真空碳热还原煅白的热力学分析  

Thermodynamic Analysis of Mg Extraction from Calcined Dolomite by Carbothermic Reduction in Vacuum

作　　者：王昱超[1,2,3] 田阳[1,2,3] 杨成博[1,2,3] 杨斌[1,2,3] 曲涛[1,2,3] 戴永年[1,2,3] 王刚[1,2,3] 

机构地区：[1]真空冶金国家工程实验室,昆明650093 [2]昆明理工大学冶金与能源工程学院,昆明650093 [3]云南省有色金属真空冶金重点实验室,昆明650093

出　　处：《真空科学与技术学报》2013年第11期1144-1150,共7页Chinese Journal of Vacuum Science and Technology

基　　金：云南省应用基础研究计划面上项目(S2012FZ0110);昆明理工大学校级人培项目;云南省应用基础研究计划(No.2011FB040)

摘　　要：本文对煅白真空碳热还原法制取镁反应过程进行了热力学分析,在系统压力30~100 Pa,还原温度1573 K条件下,C与MgO反应生成镁蒸气;温度达到1667 K时,C与CaO反应生成CaC2,在此温度条件下,CaC2也可与MgO反应生成镁蒸气。因此,煅白真空碳热还原法制取镁的过程,除了C直接还原MgO,还有C还原CaO生成CaC2参与还原反应制取镁。另外,通过热力学计算,真空条件下,碳热还原过程中3CaO·SiO2,2CaO·SiO2,SiC和CaS是可以产生的,而煤中的硫酸钙和单质硫主要参与了生成CaS的反应。实验结果分析表明：3CaO·SiO2,2CaO·SiO2,SiC和CaS产物的生成与剩余物的X射线衍射（XRD）分析相吻合,验证了热力学计算的正确性。通过对冷凝物的XRD分析,冷凝物中大部分为Mg,有少部分的MgO是由于金属Mg和CO蒸气发生逆反应所得。We addressed the possible mechanisms responsible for extraction of Mg from the calcined dolomite by carbothermic reduction in vacuum. According to thermodynamics calculation,at a pressure in the 30 - 100 Pa range and at 1573 K,Mg vapor forms because of the reaction of C and MgO; at 1667 K,the CaC2emerges,due to the reaction of C and CaO,and effectively reduces MgO to produce Mg vapor,accompanied by the direct reduction of MgO by C. In addition,several compds,including 3Cao·SiO2,2CaO·SiO2,SiC and CaS,were found to co-exist. The sulfur and sulfate impurities in coal participate in the CaS formation. The resultants and slag were characterized with X-ray diffraction. The XRD spectra agreed fairly well with the calculated results. A tiny fraction of MgO,found in the Mg condensate,possibly originated from the reverse reaction of CO and Mg vapor,there.

关 键 词：真空冶金 热力学 碳热还原 煅白 金属镁 

分 类 号：TF131[冶金工程—冶金物理化学] TF822