电炉法制磷过程热力学及动力学分析

Thermodynamics and kinetics analysis of phosphorus production by electric-furnace method

采用FactSage软件对电炉法制磷过程中的渣系相图进行计算,并对体系内相关组分的助熔效果进行了分析。考察了不同温度下PO的还原率差异,并对反应过程进行了热力学和动力学分析。结果表明,当酸度值M为0.75~0.85时,AlO含量对体系形成低共熔物及调节低共熔温度存在一定影响,且适当增大AlO含量对电炉法制磷过程更有利。单一添加MgO作助熔剂不能有效促进炉料熔融,且会使共熔温度升高,因此应考虑与其他助熔剂复配使用。磷矿熔融还原反应符合一级反应特征,体系的表观活化能为165.712 k J/mol。

Yellow phosphorus is an importan industrial raw material for the development of phosphorus chemical industry in China. The yellow phosphorus production by electric-furnace method has always been the core of thermal process for phosphate rock treatment. The electric-furnace method should be able to make direct use of the low-grade phosphate rocks, especially those with high silicon content, but this would consume a lo of energy. The researchers note that attention should be given to the formation of eutectic and the adjustment of eutectic temperature. A large number of experimental studies are obtained to discuss the macroscopic effect of different strengthening means of phosphate rock reduction. However, the mechanism is mostly inferred. At present, the lack of objective presentation of the eutectic composition and transformation hinders the clear explanation of those mechanisms. Thus, it is necessary to study the phase diagram of slag and the melting aid effect in the phosphorus production process by means of chemical thermodynamics computation. It is of great realistic and scientific significance to reveal the interaction mechanism and improve an electric-furnace technology of phosphorus production. In this work, the phase diagram and melting mechanism in the phosphorus production process by electric-furnace method were studied with FactSage 8.0 computation. It showed that levels of AlOhad a certain effect on the formation of eutectic and the adjustment of eutectic temperature. With the proper increase of AlOcontent, the phosphorus production process was improved. In contrast, the single MgO as a flux was unable to effectively promote the charge melting and the eutectic temperatures were likely to rise. Beyond these points, the melting reduction reaction of the phosphate rock was demonstrated to be consistent with the first-order reaction characteristics.