Reduction of Ilmenite in the Presence of Sulfur

1990 ◽  
Vol 43 (1) ◽  
pp. 1 ◽  
Author(s):  
C Li ◽  
RR Merritt
Keyword(s):  
Phase Equilibria ◽  
Oxygen Fugacity ◽  
Methanol Solution ◽  
High Grade ◽  
Reduction Temperature ◽  
Synthetic Rutile ◽  
Reduction Time ◽  
Time Required ◽  
Ilmenite Reduction ◽  
Western Australian

Synthetic rutile has been produced from a Western Australian ilmenite by reducing it under controlled oxygen and sulfur fugacities , then leaching out the resulting metallic and sulfide phases with a bromine-in-methanol solution. The grade of the synthetic rutile has been determined as a function of reduction temperature, reduction time and oxygen fugacity. Experimental limitations precluded investigation of different sulfur fugacities. Reductions performed at 1301, 1348 and 1423 K have shown that synthetic rutile produced at 1301and 1348 K has a higher grade than that produced at 1423 K. In addition, the reduction time required to achieve a high-grade product at 1301 and 1348 K has been found to be less than that required at 1423 K. Included in the paper are an indication of how phase equilibria for the Fe- Mn -Ti-O-S system can be used to predict the grades of synthetic rutile produced at other temperatures or sulfur fugacities, and a discussion of how the reported results can be applied to ilmenite reduction in coal-fired kilns.

scholarly journals Effect of Coated Cow Dung on Fluidization Reduction of Fine Iron Ore particles

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1175
Author(s):  
Qiyan Xu ◽  
Zhanghan Gu ◽  
Ziwei Wan ◽  
Mingzhu Huangfu ◽  
Qingmin Meng ◽  
...  
Keyword(s):  
Iron Ore ◽  
Linear Velocity ◽  
Operating Conditions ◽  
Inhibition Mechanism ◽  
Cow Dung ◽  
Reduction Temperature ◽  
Reduction Time ◽  
Reducing Gas ◽  
Fine Iron ◽  
Ironmaking Process

The effects of reduction temperature, gas linear velocity, reduction pressure, reduction time, and reducing gas on the fluidized ironmaking process were studied for the fine iron Newman ore particles (0.154–0.178 mm) and the optimal experimental operating conditions were obtained. Under the optimal conditions, the effects of the coated cow dung on the reduction of fine iron ore particles were studied, and the inhibition mechanism of cow dung on particle adhesion in the fluidized ironmaking process was elucidated. The experimental results show that the optimal operating parameters are linear velocity of 0.6 m/s, reduction pressure of 0.2 MPa, reduction temperature of 1023 K, H2 as the reducing gas, and reduction time of 60 min. Cow dung can react with oxide in the ore powder to form a high melting point substance that can form a certain isolation layer, inhibit the growth of iron whiskers, and improve the fluidization.

scholarly journals Recovery of Iron, Chromium, and Nickel from Pickling Sludge Using Smelting Reduction

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 936 ◽  
Author(s):  
Zhaohui Tang ◽  
Xueyong Ding ◽  
Xinlin Yan ◽  
Yue Dong ◽  
Chenghong Liu
Keyword(s):  
Reduction Process ◽  
Slag Basicity ◽  
Experimental Results ◽  
Iron Ores ◽  
Reduction Temperature ◽  
Smelting Reduction ◽  
Reduction Time ◽  
Temperature Reduction ◽  
Pickling Sludge ◽  
Iron Chromium

This paper reports the recoveries of iron, chromium, and nickel from pickling sludge using coal-based smelting reduction. The influences of slag basicity (CaO/SiO2, which is controlled by high phosphorus oolitic hematite iron ores), reduction temperature, reduction time, and the C/O mole ratio on the recoveries of Fe, Cr, and Ni are investigated systematically. The experimental results show that high recoveries of Fe (98.91%), Cr (98.46%), and Ni (99.44%) are produced from pickling sludge with optimized parameters for the smelting reduction process. The optimized parameters are a slag basicity of 1.5; a reduction temperature of 1550 °C, a reduction time of 90 min, and a C/O mole ratio of 2.0. These parameters can be used as technical support for the recycling of pickling sludge with pyrometallurgy.

scholarly journals Effect of Different Additives on Reaction Characteristics of Fluorapatite During Coal-Based Reduction of Iron Ore

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 923 ◽  
Author(s):  
Yongsheng Sun ◽  
Wentao Zhou ◽  
Yuexin Han ◽  
Yanjun Li
Keyword(s):  
Iron Ore ◽  
Contact Point ◽  
Energy Dispersive Spectrometer ◽  
Structural Evolution ◽  
Reduction Process ◽  
Reduction Degree ◽  
Reduction Temperature ◽  
Exponential Factor ◽  
Reduction Time ◽  
Effect Mechanism

