铁酸锌选择性还原铁锌物相定向调控机理研究

The high-efficient clean treatment of zinc ferrite is a urgent problem confronted by zinc smelting industry of China. As large amounts of iron residues could be generated in the the industrial treatment processes of zinc ferrite, a huge number of iron was wasted and become secondary heavy metal contamination. The reduction roasting of zinc ferrite, in which process the iron phase in roasting product could be modifided to form magnetite by changing roasting conditions, is a novel promising idea for the clean treatment of zinc ferrite because that iron could be separated in the further magnetic dressing process and secondary contamination could be mitigated. It was observed by our preliminary research that zinc ferrite could be selectively decomposed into magnetite and zinc oxide by the gas mixture of CO and CO2, however, the generation of zinc iron solid solution shoud be avoided as it could reduce the decomposition rate of zinc ferrite. To achieve this, the following aspects will be studied: 1) phase diagram of zinc ferrite in reduction roasting；2）the reduction kinetics of zinc ferrite; 3) microstructure change and ion migration of zinc ferrite during redution roasting; 4) interaction of phases in complicated zinc ferrite system. All the studies are dedicated for the decomposition kinetics of zinc ferrite; revealing the mechanism of the decomposition of zinc ferrite, the recrystallization of zinc oxide and the formation of zinc iron solid solution; expounding the decomposition of zinc ferrite in zinc or iron rich system to realize the selective decomposition of zinc ferrite into Fe3O4 and ZnO as well as construct a technology prototype of high-efficient clean treatment of zinc ferrite.

铁酸锌的高效清洁处理是我国锌冶炼行业亟待解决的重大难题。现行的铁酸锌处理工艺虽锌回收效率高，但易导致大量难处理铁渣形成，造成铁资源的严重浪费和二次污染。在铁酸锌还原分解过程调控铁的物相，通过后续磁选分离高效回收铁资源是避免铁渣二次污染的一种全新技术思路。前期研究发现CO/CO2可选择性分解铁酸锌生成Fe3O4，但锌铁固溶体的生成导致铁酸锌分解率较低。解决问题关键瓶颈在于还原过程中锌铁固溶体的调控。针对该难题拟研究：1）构建铁酸锌体系还原基础相图；2）铁酸锌选择性还原动力学特性研究；3）铁酸锌显微组织物相转变及离子迁移规律研究；4）复杂铁酸锌选择性还原过程物相间相互作用研究。旨在阐明铁酸锌解离、铁锌固溶体形成与分离的机制，揭示非化学计量比铁酸锌分解及包裹效应作用机制，实现铁酸锌高效选择性还原分解，形成含铁酸锌物料高效清洁处理技术原型。

铁酸锌的高效清洁处理是我国锌冶炼行业亟待解决的重大难题。现行的铁酸锌处理工艺虽锌回收效率高，但易导致大量难处理铁渣形成，造成铁资源的严重浪费和二次污染。在铁酸锌还原分解过程调控铁的物相，通过后续磁选分离高效冋收铁资源是避免铁渣二次污染的一种全新技术思路。硏究发现CO、SO2等还原气氛可实现选择性分解铁酸锌生成Fe304，但锌铁固溶体的生成导致铁酸锌分解率较低。解决问题关键瓶颈在于抑制还原过程中锌铁固溶体的形成。.通过四年研究，项目取得了四方面的进展与成果：（1）构建了Fe-Zn-O体系平衡相图，解析了铁酸锌CO还原过程热力学变化规律，构建CO及C还原铁酸锌的优势区域，通过热重分析证实了CO/CO2复合气氛选择性分解铁酸锌的热力学可行性；（2）证实了CO/CO2气氛中CO2可修复反应物表面氧空位，抑制固溶体Fe0.85-xZnxO的形成，避免产物Fe3O4的深度还原，证实了铁酸锌还原过程Zn、O原子的迁移机制与氧化锌的异位形核-核生长机制，揭示了CO还原铁酸锌四阶段特征，构建了CO还原铁酸锌的动力学方程；（3）优化了锌焙砂还原工艺，获取了最佳工艺参数，实现Zn回收超过90%，有效抑制了铁锌固溶体形成；(4)率先发现并证实了SO2具有选择性分解铁酸锌，抑制了铁锌固溶体形成的能力，可实现Zn回收率达92%以上；系统研究了SO2还原分解铁酸锌热力学特征，构建还原优势区域；揭示了铁酸锌分解历程可分为8个阶段，遵循收缩核模型，建立了等温动力学模型。.基于本项目成果开发了含铁酸锌、铁橄榄石等难处理资源选择“还原分解-磁化分离回收”的清洁化处理新工艺，实现了铁、铜、锌等有价资源的高效回收。项目成果应用于郴州丰越环保股份有限公司，建立了5000t/a锌焙砂处理示范工程。.本项目共发表SCI论文9篇，会议论文1篇，作国际学术会议邀请报告2次，已授权发明专利89项，荣获2017年湖南省首届创新奖1项。获优青资助；获国家创新人才推进计划中青年科技领军人才，湖南科技领军人才等荣誉。