摘要
为探明电炉法黄磷的反应历程,采用纯物质模拟电炉法黄磷生产,并使用HSC热力学软件、X射线衍射(XRD)、扫描电子显微镜(SEM)等分析方法对该过程进行辅助研究。HSC和XRD分析结果表明氟磷灰石碳热还原反应历程如下:Ca_5(PO_4)_3F优先与SiO_2发生脱氟反应生成Ca_3(PO_4)_2,而Ca_3(PO_4)_2又被碳还原产生CaO,并结合SiO_2形成钙硅酸盐,而F最终以SiF_4(g)的形式排出体系;动力学分析结果表明氟磷灰石的碳热还原反应是一个变级反应,反应级数随温度升高而降低,反应速率随温度升高而增大,随时间增大而降低,其反应活化能为188.96 kJ×mol~(-1),表明是一个高能耗反应;渣相SEM分析结果表明随着温度的升高,体系的液相逐渐增多,物质扩散加快,导致反应速率增大,这与动力学分析结果相一致。
In order to investigate yellow phosphorus production in electric furnace, pure chemicals were used to simulate this process in electric furnace. The process was studied by HSC thermodynamics software, X-ray diffraction(XRD) and Scanning electron microscope(SEM). Thermodynamics and XRD analysis indicate that the carbothermal reduction process of fluoroapatite is as follows: Ca_5(PO_4)_3 F is preferentially defluorinated with SiO_2 to form Ca_3(PO_4)_2, and Ca_3(PO_4)_2 is then reduced by carbon to produce CaO which combines with SiO_2 to form calcium silicate. Meanwhile, F is discharged in the form of SiF_4(g). Kinetic analysis shows that the carbothermal reduction reaction is a graded reaction. Reaction order decreases with the increase of temperature.The reaction rate increases with temperature and decreases with time. The activation energy is 188.96 k J×mol~(-1),which indicates that it is a highly energy-consuming reaction. SEM analysis of slag phase shows that liquid phase of the system gradually increases with the increase of temperature, which accelerates diffusion and increases the reaction rate. This trend is consistent with the results of kinetic analysis.
引文
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