Reduction of Panzhihua titanium-bearing oxidized pellets by CO-N₂-H₂ gas

Abstract

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.

Keywords

titanomagnetite pellet / carbon monoxide / hydrogen / reduction / blast furnace

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