钒钛磁铁矿钠化冶炼过程中钒钛迁移机理和调控规律研究

Vanadium and titanium are the world recognized scarce resources and strategic materials with wide applications. The vanadium and titanium magnetite is a giant iron-polymetallic deposit associated with vanadium, titanium, etc. Therefore, the comprehensive utilization of the resource is of great significance. The vanadium and titanium recovery rates are low in the existing BF-BOF process, which resulting in serious waste and environmental problems. The physical properties of melts are very important to optimize the process and develop new metallurgical process. Slag structure is the root cause to determine the control of slag structure is the key to solve the problem for efficient optimized smelting process. In the project, sodium smelting method is used to process vanadium and titanium magnetite. The key scientific problem is to understand the phase transfer mechanism and the separation regulation rules of the valuable components in the key process. Then by building a new slag system to strengthen and control the valuable components migration, the process can realize the mineral phase reconstruction, efficient enrichment and further effective separation of the valuable components. Using the methods of the theoretical analysis and the experimental research combined, we study the phase structure changes of the valuable components in the sodium smelting process, the V/ Ti migration mechanism, the reduction kinetics rules, the phase separation regulation rules, and sodium smelting technology. The project will obtain the effective separation of V/Ti with Fe. The results will not only improve the theoretical system of the sodium smelting, but also provide basic data and theoretical foundation for solving the problem for comprehensive utilization of vanadium and titanium magnetite.

钒钛是世界公认的紧缺资源和重要战略物质，应用领域广泛。钒钛磁铁矿为铁、钒、钛等多金属共伴生矿产资源，资源开发利用意义重大。现有高炉流程钒、钛回收率低，资源环境问题突出。熔渣的物理性质对于工艺流程的优化以及冶金新工艺的开发至关重要。熔渣结构是决定熔渣物化性质的根本原因，熔渣结构的深度认知和精确调控是优化冶炼工艺的重要途径。本项目采用钠化冶炼工艺处理钒钛磁铁矿，围绕关键冶炼-分离过程中矿物有价组元相间迁移传递及分离调控的关键科学问题，通过构建新的熔渣体系，强化和调控有价组元的迁移，实现矿相重构、高效富集和有效分离。采用理论分析、实验研究相结合的方法开展钠化还元过程种有价组元相结构变化规律、钒钛组元相际迁移的动力学规律及迁移机理和钠化冶炼工艺研究。本项目的实施，实现钒钛铁的高效分离，不仅完善了钠化冶炼的理论体系，也为优化钒钛磁铁矿综合利用提供基础数据和理论支撑。

本项目通过加入熔盐调控熔渣结构进行反应传质环境优化，通过改变熔渣的聚合度以及离子分布状态增强其氧化性并降低熔渣粘度，实现较低温度下渣金有效分离和钒钛的有效富集，达到钒钛磁铁矿综合利用的目的。本文以辽西地区钒钛磁铁矿精矿为原料，开展了对碱熔盐体系中钒钛磁铁矿还原过程的的研究，取得到了以下成果：.（1）通过热力学计算得到钠化-还原-熔分的温度区间为720℃~1300℃，在该温度区间内，铁精矿可以充分地被还原成金属铁，同时，矿相中的钒可以被氧化成五价钒，以钒酸钠的形式进入渣相。由Fe-C相图可知，生成铁水的最低温度为1148℃；同时对该反应进行了高温共聚焦监测，确认铁相在1120℃具有流动性。对添加不同碱熔盐用量的渣系进行粘度测定，即通过加入熔盐调控熔渣结构降低熔渣粘度，实现较低温度下渣金有效分离。.（2）考察了钠化-还原-熔分过程的最佳工艺条件，并对还原温度、添加剂用量、还原剂用量和反应时间对铁的还原熔分和钒的钠化的影响进行系统研究。结果表明还原温度、添加剂用量的增加均有利于铁的熔分，而还原剂用量的增加先强化后抑制了铁的还原熔分。还原温度的降低、添加剂用量的增加、还原剂用量的减少、还原时间的减少有助于钒的氧化钠化行为，增大了渣相的钒含量。系统研究了还原产物渣的物相组成，并确定了添加剂用量对渣相性质的影响，结果表明：最佳条件下产生的渣相主要有CaTiO3、Na16Ti10O28、NaAlSiO4和Na1.45Al1.45Si0.55O4物相，钒主要赋存于钛酸钙和铝硅酸钠物相中。 .（3）使用红外气体分析仪对实时产生的还原性气体的浓度进行在线检测，进行钒钛磁铁矿在碱熔盐存在时的还原动力学研究。结果表明，钒钛磁铁矿在碱熔盐介质中的还原反应先是界面化学反应控速，后是扩散控速，其化学反应活化能分别为E1=-55904J/mol，E2=-78538J/mol；