氯化焙烧铜熔炼渣的过程机理及动力学

Mechanism and kinetics for chlorination roasting of copper smelting slag

提出一种以CaCl_(2)为氯化剂,采用氯化焙烧法从铜熔炼渣中高效回收锌的工艺。利用热力学计算、热重–差热(TG-DSC)分析和X射线衍射(XRD)等手段,研究氯化反应机理和氯化焙烧过程动力学。结果表明,CaCl_(2)氧化分解和所有含锌相的氯化反应温度均分别高于774.3和825℃。铜熔炼渣的氯化焙烧过程可分为4个阶段,依次为吸附水脱除、结晶水脱除、含铁相氧化和锌的氯化挥发。铁氧化阶段和锌氯化挥发阶段的表观活化能分别为101.70和84.4 k J/mol,铁氧化过程的最概然机理函数为Avrami–Erofeev方程(n=2),锌氯化过程符合未反应核收缩模型且受化学反应控制。

An efficient process based on chlorination roasting with CaCl_(2)was proposed to recover zinc from copper smelting slag.The reaction mechanism and the kinetics of the chlorination process were investigated by thermodynamic calculation,thermogravimetry and differential scanning calorimetry(TG-DSC)analysis and X-ray diffraction(XRD)methods.The results demonstrated that the temperatures of oxidative decomposition of CaCl_(2)and chlorination of all Zn-containing phases were above 774.3 and 825°C,respectively.The chlorination roasting process was divided into four stages:precipitation of adsorbed water,extraction of crystallized water,oxidation of Fe-containing phases,and chlorination volatilization of zinc.The average apparent activation energies of the iron oxidation and zinc chlorination were 101.70 and 84.4 k J/mol,respectively.The most probable mechanism function for the iron oxidation process was the Avrami-Erofeev model(n=2).Zinc chlorination followed the shrinking unreacted core model,and the chemical reaction was the rate-controlling step.