机械力-微波活化对稀土尾矿NH3-SCR脱硝性能的影响

Effect of mechanical force and microwave on the NH_(3)-SCR denitration of rare earth tailings

因为稀土尾矿中矿物复杂的连生关系,使其部分矿物在脱硝反应过程中并不能充分暴露发挥作用。本文采用机械力微波活化稀土尾矿,利用正交试验方法研究机械力微波活化参数对稀土尾矿NH_(3)-SCR脱硝性能的影响,借助XRD、SEM-EDS、H_(2)-TPR、NH_(3)-TPD、BET等表征手段分析了机械力微波活化对稀土尾矿性能的影响。实验结果表明,稀土尾矿对活化参数的敏感性为:球料比>转子转速>球磨时间=球直径比>微波焙烧时间=微波焙烧温度=微波焙烧功率,机械力微波活化最优参数为球磨2h、转子转速300r/min、球料比1∶1、球直径比1∶1∶1、微波焙烧温度250℃、微波焙烧时间20min、微波焙烧功率1100W,活化稀土尾矿脱硝效率最高提升了40%。活化后,稀土尾矿催化剂的比表面积、矿物分散度、表面酸性位数量和氧化还原性能均得到了提升,弱酸、中强酸和强酸活性中心均匀分布有利于脱硝反应。赤铁矿暴露程度越高,越有利于稀土尾矿脱硝反应过程。

Due to the complex association of minerals in rare earth tailings,some minerals cannot be fully exposed to show their activity.In the paper,rare earth tailings were activated by the combination of mechanical force and microwave.Orthogonal test was used to study the effects of operation parameters of mechanical force and microwave activation on the NH_(3)-SCR denitration performance,with the aid of characterization methods of XRD,SEM-EDS,H_(2)-TPR,NH_(3)-TPD,and BET.The results showed that the significance of the parameters was in the order:ball to powder weight ratio>rotor speed>ball milling time=ball diameter ratio>calcination temperature=calcination time=calcination power.The optimum activation parameters were determined as powder weight ratio was 1∶1,rotor speed was 300r/min,ball milling time was 2h,ball diameter ratio was 1∶1∶1,calcination temperature was 250℃,calcination time was 20min,and calcination power was 1100W,under which the denitration activity of rare earth tailings increased by 40%.The specific surface area,mineral dispersion,amount of surface acid active site and redox performance of rare earth tailings can be improved.The uniform distribution of weak,medium to strong and strong acid active sites is beneficial to the denitration activity.The high degree of hematite exposure is conducive to the denitration of rare earth tailings.