低品位磷矿热解还原过程机理研究

Study on the Mechanism of Pyrolysis Reduction Process of Low-Grade Phosphate Rock

本文以低品位磷矿为实验原料,分析纯二氧化硅为助熔剂,焦炭为还原剂,在1250℃下反应不同时间,计算磷矿还原率,并对反应后的残渣状态和物相组成进行分析。结合FactSage热力学软件,对反应历程及过程中可能发生的反应进行理论验证。结果表明脱氟反应是磷矿热解还原反应的第一步,形成磷酸钙和硅酸钙,此反应也是磷矿热解还原反应过程的控制步骤。硅钙比在一定程度内的增加有利于脱氟反应的进行,从而提高磷矿还原率。本研究系统研究了磷矿热解还原过程机理,为解决热法磷酸能耗大的问题提供了依据。

Using low-grade phosphate rock as the experimental raw material, analyzing pure silica as the flux, coke as the reducing agent, reacting at 1250˚C for different times, the reduction rate of phosphate rock is calculated, and the state of residue and phase composition after the reaction are analyzed. Combined with FactSage thermodynamics software, the theoretical verification of the reaction history and possible reactions in the process was carried out. The results showed that the defluorination reaction, forming calcium phosphate and calcium silicates, is the first step and also the control step of the pyrolysis and reduction of phosphate rock. The increase of silicon-calcium ratio is conducive to the defluorination reaction to a certain extent, which could improve the phosphate rock reduction rate. The mechanism of the pyrolysis reduction process of phosphate rock has been studied in this paper, which provides a basis for solving the problem of large energy consumption of thermal phosphoric acid.