高钛渣中钙钛矿物相解离机理及转化动力学研究

In the process of traditional blast furnace smelting vanadium titano-magnetite, the titanium-iron element symbiosis lead to titanium elements of iron concentrate almost entirely into blast furnace slag, and it can cause the problem of poor flowing ability and difficulties in separating the hot metal from slag. However, the present theoretical knowledge based on traditional silicate slag system cannot meet the demand of efficient smelting vanadium titano-magnetite, then further studying from the dissociation mechanism and transformation kinetics of titaniferous phase in blast furnace slag is badly needed. Based on this, the applicant proposed to doing research on kinetics behavior of perovskite crystal nucleation and growth for finding out variation and property of ore in BF, studying characterization of microstructure to clear the relationship between slag properties and the structure with different perovskite contents, seeking laws of dissociation and transformations of perovskite under the condition of modifier to clarify the relationship between the change of property of titanate slag system and microstructure, and to understand the rule of perovskite transforming into other Ti-bearing materials with low melting point and its influence on macroscopic properties. The research of this project will provide theoretical basis and technical support for highly-efficient transformation and directional adjustment of occurrence form of titanium element.

传统高炉冶炼钒钛磁铁矿过程中钛，铁元素共生导致铁精矿中的钛元素几乎全部进入高炉渣，容易引起炉渣粘稠，渣铁难分等问题，而现有传统炉渣知识理论体系无法满足低品位钒钛磁铁矿资源高效强化冶炼工艺的要求，亟需从高钛渣中含钛物相的解离机理及转化动力学方面对低品位钒钛磁铁矿进行深入研究。基于此，本项目通过高钛渣炉内下降过程钙钛矿物相的形核、长大动力学研究，以明晰钒钛磁铁矿原料在高炉内部的行为规律；通过钙钛矿高温微观结构的表征，阐明不同钙钛矿含量炉渣性质与结构的关系；通过改性剂对炉渣中钙钛矿物相解离转化的关系规律探寻以阐明钛酸盐系炉渣性质变化与结构的关系，弄清钙钛矿物相高效解离及其向其他低熔点含钛物相的转化及其对宏观性质的影响。本项目的研究将为高钛型高炉渣中钛元素赋存形态的定向调控及高效转化提供理论基础和技术支持。

攀西地区的钒钛磁铁矿资源是一种多元素共生的难冶炼低品位矿，主要含有10多种可综合利用元素及潜在价值高的稀土等元素，是中国经济可持续发展的重要战略资源。考虑到今后钒钛磁铁矿优质资源的不断开采、逐渐枯竭、矿石劣质化等因素，二氧化钛含量不断提高的钒钛磁铁矿将会成为未来高炉生产的主要可利用资源，炉渣组元相对含量的进一步变化，尤其是二氧化钛含量的持续升高，将会导致现在的硅酸盐理论知识更加无法适应未来钒钛磁铁矿高效强化冶炼的基本工艺需求。基于此，本项目通过对CaO-SiO2-MgO-Al2O3-TiO2系炉渣的高温物理化学性质及演变规律研究，揭示了温度、碱度、TiO2含量与表观粘度之间的关联；采用熔滴炉、热重分析仪，结合MLA、XRD等分析检测设备，从动力学角度考察了高炉炉料下降过程中氢气和一氧化碳对浮氏体的还原过程、竞争行为模型的构建、限速环节、以及成渣行为，含钛高熔点物相软熔过程的成渣行为规律、软化阶段物相赋存状态及构成的演变行为规律；运用Factsage7.3中Phase Diagram模块分析了CaO-SiO2-MgO-Al2O3-TiO2系炉渣熔化结晶过程及其相关影响因素，并计算了含钛炉渣表观粘度、表面张力、熔化温度等。通过改性剂与炉渣中钙钛矿物相赋存状态及解离转化规律研究，明晰B2O3能抑制钙与含钛离子的结合，B2O3添加量为2%时，高炉渣中钙钛矿赋存相从42.5%下降到32.11%，结合高温共聚焦显微镜在线观测及面扫描分析，也验证了改性剂促使含钛炉渣提前熔化，Ti元素从高熔点钛赋存相迁移到其他低熔点赋存相，明显降低含钛炉渣的表观粘度与熔化性温度，有效的改善了含钛炉渣的高温冶金性能。