氟碳铈矿制备高品位二氧化铈的研究

发布时间：2018-06-20 23:52

  本文选题：氟碳铈矿 + 抛光粉　； 参考：《成都理工大学》2015年硕士论文

【摘要】：二氧化铈是一种应用非常广泛的稀土氧化物,尤其在化学机械抛光(CMP)领域中,具有举足轻重的作用。由于对高精度光学透镜和集成电路化学机械抛光的严格要求,越来越多的注意力集中到了高品位二氧化铈的制备上来。目前主要使用硝酸铈或氯化铈等铈盐作为铈源,通过溶胶-凝胶法、水热法或者沉淀法等化学合成方法制备二氧化铈。生产成本高、工艺复杂,并且对环境造成二次污染。如今,以氟碳铈矿为原材料制备二氧化铈已经成为一个研究热点。四川氟碳铈矿储量丰富、成分单一、矿粒粗大、易选易冶,主要成分是Ce、La、Pr、Nd等轻稀土元素,为制备二氧化铈提供了丰富的原材料来源。本论文以氟碳铈矿为原材料,通过碳酸氢钠焙烧-稀盐酸浸出工艺制备高品位二氧化铈,主要进行了以下四个部分内容的研究。首先研究了氟碳铈矿加碳酸氢钠的焙烧分解机理,在此基础上研究了焙烧条件对Ce氧化率的影响。研究表明:碳酸氢钠添加量为20%,600 oC焙烧2 h,焙烧产物中Ce的氧化率大于94.50%。其次对焙烧产物进行了水洗除氟的实验研究,研究表明:液固比为15:1,50 oC水洗1 h,焙烧产物中的NaF完全浸出到水洗液中。再次利用水浸渣进行了分离提纯制备二氧化铈的实验研究,研究结果表明:按盐酸浸取-NaOH焙烧-盐酸浸取法,分离提纯得到的二氧化铈中,二氧化铈的含量为81.17%,稀土含量为96.99%,Ce的回收率为82.89%。符合稀土抛光粉国家标准对抛光粉化学成分的要求。其中优化的盐酸浸取条件为,固液比1:5,在75 oC下2 mol?L-1 HCl浸出1 h;优化的NaOH焙烧条件为,NaOH添加量为30%,500 oC焙烧0.5 h。最后对制备的二氧化铈进行了表征并对其悬浮性进行了研究。研究结果表明:500 oC,2 h焙烧得到的二氧化铈,粒径大致分布在20~100 nm之间,平均粒径大约为40 nm左右,为纳米级。500 oC~800 oC焙烧2 h得到的二氧化铈中,二次粒子的中位径在0.24~1.56μm范围内,符合稀土抛光粉国家标准对抛光粉的粒径要求。焙烧温度越高,二氧化铈的悬浮性越差,聚丙烯酸可以很好的改善二氧化铈的悬浮性。
[Abstract]:Cerium oxide is a widely used rare earth oxide, especially in the field of chemical mechanical polishing (CMP). Due to the strict requirements for high precision optical lenses and chemical mechanical polishing of integrated circuits, more and more attention has been paid to the preparation of high grade cerium oxide. At present, cerium nitrate or cerium chloride is used as cerium source. Cerium dioxide is synthesized by sol-gel method, hydrothermal method or precipitation method. The production cost is high, the process is complex, and it causes secondary pollution to the environment. Nowadays, the preparation of cerium dioxide from fluorocarbon ore has become a research hotspot. Sichuan fluorocarbon cerium ore is rich in reserves, single in composition, coarse in grain size, easy to be selected and easy to smelt. The main composition is the light rare earth elements, such as cerium lae Prande ND and so on, which provide abundant raw materials for the preparation of cerium dioxide. In this paper, high grade cerium dioxide was prepared by sodium bicarbonate roasting and leaching with dilute hydrochloric acid using fluorocarbon-cerium ore as raw material. Firstly, the calcination mechanism of fluorocarbon and sodium bicarbonate was studied, and the effect of calcination conditions on the oxidation rate of ce was studied. The results showed that the oxidation rate of ce in the calcined product was more than 94.50 when the amount of sodium bicarbonate was 20 ~ 600oC for 2 h. Secondly, the fluoride removal from roasted products was studied by water washing. The results showed that NAF from roasted products was completely leached into the washing solution for 1 h. The ratio of liquid to solid was 15: 1 ~ 1 ~ (-1) ~ (50) 鈩，

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