In-Situ Observation of Fe0.94O Reduction at High Temperature with the Use of Optical Microscopy

Abstract

TORU YAMASHITA, TOMOYA NAKADA, and KAZUHIRO NAGATA Highly (l00) oriented Fe 0.94 O, when physically contacted with graphite, is reduced in various CO partial pressures at isothermal temperatures between 1173 and 1473 K. The reducing behaviors were studied in situ using optical microscopy. The results indicated that the reduction of FeO+CO fi Fe+CO 2 took place anywhere on the surface of the Fe 0.94 O at temperatures above 1173 K. The reaction did not start nor spread from the point where the Fe 0.94 O-graphite were in physical contact. The moving rate of the Fe/Fe 0.94 O interface is classified into three regions (as a function of P CO and also temperature): the slow moving region at low temperatures; the stepwise moving region at medium temperatures and low P CO ; and the constant and fast moving region at high P CO or high temperatures.

Iron production from Fe3O4 and graphite by applying 915MHz microwaves

“…The imminent shortage of high-quality iron ore and fossil fuels such as coal and oil has recently been compelling researchers to develop new steel-making methods based on energy transfer processes that do not involve thermal energy generated by hightemperature gases [1][2][3]. Microwave processing has attracted interest for steel making due its ability to realize volumetric heating and its high energy efficiency [4,5].…”

Influence of Reduction Condition on the Morphology of Newly Formed Metallic Iron During the Fluidized Bed Reduction of Fine Iron Ores and its Corresponding Agglomeration Behavior

“…To deeply clarify the precipitation mechanism of fibrous iron and dense iron in the present study, the as‐reduced samples in pure CO and pure H 2 at 1073 K were collected, respectively to study the reaction interface. The metallic iron only appears during the last reduction step of the iron oxides, namely the reaction Fe 1– x O + H 2 /CO → Fe + H 2 O/CO 2 , and according to the former researches, the reaction could also be expressed as follows: where the Fe vacancies () are originated from non‐stoichiometry and thermal equilibration. After the first iron nucleus is formed, the reduction would proceed with the migration of and 2e – along the Fe/Fe 1– x O interface.…”

Relation between Sticking and Metallic Iron Precipitation on the Surface of Fe2O3 Particles Reduced by CO in the Fluidized Bed

“…The reason was that the effect of temperature on the reduction rate was less strong above 700°C. 17) And the rate of reduction from Fe2O3 to Fe1-xO was fast at high temperature, 18) weakening the effect of concentration of CO on the reduction degree. Therefore, the reduction degree increased slightly with increase of temperature and concentration of CO when sticking happened.…”

“…And the reduction from Fe 2 O 3 to Fe 1-x O was faster than that from Fe 1-x O to Fe, therefore the latter was the controlling step of reduction of the iron oxide. 18) The reduction from Fe 1-x O to Fe in the fluidized bed reactor must proceed through the following steps: 17) (1) Transport of the gaseous reactants (CO) from the bubble phase of the fluidized bed into the emulsion phase.…”