Abstract
Metallic magnesium was prepared by vacuum-assisted carbothermic reduction method, and its morphologies were observed and analyzed. The reduction ratios of reactions were carried out under various vacuums, reaction temperatures, and time. Reaction kinetics of carbothermic reduction process was investigated. The results reveal that the morphologies of metallic magnesium sample that crystallized in the bottom and top sections of the condensation cap appear as the shape of feather with close-packing needle structure and the shape of schistose with metal luster, compactly clumpy structure, respectively. The reduction ratio of reaction process can be facilitated through reducing vacuum, increasing temperature, lengthening time, or their combinations and can reach up to 83.7 % under the condition of 10 Pa and 1573 K with 60 min reaction time. At 1423–1573 K, the reaction rate constant k of carbothermic reduction of magnesia in vacuum gets greater with the increase of temperature. The reaction activity energy is 190.28, 219.71 and 451.12–528.54 kJ·mol−1 when the procedure of carbon gasification reaction, interfacial reaction, or gaseous diffusion is the reaction rate-determining step at 1423–1573 K, respectively. The gaseous diffusion procedure has the largest activity energy value and is, therefore, the main reaction rate-determining step.
Similar content being viewed by others
References
Dai YN, Yang B. Vacuum Metallurgy of Nonferrous Metals. Beijing: Metallurgical Industry Press; 2000. 294.
Noboru Y, Etsuko I, Ken-ichi M, Shoji T. Difference in carbo-thermal reduction reaction kinetics of NiO in microwave E- and H-fields. Mater Lett. 2007;61(10):2096.
Sondhi A, Morandi C, Reidyn RF, Scharf TW. Theoretical and experimental investigations on the mechanism of carbothermic reduction of zirconia. Ceramics Int. 2013;39(4):4489.
Hu FP, Pan J, Ma X, Zhang X, Chen J, Xie WD. Preparation of Mg and Ca metal by carbothermic reduction method-a thermodynamics approach. J Magnes Alloy. 2013;1(3):263.
Hansgirg FJ. Thermal reduction of magnesium compounds. Iron Age. 1943;152(21):56.
Winand RM, van Gysel, Fontana A, Segers L, Carlier JC. Production of magnesium by vacuum carbothermic reduction of calcined dolomite. Trans Instn Min Metall Sect C.1990; 99(May–Aug.):C105.
Yu QC, Yang B, Ma WH, Li ZH, Dai YN. Study of carbothermic reduction of magnesia in vacuum. Chin J Vacuum Sci Technol. 2009;29(S):68.
Abraham MC, Ghosh A. Kinetics of reduction of iron oxide by carbon. Iron Mak Steel Mak. 1979;6(1):14.
Yang CB, Tian Y, Qu T, Yang B, Xu BQ, Dai YN. Production of magnesium during carbothermal reduction of magnesium oxide by differential condensation of magnesium and alkali vapours. J Magnesium Alloy. 2013;1(4):323.
Gruner W, Stolle S, Berger LM, Wetzig K. A new experimental approach for accelerated investigations of carbothermic reactions. Int J Refractory Met Hard Mater. 1999;17(1–3):227.
Xie WD, Wang H, Hu FP, Li ZN, Peng XD. Vacuum carbothermic reduction kinetics of strontium oxide. Chin J Rare Met. 2013;37(2):260.
Xie WD, Zhang X, Hu FP, Wei GB, Peng XD, Wang H, Ma X, Pan J. Approach of magnesium prepared by carbothermic reduction of magnesium mineral, Chinese Patent, 201310162758.0, 2013.
Zhai XL, Zhang Y. Study of the thermal decomposition mechanism of Taihangshan dolomite. Acta Mineral Sinica. 2000;20(2):160.
Xie WD, Dang CM, Li ZN, Peng XD, Wang H. Preparation of Mg using Si-Cu reduction and its thermodynamics. Chin J Rare Met. 2012;36(2):213.
Huang DB, Yang XM, Yang TJ. Kinetics and mathematical model for reduction process of iron ore briquette containing carbon. Acta Metallurg Sinice. 1996;32(6):630.
Liang Z, Tsai HL. Reduction of solid–solid thermal boundary resistance by inserting an interlayer. Int J Heat Mass Transf. 2012;55(11–12):2999.
Boris VL, Valery LU. Kinetics of free-surface decomposition of dolomite single crystal and powders analyzed thermogravimetrically by the third-law method. Thermochim Acta. 2003;401(2):139.
Xie WD, Wang H, Hu FP, Li ZN, Peng XD. Vacuum carbothermic reduction kinetics of strontium oxide. Chin J Rare Met. 2013;37(2):260.
Li RT, Pan W, Sano M, Li JQ. Kinetics of reduction of magnesia with carbon. Thermochim Acta. 2002;390(1–2):145.
Busenberg E, Plummer LN. The kinetics of dissolution of dolomite in CO2-H2O systems at 1.5 to 65°C and 0 to 1 atm \({\text P}_{{\text {CO}_2}}\). Am J Sci. 1982;282(1):45.
Huang BH, Lu WK. Kinetics and mechanism of reaction in iron ore/coal composites. IS IJ Int. 1993;33(10):1055.
Jiang WL, Deng Y, Yang B, Liu DC, Dai YN, Xu BQ. Application of vacuum distillation in refining crude indium. Rare Met. 2013;32(6):627.
Zaldívar-Cadena AA, Díaz-Peña I, Cabañas-Moreno JG. Dispersion of niquel on the microstructure in magnesium based alloys for hydrogen storage. J Magnesium Alloy. 2013;1(4):292.
Wang QH, Shao JH, Lin YH, Guo ZC, Tang HQ. An experimental study on the kinetics of iron fine reduced by CO in micro fluidized bed. J Iron Steel Res. 2012;24(4):6.
Acknowledgments
This study was financially supported by the National Basic Research Program of China (No. 2007CB613700) and the International Scientific and Technological Cooperation Program (No. 2010DFR50010).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Xie, Wd., Chen, J., Wang, H. et al. Kinetics of magnesium preparation by vacuum-assisted carbothermic reduction method. Rare Met. 35, 192–197 (2016). https://doi.org/10.1007/s12598-014-0275-6
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12598-014-0275-6