Characteristics of Metal Reduction During Prereduction of Chromite types of Ore
Iron and chromium were reduced from chromium spinel at 1300∘С and 1400∘С during 1 and 4 hours. The reduction was carried out with carbon or CO gas in one experiment simultaneously for six samples of three different types of ore. It was established that under these conditions, the CO gas neither reduces chromium nor iron from complex chromium spinel, whereas solid carbon reduces iron and chromium completely. In the mixture of solid reagents at the initial stage of reduction with solid carbon, the carbide shell was formed on the surface of carbon and oxide, accurately reproducing the surface topography of the particles. The formation of the shell indicated a countertransfer of the oxide substance to the surface of carbon and carbon substance to the surface of the oxide through the gas phase. The shell retarded and stopped the reduction process, however, when the shell substance was melted and drained, thereduction process continued. The same shell, but from the Fe–Cr non-carbon alloy, was formed on the surface of the single spinel crystals interspersed in a large volume of magnesium–silicate matrix. The results of the experiments were explained from the standpoint of the theory of the electron reduction mechanism developed by the authors with the formation of plasma in the gas gaps and its participation in the contactless electron-ion exchange between solid reagents.
Keywords: metallization, ferrochrome, theory of reduction, low-temperature plasma, electron-ion exchange
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