In the coal-based reduction of high phosphorus oolitic hematite, it is particularly important to study the mechanism of phosphorus regulation during the formation of iron metals for the efficient development and utilization of iron ore. In this study, the thermodynamics of the coal-based reduction process of fluorapatite in different mineral systems, effect mechanism of the reduction degree, kinetics, mineral composition, and morphology of structural evolution samples were systematically investigated using FactSage software, single factor analysis, the isothermal method, X-ray diffraction (XRD), scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS). Thermodynamic analysis indicates that the effect of the SiO2–Fe2O3–C system on reducing the initial reduction temperature of fluorapatite was stronger than that of the Al2O3–Fe2O3–C system. The effect mechanism of the reduction degree demonstrates that increasing the dosage of silica, iron oxide, carbon, reduction time, and reduction temperature could promote the reduction reaction of fluorapatite under certain conditions. Dynamics analysis shows that the best kinetic mechanism functions of the SiO2–Fe2O3–C system and the Al2O3–Fe2O3–C system were A1/3 = 1/3(1 − α)[−ln(1 − α)]−2 and A1/2 = 1/2(1 − α)[−ln(1 − α)]−1, respectively. The activation energy and pre-exponential factor of the reduction kinetics equation in the system containing silica were significantly lower than that in the system containing alumina, which explained that the catalytic effect of silica on the reduction of calcium fluorophosphate was far greater than that of alumina. XRD and SEM/EDS analysis indicate that the solid–solid reaction of alumina, silica, iron, and fluorapatite occurred during the reduction process, while calcium aluminate, calcium silicate, and calcium oxide were formed at the contact point. Among them, iron could absorb P2 gas so that it played a greater role in promoting the reduction of fluorapatite. Increasing the reduction temperature and prolonging the reduction time were beneficial to the reduction of fluorapatite.

Prolonged Neoproterozoic high‐grade metamorphism of the Wanni Complex, Sri Lanka: New insights from petrology, phase equilibria modelling, and zircon U–Pb geochronology of partially melted cordierite gneiss from Walpita

2020 ◽  
Vol 55 (9) ◽  
pp. 6147-6168 ◽  
Author(s):  
Eri Hirayama ◽  
Toshiaki Tsunogae ◽  
Sanjeewa P. K. Malaviarachchi ◽  
Yusuke Takamura ◽  
Prasanna L. Dharmapriya ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Phase Equilibria ◽  
High Grade ◽  
Grade Metamorphism ◽  
High Grade Metamorphism

The effects of solid-solid phase equilibria on the oxygen fugacity of the upper mantle

2020 ◽  
Vol 105 (10) ◽  
pp. 1445-1471
Author(s):  
Edward M. Stolper ◽  
Oliver Shorttle ◽  
Paula M. Antoshechkina ◽  
Paul D. Asimow
Keyword(s):  
Phase Equilibria ◽  
Oxygen Fugacity ◽  
Upper Mantle ◽  
Phase Changes ◽  
Primitive Mantle ◽  
Spinel Lherzolite ◽  
Garnet Lherzolite ◽  
Constant Composition ◽  
Al Content ◽  
Mantle Sources

