钼精矿氧化共挥发提取钼铼新工艺的基础研究

Molybdenum and rhenium belong to strategic metals of China. Almost all the rhenium is present as a substitute for molybdenum in molybdenite. Due to the insufficiency of rhenium resource and poor utilization of Re-bearing molybdenum mines, China is now highly reliant on rhenium imports. In present industry, Re recovery can only reach less than 70% from molybdenite concentrates through oxidative roasting process. To solve this problem, novel method characterized as pelletizing the concentrates with additives, roasting the pellets to oxidize and co-volatize Re and Mo, cooling the vapor and separating Re into water solution is put forward. The new method is an improvement to the existing technology, but it also has several technical difficulties, which includes the maintaining of pellet intensity, the collaborating control of oxidation and volatilization, the process regulation for product purification and selective recovery of rhenium. To surmount these difficulties, research will be focused on the transformation of additives during thermal treatment, kinetics of oxidation and volatilization of Mo and Re, behaviors of impurities during roasting and leaching, selective condensation and dissolution rules of rhenium oxides. Based on that, optimization mechanisms of additives for high temperature strength of pellets and kinetic conditions of oxidization and volatilization of Mo, Re will be revealed. Influence mechanisms of main impurities on oxidation, co-volatilization and separation of Mo and Re will also be examined. With these work all done, the foundation of physical chemistry about the oxidation, co-volatilization and separation of Mo and Re will be established. Finally, a novel technical prototype of Mo, Re extraction will be formed on the basis of collaborative optimization of multiple processes of roasting, volatilizing, cooling and leaching.

钼和铼均属于国家战略金属。自然界中铼几乎全部伴生于辉钼矿中，我国铼资源并不丰富，加上国内含铼钼矿综合利用水平低，造成了铼高度依赖进口的不利局面。当前工业上普遍采用氧化焙烧法处理含铼钼精矿，铼资源回收率低于70%。为解决钼铼高效分离与回收的难题，申请人构建出精矿配加添加剂造块-团块氧化焙烧共挥发钼铼-气相冷凝和水浸分离钼铼的新流程。针对该工艺存在的球块高温强度维持、氧化挥发反应协同、产品纯度控制、铼选择性回收等技术难点，本项目重点研究添加剂高温转变行为、钼铼的氧化与挥发动力学规律、杂质的高温行为与浸取规律、铼选择性凝华与浸取等，揭示添加剂提高钼精矿团块高温强度、改善钼铼氧化共挥发动力学的作用机制，查明主要杂质对钼铼氧化、挥发及分离效果的影响机制，构建钼铼氧化共挥发与分离的物理化学基础，形成焙烧、挥发、冷凝、浸取等多过程协同优化提取钼铼的新技术原型。

针对主流的钼精矿氧化焙烧-氨浸提钼/烟尘提铼工艺存在的氧化效率低、铼挥发率低等问题，项目围绕钼精矿火法冶金过程，构建了钼铼组分在高温气-液-固多相体系中反应热力学、动力学基础，揭示了钼精矿/钼焙砂中主要组分在水蒸气、高浓度SO2、甲烷等气氛中的反应转化及迁移规律，创建了钙基/铝硅基自支撑多孔骨架负载钼铼组分氧化共分离新模式及高通量惰性载气-MoO3蒸气均相还原新体系，形成了以“造块-氧化共挥发-分凝-水浸”为主线的钼精矿提取钼铼与精加工增值新流程。项目从理论上突破了传统钼铼氧化、挥发、还原冶金过程内扩散传质对反应速率的限制，扩大了反应物粒子在多相界面吸附/碰撞的有效面积；从技术上初步实现了钼精矿高效氧化-短流程制备纯MoO3-秒级合成超细Mo2C，以及铼组分深度挥发-选择性富集-高效室温提取，其中将钼精矿彻底氧化仅需25～30 min，比传统方法效率提高了6倍；钼精矿制备高纯MoO3仅需一段高温过程，流程缩短了2/3；钼铼综合回收率分别达到90.4%、98.6%，铼回收率提高了20%以上。项目实施过程发表学术论文10篇，获授权发明专利6项，培养研究生5名，负责人2021年当选了中国工程院院士。