeable by-product of 33 million tons per year produced worldwide. The Reduction kinetics of regenerated iron oxide from scale with a particle size of 0.56 µm with hydrogen was evaluated. The material was reduced in an LFR within the temperature interval of 600-900 °C, partial pressure of H2 within 0.1-0.6 atm and residence time within 1.5-7.5 seconds. The chemical composition of the samples were analyzed with ICP-OES. Over 90 % reduction degree was achieved with a metallization degree of 94 %. It was evident that temperature, partial pressure of H2 and the residence time affected the reduction rate. The rate of reduction could be described with a nucleation and growth rate equation with an Avrami parameter of 0.5, the partial pressure dependence of 1.4 and the activation energy of 137 kJ/mol. The reduction degree met sufficient amount to determine that the FIM technology can be a reduction process for scale in the future.

Abstract [sv]

Möjligheten och reduktionsgraden av regenererad järnoxid från glödskal kopplat till FIM-tekniken (Flash ironmaking) har studerats. Det finns lovande miljöfördelar med att minska järnoxiden med FIM-teknik som ett alternativ till BF-processen. Det finns lite information om reduktion av fint pulver med FIM eftersom tekniken är under utveckling. Att reducera järnoxid från glödskal med väte i FIM är attraktiva, därför att glödskal är en stor biprodukt på 33 miljoner ton per år som produceras över hela världen. Reduktionskinetiken för regenererad järnoxid från glödskal med en partikelstorlek av 0,56 um reducerad med väte utvärderades. Materialet reducerades i en LFR inom temperaturintervallet 600-900 ° C, partialtryck av H2 inom 0,1-0,6 atm och uppehållstid inom 1,5-7,5 s. Den kemiska sammansättningen av proverna analyserades med ICP-OES. Över 90% reduktionsgrad uppnåddes med en metalliseringsgrad av 94%. Det var uppenbart att temperaturen, partialtrycket av H2 och uppehållstiden påverkade reduktionshastigheten. Reduktionshastigheten kan beskrivas med en kärnbildnings- och tillväxthastighetsekvation med en Avrami-parameter på 0,5, partialtryckberoende av 1,4 och aktiveringsenergin 137 kJ / mol. Reduktionsgraden uppnådde tillräcklig nivå för att fastställa att FIM-tekniken kan bli en reduktionsprocess för glödskal i framtiden.

Place, publisher, year, edition, pages
2018. , p. 41
Keywords [en]
Iron oxide, Hydrogen, Reduction, Flash Ironmaking, Scale, Fine particle
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-235482OAI: oai:DiVA.org:kth-235482DiVA, id: diva2:1251163
External cooperation
University of Utah
Subject / course
Applied Process Metallurgy
Educational program
Master of Science in Engineering - Materials Design and Engineering
Supervisors
Examiners
Available from: 2018-10-03 Created: 2018-09-26 Last updated: 2018-10-03Bibliographically approved

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