Fundamental Researches on Smelting of Sulphide Ores. V : On the Equilibrium in the Reduction of Solid Cobaltous Sulphide by Hydrogen Gas

The equilibrium in the reduction of solid cobaltous sulphide by hydrogen gas were investigated with the aid of the flow method. The effect of temperature upon the equilibrium constant and the standard free energy change for the reaction over the temperature range 631~775℃ were determined as follows : CoS(s)+H_2=Co(s)+H_2S ; log K_p=-3, 516/T+1.323, ΔF°=16, 082-6.051T. By combining these equations with the known ones of hydrogen sulphide gas, the dissociation pressure and the standard free energy change in the dissociation of solid cobaltous sulphide were represented as a function of temperature by the following equations : 2CoS(s)=2Co(s)+S_2 ; log P_<S_2>=- 16.418/T+7.746, ΔF°=75, 100-35.43T. Using these results and other thermodynamical data, the heat change and the standard free energy change of formation of solid cobaltous sulphide were computed. Co+S(r)=CoS ; ΔH298.1=-22, 770, ΔF°298.1=-22, 960.