清平磷矿的硝酸分解动力学研究

Kinetics of Decomposition of Qingping Phosphate Rock with Nitiric Acid

在间歇反应器中,反应温度为30～60℃,硝酸初始浓度30%～54%,磷矿初始粒径0.1875～0.5375mm,搅拌强度400r/min的条件下研究了硝酸分解磷矿的反应过程机理及宏观动力学。结果表明,磷矿分解速率及转化率随着搅拌强度、反应温度、硝酸浓度和颗粒细度的增加而增加;氢离子通过液膜的扩散传质是该过程的速率控制步骤。并应用固体粒径减小的缩芯模型,将上述各影响因素的实验数据进行拟合,得到了硝酸分解磷矿的宏观动力学模型。其活化能Ea=6.198kJ/mol,属液膜扩散传质控制。

In this paper,a study on reaction mechanism and macrokinetics of decomposition of phosphate rock with nitric acid in a batch reactor was described.The reaction temperature was selected from 30 to 60℃,initial nitric acid concentration varies from 30 to 54wt%,initial mean particle size is 0.18 to 0.53mm,and the stirred speed is 400r/min.The experimental results showed that the decomposition rate and conversion ratio is increased with increase in stirred speed,reaction temperature,initial nitric acid concentration and fineness of the particule.Meanwhile,the diffusion of hydrogen ions through the liquid film is ratecontrolling step of the decomposion process.By use of the shrinking core models,the experimental data was fitted to a kinetic model for the decomposition process,a microkinetic model for decomposition of phosphate rock with nitric acid was obtained. The apparent activation energyEa is 6.198kJ/mol,therefore,the process is a liquid film diffusioncontrolling process.