Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报(英文版)

Transactions of Nonferrous Metals Society of China

Vol. 24    No. 8    August 2014

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Mechanism of extracting magenesium from mixture of calcined magnesite and calcined dolomite by vacuum aluminothermic reduction
Da-xue FU, Yao-wu WANG, Jian-ping PENG, Yue-zhong DI, Shao-hu TAO, Nai-xiang FENG

School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China

Abstract:The process of aluminothermic reduction of a mixture of calcined dolomite and calcined magnesite had been developed. The mechanism of the process was studied by SEM and EDS. The reduction process was divided into three stages: 0≤ηtf≤0.43±0.06, 0.43±0.06≤ηtf≤0.9±0.02 and 0.9±0.02≤ηtf <1, where ηt and ηf are the reduction ratio at time t and the final reduction ratio obtained in the experiment at temperature T, respectively. The first stage included the direct reaction between calcined dolomite or calcined magnesite and Al with 12CaO·7Al2O3 and MgO·Al2O3 as products. The reaction rate depended on the chemical reaction. The CA phase was mainly produced in the second stage and the overall reaction rate was determined by both the diffusion of Ca2+ with molten Al and the chemical reaction. The CA2 phase was mainly produced in the third stage and the reaction process was controlled by the diffusion of Ca2+.

 

Key words: magnesium; aluminothermic reduction; magnesite; dolomite; mechanism

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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