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1
Content available Thermodynamics and Kinetics Analysis on Carbothermic Reduction of Calcined Magnesite in Vacuum
Tang Qifeng, Ao Jinqing, Peng Biyou, Guo Biao, Yang Tao
Archives of Metallurgy and Materials
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2022
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Vol. 67, iss. 3
1021--1026
EN
The carbothermic reduction of calcined magnesite in vacuum was studied. By thermodynamic analysis, the starting temperature of reduction reaction dropped from 2173 K to 1523 K when system pressure dropped from 1 atmosphere to 100 Pa. The experiments were carried out at different conditions under 10~100 Pa and the experimental results shown that the reduction extent of MgO improved by increasing the reaction temperature and time, the pellet forming pressure as well as adding fluoride as catalyst. The rate-determining step of carbothermic reduction process was gas diffusion with the apparent activation energy of 241.19~278.56 kJ/mol.
2
Content available Effect of mechanical activation on carbothermic reduction and nitridation of titanomagnetite concentrates
Wen Xiaojin, Yu Wen, Zeng Danliang, Zhu Liang Liang, Chen Jiangan
Physicochemical Problems of Mineral Processing
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2021
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Vol. 57, iss. 5
33--45
EN
The carbothermic reduction and nitridation process of titanomagnetite concentrates with the help of mechanical activation were investigated by particle size analysis, thermodynamic calculation, thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive spectroscopy analysis. The thermogravimetric and X-ray diffraction results indicated that either the reduction of iron oxide or the reduction and nitridation of M3O5 to TiN could be promoted significantly with the increase in activation time. The results obtained from scanning electron microscopy and energy-dispersive spectroscopy showed that, when samples were not activated, chunks of and thin M3O5 were derived from the reduction of ilmenite and titanomagnetite. They were severely sintered with impurities to form a dense structure. As a result, M3O5 was difficult to be converted to TiN, especially chunks of M3O5. However, when samples were activated, the sintering degrees of the impurity and M3O5 were mitigated, and the particle size of the iron as a medium for delivering C to M3O5 was decreased in the roasted product. This condition enhanced the diffusion of C to the surface of M3O5. Meanwhile, the bulk of ilmenite was broken in the activation process, which prevented the formation of chunks of M3O5. Thus, the conversion of M3O5 to TiN was promoted.
3
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.
4
Content available Recovery of Iron from Copper Slag by Carbothermic Reduction and Magnetic Separation in the Presence of CaO
Chun T., Mu G., Di Z., Long H., Ning C., Li D.
Archives of Metallurgy and Materials
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2018
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Vol. 63, iss. 1
299--305
EN
The carbothermic reduction of copper slag at the different binary basicity (CaO/SiO2 ) was carried out for recovering iron by wet magnetic separation. Calcium carbonate is found to be capable of improving the iron recovery, as well as increasing the particle size of metallic iron significantly. Experimental evidence showed that CaO reacted with SiO2 to form calcium silicate and FeO was liberated from the 2FeO.SiO2 , decreased the content of Fe in the slags, which improved the iron recovery during the magnetic separation. The final product, assaying 90.23%Fetotal (representing a metallization degree of 93.94%) and 0.58% Cu at the iron recovery of 85.70% was achieved at the basicity of 0.60, which can be briquetted as a burden material for weathering resistant steel making by electric arc furnace to replace part of scrap.
5
Content available Recovery Of Valuable Metals In Tin-Based Anodic Slimes By Carbothermic Reaction
Han C., Kim Y.-M., Son S. H., Choi H., Kim T. B., Kim Y. H.
Archives of Metallurgy and Materials
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2015
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Vol. 60, iss. 2B
1213--1216
EN
This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail of carbothermic reaction, thermodynamic calculation was carried out and compared with experiments. From thermodynamic calculation and experiment, it was confirmed that Sn-based anodic slime could be reduced by controlling temperature and amount of carbon. However, any tendency between the reduction temperature and carbon content for the reduction reaction was not observed.
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