1994 Volume 80 Issue 7 Pages 501-506
The activity of iron chromite in solid FeO·Cr2O3-MgO·Cr2O3 spinel, saturated with Cr2O3, was determined at 1573 K, by the equilibrium measurement of iron dissolved in liquid silver held in the spinel crucible with CO-CO2 gas mixture, to clarify the thermodynamic properties of chromium ores used in ferrochromium industry.
The solubility of Cr2O3 in FeO·Cr2O3-MgO·Cr2O3 spinel phase was found to be negligibly small. The free energy of formation of FeO·Cr2O3 was determined as follows;
Fe (s) + 1 / 2O2(g) +Cr2O3 (s) = FeO·Cr2O3 (s),
ΔG0 =-307600 + 66.82 T (J/ mol).
(1423-1723 K)
The activities of constituents in FeO·Cr2O3-MgO·Cr2O3 spinel solid solution coexisted with Cr2O3 showed negative deviation from ideality. It was observed that the spinel solid solution took regular solution behavior, and α-function of FeO·Cr2O3-MgO·Cr2O3 system was determined as follows;
αFeO·Cr2O3 = RTlnγFeO·Cr2O3 / (1-NFeO·Cr2O3) 2 =α MgO·Cr2O3 = RTlnγMgO·Cr2O3/(1-NMgO·Cr2O3 ) 2=-12800 (J).