Abstract Decades of study have documented several orders of magnitude variation in the oxygen fugacity (fO2) of terrestrial magmas and of mantle peridotites. This variability has commonly been attributed either to differences in the redox state of multivalent elements (e.g., Fe3+/Fe2+) in mantle sources or to processes acting on melts after segregation from their sources (e.g., crystallization or degassing). We show here that the phase equilibria of plagioclase, spinel, and garnet lherzolites of constant bulk composition (including whole-rock Fe3+/Fe2+) can also lead to systematic variations in fO2 in the shallowest ~100 km of the mantle. Two different thermodynamic models were used to calculate fO2 vs. pressure and temperature for a representative, slightly depleted peridotite of constant composition (including total oxygen). Under subsolidus conditions, increasing pressure in the plagioclase-lherzolite facies from 1 bar up to the disappearance of plagioclase at the lower pressure limit of the spinel-lherzolite facies leads to an fO2 decrease (normalized to a metastable plagioclase-free peridotite of the same composition at the same pressure and temperature) of ~1.25 orders of magnitude. The spinel-lherzolite facies defines a minimum in fO2 and increasing pressure in this facies has little influence on fO2 (normalized to a metastable spinel-free peridotite of the same composition at the same pressure and temperature) up to the appearance of garnet in the stable assemblage. Increasing pressure across the garnet-lherzolite facies leads to increases in fO2 (normalized to a metastable garnet-free peridotite of the same composition at the same pressure and temperature) of ~1 order of magnitude from the low values of the spinel-lherzolite facies. These changes in normalized fO2 reflect primarily the indirect effects of reactions involving aluminous phases in the peridotite that either produce or consume pyroxene with increasing pressure: Reactions that produce pyroxene with increasing pressure (e.g., forsterite + anorthite ⇄ Mg-Tschermak + diopside in plagioclase lherzolite) lead to dilution of Fe3+-bearing components in pyroxene and therefore to decreases in normalized fO2, whereas pyroxene-consuming reactions (e.g., in the garnet stability field) lead initially to enrichment of Fe3+-bearing components in pyroxene and to increases in normalized fO2 (although this is counteracted to some degree by progressive partitioning of Fe3+ from the pyroxene into the garnet with increasing pressure). Thus, the variations in normalized fO2 inferred from thermodynamic modeling of upper mantle peridotite of constant composition are primarily passive consequences of the same phase changes that produce the transitions from plagioclase → spinel → garnet lherzolite and the variations in Al content in pyroxenes within each of these facies. Because these variations are largely driven by phase changes among Al-rich phases, they are predicted to diminish with the decrease in bulk Al content that results from melt extraction from peridotite, and this is consistent with our calculations. Observed variations in FMQ-normalized fO2 of primitive mantle-derived basalts and peridotites within and across different tectonic environments probably mostly reflect variations in the chemical compositions (e.g., Fe3+/Fe2+ or bulk O2 content) of their sources (e.g., produced by subduction of oxidizing fluids, sediments, and altered oceanic crust or of reducing organic material; by equilibration with graphite- or diamond-saturated fluids; or by the effects of partial melting). However, we conclude that in nature the predicted effects of pressure- and temperature-dependent phase equilibria on the fO2 of peridotites of constant composition are likely to be superimposed on variations in fO2 that reflect differences in the whole-rock Fe3+/Fe2+ ratios of peridotites and therefore that the effects of phase equilibria should also be considered in efforts to understand observed variations in the oxygen fugacities of magmas and their mantle sources.

scholarly journals Kinetic Studies on Gas-Based Reduction of Vanadium Titano-Magnetite Pellet

2018 ◽  
Author(s):  
Junwei Chen ◽  
Liang Mi ◽  
Yang Jiao ◽  
Xidong Wang
Keyword(s):  
Early Stage ◽  
Reduction Process ◽  
Kinetic Studies ◽  
Product Layer ◽  
Diffusion Control ◽  
Reduction Degree ◽  
Reduction Temperature ◽  
Pellet Size ◽  
Reduction Time ◽  
Time Reduction

Vanadium titano-magnetite is a significant resource in China, and in this study, we characterize its isothermal reduction mechanisms in the mixture of H2, CO, and N2 where the variables considered here include reduction time, reduction temperature, gas composition, and pellet size. The kinetics of the reduction process are mainly studied, which follows a shrinking core model. The results indicate that the reduction degree of oxidized VTM pellets increases with the increase of reduction time, reduction temperature but decreases with the increase of pellet size. Moreover, we found that an increase of H2/(H2+CO) ratio induces an increase of the reduction degree. Then the transformation of main Ti-bearing mineral phases is discussed, and the most probable reaction mechanism is revealed. In the whole reduction process, the kinetic results confirm the existence of an early stage and a latter stage, which are controlled by interface chemical reaction and diffusion, respectively. Furthermore, the results show that the diffusion-control step can be observably shortened with the decrease of pellet size because a thinner product layer is formed during the reduction process. Our study thus provides a valuable technical basis on the VTM industrial application.

scholarly journals The Effects of High-Grade Metamorphism on Cr-Spinel from the Archean Sittampundi Complex, South India

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1370
Author(s):  
Davide Lenaz ◽  
Bidyananda Maibam ◽  
Jacob Adetunji ◽  
Henrik Skogby
Keyword(s):  
Oxygen Fugacity ◽  
Electron Microprobe ◽  
South India ◽  
Structural Data ◽  
Structural Behavior ◽  
High Grade ◽  
Grade Metamorphism ◽  
High Grade Metamorphism ◽  
Mössbauer Data ◽  
Very High

We investigated the crystal and structural behavior of Cr-bearing spinels from the Archean chromitites of Sittampundi (India), which had been subjected to very high-grade metamorphism. The structural data show that their oxygen positional parameters are among the highest ever recorded for Cr-bearing spinels with similar Cr# and Mg# and very similar to those found for other Archean occurrences. The general agreement between electron microprobe and Mössbauer data indicates that the analyzed spinels are stoichiometric. It is therefore most likely that the PH2O and Ptotal values as well as both the oxygen fugacity and the temperature reached during high-grade metamorphism inhibited the possibility of the non-stoichiometry of chromites, contrary to what can happen in ophiolites, where non-stoichiometry has recently been documented.

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