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1
Content available The mechanism of CaCO3 in the gas-based direct reduction of a high-phosphorus oolitic iron ore
Wu Shichao, Li Zhengyao, Sun Tichang, Kou Jue, Xu Chengyan
Physicochemical Problems of Mineral Processing
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2021
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Vol. 57, iss. 4
117--124
EN
Gas-based direct reduction and magnetic separation process was applied in treating a high-phosphorus oolitic iron ore, of which phosphorus mainly occured as Fe3PO7 and apatite. The mechanism of CaCO3 was investigated using XRD, SEM-EDS, and mineral phase analysis. Results showed that when no CaCO3 was added, most of the iron minerals were reduced to metallic iron, while Fe3PO7 was reduced to elemental phosphorus and mixed with the metallic iron particles. When a small amount of CaCO3 was added, CaCO3 preferentially reacted with SiO2, Al2O3 and other components, preventing them from reacting with FeO and resulting in the increase of iron recovery. When the amount of CaCO3 reached 25%, apatite was produced from the reaction of CaO and Fe3PO7, which could be later removed by grinding and magnetic separation.
2
Content available Effect of direct reduction time of vanadium titanomagnetite concentrate on the preparation and photocatalytic performance of calcium titanate
Li Xiaohui, Kou Jue, Sun Tichang, Wu Shichao, Tian Yuechao
Physicochemical Problems of Mineral Processing
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2021
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Vol. 57, iss. 1
75--86
EN
Effects of direct reduction time of vanadium titanomagnetite concentrate (VTCE) on the preparation and photocatalytic performance of calcium titanate were investigated in this study. It was found that extending the reduction time could not only promote the formation of calcium titanate, but also facilitate the reduction of iron minerals in the reduction products. The optimum reduction time was 180min under the conditions of CaCO3 dosage of 18wt%, reduction temperature of 1400℃ and lignite dosage of 70wt%. The reduced iron (Fe grade of 90.95wt%, Fe recovery of 92.21wt%) and calcium titanate were obtained via grinding-magnetic separation. Moreover, calcium titanate prepared via the direct reduction method could be used as a photocatalyst, where the degradation degree of methylene blue increased from 25.13% to 60.14% with the addition of calcium titanate. Furthermore, Langmuir Hinshelwood fitting results indicated that the degradation of methylene blue by the calcium titanate prepared under different reduction times conformed to first-order reaction kinetics, where the photocatalytic degradation rate of methylene blue was noted to be the highest for a reduction time of 180 min.
3
Content available Feasibility study on preparation of magnesium titanate in carbonthermic reduction of vanadium titanomagnetite concentrates
Chen Chao, Sun Ti-Chang, Kou Jue, Wang Xiao-Ping, Zhao Yong-Qiang
Physicochemical Problems of Mineral Processing
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2019
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Vol. 55, iss. 2
417--425
EN
Effect of temperature and Mg:Ti ratio on phase composition and microstructure of reduced pellets was investigated to verify the feasibility of preparation of magnesium titanate by adding MgO in carbonthermic reduction of the vanadium titanomagnetite concentrates (VTC). Thermodynamic analysis results showed that magnesium titanate is more easily generated than FeTi2O5 or TiO2 by the reaction of FeTiO3 and MgO under the reductive atmosphere, which was confirmed by the discovery of magnesium titanate at roast experiment. It was found that the optimum conditions for reduction of VTC pellets were temperature of 1250 ºC and Mg:Ti ratio of 2, and the main phases of reduction product were metallic Fe and magnesium titanate (Mg2TiO4). However, trace iron impurities in Mg2TiO4 particles were found by energy-dispersive spectroscopy (EDS), so further purification is required.
4
Content available Effects of Temperature on Fe and Ti in Carbothermic Reduction of Vanadium Titanomagnetite with adding MgO
Li Xiaohui, Kou Jue, Sun Tichang, Wu Shichao, Zhao Yongqiang
Physicochemical Problems of Mineral Processing
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2019
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Vol. 55, iss. 4
917--927
EN
Effects of temperature on Fe and Ti in carbothermic reduction of vanadium titanomagnetite (VTM) concentrate with adding MgO at 1100~1500℃ were investigated. It was found that most of Fe in the VTM concentrate existed in the form of magnetite and a small amount existed as ilmenite; Ti in the VTM concentrate was mainly present in the form of ilmenite. The temperature had significant effects on Fe and Ti: increasing temperature was beneficial to decrease the Fe content in the magnesium titanate mixture, and the Fe content could decrease to 5.47% at 1500℃. Thermodynamic analysis showed that FeTiO3 and MgO preferentially reacted to form Mg2TiO4, followed by MgTiO3 and MgTi2O5 when the temperature increased from 1100℃ to 1500℃. Results of X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy analyzes showed that an intermediate product of MgFe2O4 would formed at 1300~1400℃ in the actual experiment. This caused the Fe content in the magnesium titanate mixture to increase from 21.32% to 22.85% when the temperature increased from 1200℃ to 1400℃. In addition, the size of magnesium titanate particles could increase from a few microns to approximately 100 µm when the temperature increased from 1100℃ to 1500℃, which was conducive to realize the separation of metallic iron and magnesium titanate.
5
Content available Application of superconducting magnetic separation to an artificial mixture of chalcopyrite and molybdenite
Li Daokui, Kou Jue, Sun Chunbao, Yu Baoqiang, Wang Chao
Physicochemical Problems of Mineral Processing
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2019
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Vol. 55, iss. 3
597--604
EN
Superconducting magnetic separation of chalcopyrite and molybdenite was studied, along with the effects of the magnetic flux density, slurry concentration, and pulsation amplitude on the separation. According to the force equilibrium model of magnetic particles that accumulated on magnetic matrices during the superconducting magnetic separation, the saturated buildup of magnetic particles was calculated. The saturated buildup of magnetic particles was an approximate fan ring and had a positive correlation with the background magnetic flux density. Superconducting magnetic separation tests results showed that a Mo concentrate with a Mo grade of 31.86% and recovery of 87.24% and a Cu concentrate with a Cu grade of 30.57% and recovery of 94.76% could be obtained. This verified the feasibility of separating mixed Cu and Mo minerals via superconducting magnetic separation.
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