Effects of gas composition, gas velocity and particle size on reduction rate, the dissociation of CO during reduction and kinetics of reduction have been studied.
The reduction rate increased remakably with the reducing gas contained over 25% H₂. In case of H₂ 40%, CO 60% mixture, the complete reduction was obtained at 950°C for 2 hours in ilmenite and at 900°C for 2 hours in titaniferous iron sand.
The particle size-should be prepared under 100 mesh in ilmenite and under 80 mesh in titaniferous iron sand.
The influence of gas velocity was studied in the reduction of ilmenite with H₂ 40%, CO 60% mixture. When it exceeded over 1.32cm/sec at 950°C, it had little effect on the reduction rate.
The dissociation of CO during reduction was recognized markedly at 400-700°C in titaniferous iron sand, but in ilmenite it was not at all.
At first the reaction was the 1st order type, approaching the complete reduction diffusion took the rate controlling step.
While activation energies were almost the same in the reduction of ilmenite with H₂ 100%, CO 100% and H₂ 40%, CO 60% mixture, the reaction velocity constant of H₂ 100% was 8 times as large as of CO 100% and twice of H₂ 40%, CO 60% mixture.