Reduction Extraction Kinetics of Titania and Iron from an Ilmenite by H2–Ar Gas Mixtures

Abstract

Reduction of an ilmenite concentrate as a natural concentration containing 49.78 mass% TiO 2 and 27.96 mass% total Fe by H 2 -Ar gas mixtures was investigated from 1 073 to 1 273 K. Both the reduction degree and reduction rate increased with the increase of temperature and hydrogen content. The reduction degree of the ilmenite decreased due to the presence of impurities including manganese and silicon oxides in the ilmenite concentrate. During the reduction, the formation of manganese and silicon oxide-enriched zones prevented complete reduction of Fe 2ϩ . The reduction products were characterized using X-ray diffraction, scanning electronic microscope with energy disperse spectroscopy and optical microscopy analysis, respectively. The main phases in reduced products were reduced iron, rutile, reduced rutiles, pseudobrookite and Ti 3 O 5 . The reduction reaction proceeded topochemically and the reduction kinetics was discussed. It was found that the rate controlling step was the diffusion of hydrogen gas in the reduced layer.

Reduction Kinetics of FeTiO3 Powder by Hydrogen

“…The unreacted core shrinking model can be used to describe the reduction kinetics of FeTiO3 by hydrogen. 1,7) According to unreacted core shrinking model, the reduction of FeTiO3 by hydrogen can be approximately divided into three main steps: diffusion of hydrogen in the gas phase boundary; diffusion of hydrogen in the product layer; chemical reaction at the interface. Generally, the first step is not the rate controlling step.…”

“…[1][2][3][4][5][6] However, the kinetic mechanism is still unclear. Because the main component of ilmenite is FeTiO 3 , it is important to clear the reduction kinetics of FeTiO 3 first, which is the main aim of the present work.…”

Improving the electrical properties of niobium-doped titania sputtering targets by sintering in oxygen-deficient atmospheres

“…Furthermore, Shin et al [20] showed that the electronic conductance of TiO 2 particles can be increased by more than one order of magnitude by changing the annealing atmosphere from pure Ar to 95% Ar-5% H 2 . Wang et al [21] indicated that increasing the hydrogen concentration in Ar-H 2 gas mixture is obviously beneficial to the reduction degree of ilmenite. An Ar-H 2 atmosphere has been regarded as a reducing atmosphere for TiO 2 [17,[20][21][22].…”

Effect of Hydrogen Addition on Reduction Kinetics of Iron Oxides in Gas-injection BF

“…23,30) In the reduction series, the transformations of Fe 2 O 3 →Fe 3 O 4 and Fe 3 O 4 →FeO are much easier than that of FeO→Fe, thus the two former reactions can be ignored in the kinetics analysis. 31,32) In addition, the water gas shift reaction will also take place besides for the reduction of iron oxides, which will restrict the gas utilization in gas-injection BF. The FeO reduction in the gases mixture and the water gas reaction can be expressed as follows: …”