稀土复合铁矿还原熔分高效分离与光电化学制氢材料制备

Bayan Obo composite iron ore in Inner Mongolia has the largest rare earth (RE) deposit in China, accounting for 30% of the proven reserves in the world and more than 80% of the total reserves in China. For highly efficient recycling and value-added utilization of the resources of RE composite iron ore (RECIO) in China, it is of great significance to develop a novel process of efficient direct-reduction-melting separation of RECIO and construct high value-added photoelectrochemical (PEC) materials. This project contains three subjects: “efficient separation of RECIO”, “regulation of REs-enriched phase compositions” and “construction of RE-modified materials for PEC hydrogen generation”. These tight-knit subjects will be carried out by the following mainline: (1) premised on the efficient separation of RECIO, we aim at grasping the technology for efficiently separating the RE composite iron and then clarifying the phase-reconstruction and element migration during the reduction smelting process; (2) to achieve controllable RE-rich slag structure, the intrinsic relationship between structural characteristics of RE slag at high and normal temperature should be explored by means of multi-scale online characterization and other techniques; (3) to obtain highly active PEC electrode, the technological process for fabricating PEC electrode with RE-enriched slag as raw material will be designed, established and optimized. The ultimate goal of this project is to employ RE-enriched slag as raw material and realize the low-cost and environmental-friendly PEC electrode for highly efficient hydrogen generation.

内蒙古包头白云鄂博稀土复合铁矿是我国最大的稀土资源，占世界已探明储量的30%、我国总储量的80%以上。针对该特色资源开发稀土复合铁矿还原熔分高效分离与光电化学材料制备增值利用新工艺，对于解决我国稀土复合铁矿资源高效回收和稀土增值利用具有重要意义。本项目从“稀土复合铁矿高效分离”、“富稀土渣矿相调控”和“稀土修饰的光电化学制氢材料设计与制备”三方面展开研究工作。以稀土复合铁矿高效分离为前提基础，掌握稀土复合铁矿高效分离工艺条件并阐明还原熔分过程矿相重构和元素迁移规律；以调控富稀土渣结构为核心，借助多尺度在线表征等研究方法，构建富稀土渣高温和常温结构特征对应关系；以获得高活性光电化学电极材料为目标，设计、建立并优化基于以富稀土渣为原料的光电电极材料制备工艺流程。最终实现以富稀土渣为原料制备低成本、高效率、绿色的光电化学制氢材料。

内蒙白云鄂博稀土复合铁矿是我国最大的稀土资源，占世界已探明储量的30%、我国总储量的80%以上。开发稀土复合铁矿还原熔分高效分离与光电化学材料制备增值利用新工艺，对于解决我国稀土复合铁矿资源高效回收和稀土增值利用具有重要意义。从稀土复合铁矿高效分离、富稀土渣矿相调控和稀土修饰的光电化学制氢材料设计与制备三方面展开研究工作。最终实现以富稀土渣为原料制备低光电化学制氢材料。.将C/O为1.0的稀土铁矿含碳球团放入马弗炉中于1400℃的条件下进行还原熔分实验12min，实现稀土渣和铁的分离。稀土元素全部进入了稀土渣中，经过冷却结晶后渣中主要存在三个物相，分别为萤石、枪晶石以及稀土相(Ca,Ce,La)5(SiO4)6F。稀土相是空间群为P 63/m的六方晶系，晶胞参数a=9.5908(3)Å, b=9.5908(3)Å, c= 7.0268(2)Å, 晶胞体积V=559.75(4)Å3。结晶过程中稀土晶体内部Ca、P元素在稀土晶体内发生向外迁移现象，最终聚集在稀土相的外部边缘形成Ca3(PO4)2。.在炉冷渣外表面层边缘存在含有Nb和Ti的新稀土相，新发现的稀土相呈不规则实心状，而不是中空的六棱柱。稀土渣中共存在两种稀土相，即(Ca,Ce,La)5(SiO4)6F和(Ca,Ce,La,Mg)3(Ti,Al,Nb)2O7。前者呈六棱柱状，后者没有固定的形态，且含有钛、铌等元素。其中六棱稀土相((Ca,Ce,La)5(SiO4)6F)主要分布在炉冷渣内部，而含钛稀土相几乎全部分布在炉冷渣外表层。采用中心空化法，初步实现稀土渣中有价元素Ti、Nb和RE的富集。.采用计时电位法在NiFe/NF上电沉积一层稀土镧和铈，探究不同电沉积电流下引入镧和铈对镍铁纳米阵列OER性能影响。结果表明，在NiFe/NF上沉积La和Ce均可有效提升其OER性能，当沉积电流为50 mA时，得到La/NiFe/NF的OER效率最高；沉积电流为25 mA时，沉积得到Ce/NiFe/NF的OER效率最高。在50 mA cm-2电流密度下，La/NiFe/NF过电位为197 mV，Tafel斜率63.3 mV/dec，Ce/NiFe/NF的过电位仅216 mV，Tafel斜率为93 mV/dec。此外，在20 mA cm-2的恒定电流密度下，两者的OER效率在10 h内未发生明显波动。