硅热法提磷非等温动力学分析研究

    Analytical Study on Non-isothermal Kinetics of Phosphorus Extraction by Silica Thermal Process

    • 摘要: 【目的】为开发硅热法还原磷矿粉提取黄磷的新工艺,并研究其非等温动力学行为,【方法】采用ICP-OES、XRD、SEM-EDS分析还原率、残磷量、矿相结构及形貌,并用Coats-Redfern法和Šatava–Šesták法计算活化能(Eα)与机理函数G(α)。【结果】硅热法提磷的化学反应大约在1 000 ℃开始发生,还原历程可分为两段,第一阶段是矿粉中少部分Ca5(PO4)3F与SiO2生成中间产物Ca3(PO4)2,Ca3(PO4)2再和还原剂Si发生反应;第二阶段是剩余的Ca5(PO4)3F直接与还原剂Si发生反应。由于生成磷气的逸出,反应产物产生较多气孔且反应产物为硅酸钙。【结论】硅热法提磷反应受Avrami-Erofeev成核与生长模型控制,提高升温速率可降低表观活化能,还原过程在1 000 ℃以上显著发生并经历两段反应历程。

       

      Abstract: Objective To develop a new process for extracting yellow phosphorus from phosphate rock powder by silicon thermal reduction and study its non-isothermal kinetic behavior, Method the reduction rate, residual phosphorus content, mineral phase structure and morphology were analyzed by ICP-OES, XRD and SEM-EDS. The activation energy (Eα) and mechanism function G(α) were calculated by Coats-Redfern method and statava-stestak method. Result Silicothermic reaction of phosphate ore started at about 1 000 ℃. The reduction process can be divided into two stages: the initial stage involved a small portion of Ca5(PO4)3F in the ore powder reacting with SiO2 to form the intermediate product Ca3(PO4)2, which subsequently reacted with silicon, whereas the latter stage comprised the remaining Ca5(PO4)3F reacting directly with silicon. A large number of pores were formed due to the escape of the produced phosphorous gas, and the phase was identified as calcium silicate. Conclusion The phosphorus extraction reaction by the silicon thermal method is controlled by the Avrami-Erofeev nucleation and growth model. Increasing the heating rate can reduce the apparent activation energy. The reduction process occurs significantly above 1 000 ℃ and undergoes two reaction stages.

       

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