Thermodynamic analysis of chromium reduction from oxide Cr2O3
https://doi.org/10.17073/0368-0797-2020-11-12-935-945
Abstract
Thermodynamic analysis of chromium reduction from its oxide in gas phase Н2 – Н2О – СО – СО2 in contact with carbon was performed. Oxidation potential (pO2 ) was determined by two nomograms in the coordinates
and
taking into account condition normalizations xH2O + xH2 + xCO2+ xCO = 1. In calculations, possible parameters of reduction of chromium from Cr2O3 oxide were determined by ratio of dissociation elasticity of the oxide and oxidation potential of the gas phase. In the СО – СО2 – С system, chromium is reduced at temperature of 1505 K if xCO > 0.9995. At this temperature, Cr2O3 compound is reduced in water gas of the following composition xH2 = 0.0186, xH2O = 0.28·10–4, xCO = 0.9809, xCO2 = 4.86·10–4, for which the oxidation potential is equal to dissociation elasticity of oxide
With an increase in hydrogen concentration from 0.0186 to 0.99, oxidation potential of water gas in contact with carbon decreases by four orders of magnitude to
This should lead to a significant increase in reduction rate. In such a gaseous atmosphere, it is possible to reduce chromium at temperature of 1230 K. It is technologically simple to obtain reducing water gas and at the lowest cost, for example, by heating water vapor in contact with carbon. It is shown that at temperature of 1500 K water gas is obtained with traces of Н2О and СО2 compounds with parameters xH2 = 0.4999, xCO = 0.4996,
Oxidizing potential of such a gas is less than that of chromium oxide, and this difference significantly increases with increasing temperature.
About the Authors
Yu. S. Kuznetsov
South Ural State University
Russian Federation
Russian Federation
Cand. Sci. (Eng.), Professor of the Chair of Materials Science and Physical Chemistry of Materials
Chelyabinsk
O. I. Kachurina
South Ural State University
Russian Federation
Russian Federation
Cand. Sci. (Chem.), Assist. Professor of the Chair of Theoretical and Applied Chemistry
Chelyabinsk
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Review
For citations:
Kuznetsov Yu.S., Kachurina O.I. Thermodynamic analysis of chromium reduction from oxide Cr2O3. Izvestiya. Ferrous Metallurgy. 2020;63(11-12):935-945. (In Russ.) https://doi.org/10.17073/0368-0797-2020-11-12-935-945
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