Melting Rate of Iron Oxide Pellets into Iron Melt

概要

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The melting rate of iron oxide pellets into iron melt and the reduction rate of pellets by carbon in iron melt were obtained by measuring the evolution rate of CO gas. The pellets were made from iron oxide powder by pressing and sintering and were not crushed into pieces when added onto the iron melt. The effects of the iron oxide phase, the oxide additives in pellets, and the temperature and the carbon content of iron melts on the melting and the reduction rates were investigated. The following results were obtained:(1)It has been found that the heat transfer was not the rate-determining step for the two rates. It is considered that the carbon diffusion in a boundary layer on the iron melt surface could be the rate-determining step.(2) The total reduction rate was constant for reduction degrees from about 20% to about 70%, where solid iron oxides were reduced by carbon dissolved in iron melt.(3) The apparent activation energy of the melting of pellets into the carbon saturated iron melt was 35 for Fe2O3; 18 and 41 for Fe3O4 above and below 1470°C, respectively; 44 and 79kcal/mol for FeO above and below 1470°C, respectively.(4) The melting rate of Fe2O3, Fe3O4 and FeO pellets into the iron melt at 1570°C was proportional to C0.57, C0.45 and C0.42 respectively, where C denotes the weight percentage of carbon in an iron melt. The minimum amount of CO gas evolved was obtained at about 2%C.
The Iron and Steel Institute of Japanの論文