氟磷酸钙真空碳热还原反应机理

Carbothermal reduction mechanism of fluorapatite in vacuum

在真空条件下,本文采用热力学分析、XRD及化学分析等方法与手段,对SiO2在氟磷酸钙碳热还原制磷的过程进行了研究,考察了SiO2的添加量对磷矿还原率的影响。通过热力学研究,在压力100 Pa温度低于1075℃时,Ca5(PO4)3F与C、SiO2的反应满足反应发生的热力学条件。实验研究表明:在真空度10 Pa^80 Pa,温度达到实验最高温度1550℃时,二氧化硅不能使氟磷酸钙发生脱氟反应,与热力学计算结果一致。还原率随着温度升高而增大,在低于1450℃时,添加SiO2有利于提高还原率;随m增加,还原率也增加,在1350℃时,还原率增大速度较快。由此作者提出了SiO2对氟磷酸钙真空碳热还原的反应机理。

The influence of SiO2 content on the reduction rate of phosphate during fluorapatite carbothermal reduction process was investigated by thermodynamic analysis, XRD and element analysis in vacuum. Thermodynamic calculations indicated that reaction between Cas（PO4）3F.C and SiO2 occurred below 1075℃ at 100Pa. Experimental results demonstrated that defluorination of the silica and fluorapatite can＇t occur at 1550℃ under 10Pa-80Pa. Reduction rate increases with the increasing temperature, and the added SiO2 help to improve the reduction rate below 1450℃ ;As m increases, the reduction rate increasesd, especially at 1350℃. Thus, the reaction mechanism of SiO2 on fluorapatite carbothermal reduction in vacuum was proposed.