稀土尾矿矿物学分析及微波焙烧对其催化脱硝性能的影响

Mineralogy Analysis of Rare Earth Tailings and Effect of Microwave Calcination on Their Catalytic Denitrification Performance

利用X射线荧光光谱分析仪(XRF)、X射线衍射仪(XRD)、扫描电镜(SEM)、矿物特征自动定量分析系统(AMICS)、热重-质谱联用(TG-MS)对稀土尾矿的化学组成、矿物组成、矿物嵌布特征进行研究。结果表明:稀土尾矿矿物组成复杂,嵌布粒度很细。稀土尾矿中铁元素主要赋存于赤铁矿、磁铁矿和黄铁矿中,稀土元素主要赋存于氟碳铈矿和独居石中。选取300℃、350℃、400℃、450℃和500℃五个温度对稀土尾矿进行微波焙烧处理。实验结果显示,经过400℃焙烧后的稀土尾矿催化脱硝率最高,当反应温度为900℃时,脱硝率可达96.1%。对经过400℃微波焙烧的稀土尾矿进行下列表征分析:XRD显示经过400℃微波焙烧后矿物有两个Fe 2O 3特征峰消失;SEM显示矿物表面出现了一些裂缝和孔隙,且矿物表面有不同程度的坍塌;程序升温还原(H 2-TPR)显示经过400℃焙烧后矿物还原温度范围变宽,且还原峰出峰温度提前。本研究结果对白云鄂博稀土尾矿的高效综合利用具有一定的指导意义。

The characteristics of chemical composition,mineral composition and mineral embedding of rare earth tailings were studied by X-ray fluorescence spectrometer(XRF),X-ray diffractometer(XRD),scanning electron microscopy(SEM),advanced mineral identification and cha-racterization system(AMICS),thermogravimetric analyzer(TG)and mass spectrometer(MS).The results showed that the rare earth tailings have a complex mineral composition and a fine grain size.Iron mainly occured in hematite,magnetite and pyrite,and rare earth elements mainly occured in bastnasite and monazite.Rare earth tailings were calcined by five microwave calcination temperatures of 300℃,350℃,400℃,450℃and 500℃.The experimental results showed that the rare earth tailings at 400℃calcination had the highest catalytic denitrification rate.When the reaction temperature was 900℃,the denitrification rate can reach to 96.1%.Rare earth tailings of 400℃calcination were characterized as follows:XRD showed that two Fe 2O 3 characteristic peaks disappeared at 400℃calcination;SEM showed some cracks and pores on the mineral surface,and the mineral surface had different degrees of collapse;temperature programmed reduction(H 2-TPR)showed that the range of mineral reduction temperature was broadened at 400℃calcination,and the temperature of the reduction peak advanced.The results may provide the evidence for the efficient and comprehensive utilization of the rare earth tailing from Bayan Obo.