Gaseous Reduction of Titania-ferrous Solution Ore by H₂–Ar Mixture

Abstract

The reductions of titania-ferrous solution ore (TFSO) ranging from 800°C to 1100°C temperature and 10 to 100 vol% H₂–Ar gas mixture were conducted to account for the optimization of reduction parameters, the phase transition behaviors and solid solubility changes with Fe and Ti elements segregation and enrichment, and the micro morphology features in reduction process. 40 vol% of hydrogen in reducing gas, as well as 900°C reaction temperature was the suitable parameters when simultaneously considering the growth of reduction rate and the reasonable economy cost. The reduction of Fe₃O₄ contained in titanomagnetite (TTM) was proceeding earlier than that of ulvöspinel (Fe₂TiO₄), even though Fe₂TiO₄ was also the ingredient of TTM. The initial ilmenite was reduced quickly at primary stage, after that, there were also newly born ilmenite which experienced accumulation and vanishment, along with transformation of Fe₂TiO₄ and ferropseudobrookite (FeTi₂O₅). Although TiO₂ was appeared as early as 5 min, the low valence titanium (Ti₃O₅ and Ti₂O₃) were just observed at the end of reduction, and it was mainly because of the existence of iron oxide, resulting in the weak reduction potential to the titanium oxide. For the non-homogeneous TFSO particles, the lamellas showed a harder reducibility than the substrates and a different priority reduction positions in terms of the central and the edge. For the homogeneous TFSO particles, the reduction was carried out in an outside-in way, which was preferential along some interphase strips that had a lower gangue elements distribution.

The microscopic composition change of one kind of TFSO particle (non-homogeneous particle with lamella TTH phase exsolved from substrate) during reduction process in 100 vol% H₂ atmosphere at 900°C for different time. These kinds of lamellas were firstly reduced from the center position forming the pore and dot reduced Fe.