Reduction of Panzhihua titanium-bearing oxidized pellets by CO-N_2-H_2 gas

The effect of H2 gas content on the reduction of Panzhihua titanomagnetite concentrate pellets by carbon monoxide was investigated by isothermal reduction experiment using CO-N2-H2 gas mixtures in a vertical electric resistance furnace.The morphology and phase transformation of reduced samples obtained were detected by scanning electron microscopy,energy disperse spectroscopy analysis and X-ray diffractometry respectively.The results show that increasing H2 content will enhance the initial stage of reduction rate apparently.There are two reasons responsible for this effect,one is that H2 accelerates the chemical reaction,and the other is that the addition of H2 gas can improve the porosity of pellet intensively.It is noteworthy that this effect is more obvious when the reduction temperature reaches 1473 K with sticking phenomenon happening.There are no crystalline phases which can be found such as ulvospinle,ilmenite,ferrous-pseudobrookite and any titanium oxide except titanomagnetite（TTM）.The reduction progress is suggested as follows:1) Fe2O3→Fe3O4→FeO→Fe;2) Fe2TiO5→Fe2TiO4+Fe3O4→TTM.Element Al migrates and gets enriched in high titanium content iron ores,and eventually Al to Ti molar ratio is 1:3.Al is likely to dissolve in titanium iron oxides to form a kind of composite iron compound,which results in the restrain of reduction.