The high-temperature volatilization behavior of the SnO–SiO₂ and SnO–CaO–SiO₂ slag systems was studied by simultaneous thermal analysis. The volatilization characteristics of the two systems with different SnO contents and different heating rates were discussed, and the kinetic parameters, reaction mechanism, and thermodynamic parameters of the volatilization reaction of the slag system at high temperature were calculated. The results of thermal analysis show that the volatilization of tin slag at high temperature is related to the activity of SnO and the decomposition of stannous silicate in tin slag. The slag system has obvious volatilization effect when the content of SnO is more than 60% in the SnO–SiO₂ binary slag system. When CaO is added into the binary slag system, the volatilization of slag system becomes easier. The volatilization rate decreases with increasing heating rate. The volatilization kinetic parameters and mechanism functions of the SnO–SiO₂ and SnO–CaO–SiO₂ systems were calculated by Coats–Redfern and Achar–Brindley–Sharp–Wendworth methods. It is concluded that the volatilization of tin slag at high temperature is controlled by three-dimensional diffusion mechanism. The mechanism function is Jander equation with integral form of [1 − (1 − α)^1/3]² and the differential form of 3/2(1 − α)^2/3[1 − (1 − α)^1/3]⁻¹. The rate constants of the SnO–SiO₂ and SnO–CaO–SiO₂ systems are \(k\, = \,1.36\, \times \,10^{16} \,\exp \,\left( {{{ - \,61408.61} \mathord{\left/ {\vphantom {{ - \,61408.61} T}} \right. \kern-\nulldelimiterspace} T}} \right)\) and \(k\, = \,1.61\, \times \,10^{17} \,\exp \,\left( {{{ - \,64869.66} \mathord{\left/ {\vphantom {{ - \,64869.66} T}} \right. \kern-\nulldelimiterspace} T}} \right)\), and the isokinetic temperatures are 1174.4 and 1208.3 °C, respectively. Finally, the thermodynamic parameters of the slag system in the high-temperature volatilization process are discussed. The activation enthalpy ΔH of the SnO–SiO₂ and SnO–CaO–SiO₂ systems is 498.33 and 526.96 kJ/mol, respectively. The activation Gibbs free energy ΔG is 436.56 and 433.87 kJ/mol, and the activation entropy ΔS is 42.66 and 62.84 J/(mol K), respectively.

Graphical Abstract

中文翻译：

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SnO-SiO2和SnO-SiO2-CaO体系挥发动力学研究

通过同步热分析研究了SnO-SiO ₂和SnO-CaO-SiO ₂渣体系的高温挥发行为。讨论了不同SnO含量和不同升温速率的两种体系的挥发特性，计算了渣体系高温挥发反应的动力学参数、反应机理和热力学参数。热分析结果表明，锡渣在高温下的挥发与锡渣中SnO的活性和硅酸亚锡的分解有关。_{SnO-SiO 2}中SnO含量大于60%时渣系有明显的挥发作用二元炉渣系统。在二元渣体系中加入 CaO 后，渣体系的挥发变得更容易。挥发率随着加热速率的增加而降低。采用 Coats-Redfern 和 Achar-Brindley-Sharp-Wendworth 方法计算了 SnO-SiO ₂和 SnO-CaO-SiO ₂体系的挥发动力学参数和机理函数。得出结论，锡渣在高温下的挥发受三维扩散机制控制。机理函数为 Jander 方程，积分形式为 [1 - (1 -  α ) ^1/3 ] ²，微分形式为 3/2(1 -  α ) ^2/3 [1 - (1 -  α )^1/3 ] ^-1。_{SnO–SiO 2}和 SnO–CaO–SiO ₂体系的速率常数为\(k\, = \,1.36\, \times \,10^{16} \,\exp \,\left( {{{ - \,61408.61} \mathord{\left/ {\vphantom {{ - \,61408.61} T}} \right. \kern-\nulldelimiterspace} T}} \right)\)和\(k\, = \, 1.61\, \times \,10^{17} \,\exp \,\left( {{{ - \,64869.66} \mathord{\left/ {\vphantom {{ - \,64869.66} T}} \right . \kern-\nulldelimiterspace} T}} \right)\)，等速温度分别为 1174.4 和 1208.3 °C。最后，讨论了炉渣系统在高温挥发过程中的热力学参数。_{SnO–SiO 2}和 SnO–CaO–SiO ₂的活化焓 ΔH系统分别为 498.33 和 526.96 kJ/mol。活化吉布斯自由能 ΔG 为 436.56 和 433.87 kJ/mol，活化熵 ΔS 分别为 42.66 和 62.84 J/(mol K)。

图形概要