真空条件下硅热还原CaO·MgO冶炼金属镁的动力学机理

来源期刊:中国有色金属学报(英文版)2020年第10期

论文作者:车玉思 买耕鹏 李少龙 何季麟 宋建勋 易健宏

文章页码:2812 - 2822

关键词:镁冶炼;非等温动力学;等转化率法;动力学机理

Key words:magnesium production; non-isothermal kinetics; iso-conversional method; kinetic mechanism

摘    要:采用自行研制的热重分析仪(TGA),在真空和高温条件下对硅热还原CaO·MgO进行研究。采用1.5、2.0、2.5和3.0 °C/min升温速率分别测定由煅烧白云石、硅铁和萤石制成球团在5 Pa真空和300~1400 °C条件下的热重损失。选择无模式函数法与模式函数法对还原过程的动力学机理进行模拟计算,综合分析热重曲线在反应起始段与结束段的形状特性、微分热重的半宽比和动力学参数,最终得出还原反应的最概然机理函数是一阶化学反应模式函数,其活化能与指前因子分别为233.42 kJ/mol和5.14 × 1010 s-1。该项研究工作为真空条件下硅热法炼镁提供了基础动力学数据。

Abstract: The investigation of silicothermic reduction of CaO·MgO was carried out using a self-developed thermogravimetric analysis (TGA) instrument under vacuum and high temperature conditions. The TG data of pellets prepared with calcined dolomite, ferrosilicon and fluorite were determined at the heating rates of 1.5, 2.0, 2.5 and 3.0 °C/min in 5 Pa vacuum at 300-1400 °C, respectively. Model-free analysis and model-based analysis were applied for simulating the kinetic mechanism. By analyzing the characteristics of the initial and final reaction temperatures of TG curve, ratio of half-width of derivative TG curve and kinetic parameters, a conclusion was made that the most probable mechanism function is the first order formal chemical reaction with activation energy of 233.42 kJ/mol and pre-exponential factor of 5.14×1010 s-1. This study provides the basic data of dynamics of silicothermic magnesium production under vacuum conditions.

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