钒钛磁铁矿球团还原膨胀的结晶化学变化机制

Pellet is the main furnace burden in both blast furnace and non-blast furnace methods in the utilization of vanadium-titanium magnet concentrates. However, the reduction expansion of vanadium-titanium magnetite pellets is serious, which is one of the bottlenecks to improve blast furnace smelting efficiency and realize the industrial application of the non-blast furnace methods. There are multi minerals in the vanadium-titanium magnetite pellets, causing complex mechanism of crystallochemical change, which is hard to be precisely researched by traditional detection means. Synchrotron radiation technology will be used to precisely and systemically investigate the lattice transition during the phase’s transformation of Panxi vanadium-titanium magnetite pellets’ reduction, combined with the thermodynamics, mineralogy and solid physics. The relationship between lattice transition and pellet volume change will be established, and the mechanism of crystallochemical change during reduction will be revealed, which provides theoretical support for the development of active control methods. The finish of this project will not only improve the blast furnace smelting efficiency, but also promote the industrialization of non-blast furnace methods, which could realize the clean and efficient utilization of vanadium-titanium magnetite resources. Moreover, the research of this project is of great guiding significance for the research on the reduction expansion mechanism of other complex iron ore pellets.

钒钛磁铁矿球团是高炉法和非高炉法的主要炉料，但其还原过程膨胀现象严重。该问题限制了高炉法冶炼效率的提高，并阻碍了非高炉法综合利用钒钛磁铁矿的工业化应用。本项目以攀西钒钛磁铁矿球团为研究对象，针对钒钛磁铁矿球团多矿相，结晶化学变化机制复杂，常规研究手段难以精确揭示其还原膨胀微观机理的难题，采用同步辐射XRD，结合热力学、矿物学和固体物理等理论基础，精确研究球团还原矿相演变过程中晶格变化规律，建立晶格转变与球团体积变化的关系，揭示钒钛磁铁矿球团还原膨胀结晶化学变化机制，为开发其还原膨胀主动控制方法提供理论支撑。本项目的完成将提高我国钒钛磁铁矿高炉冶炼效率，推动我国钒钛磁铁矿非高炉法工业化，实现我国钒钛磁铁矿资源高效利用。同时对其他铁矿球团的还原膨胀机理研究也具有重要的指导意义。

钒钛磁铁矿球团的还原膨胀现象严重，造成其冶炼过程难以顺行。该问题限制了高炉法冶炼效率的提高，并阻碍了非高炉法的工业化应用。本项目从晶格转变角度，深入研究了钒钛磁铁矿球团氧化固结和还原过程的矿相演变和晶格变化规律，揭示了钒钛磁铁矿球团还原膨胀结晶化学变化机制；提出有效的钒钛磁铁矿球团还原膨胀主动控制方法，制备出低还原膨胀率的钒钛磁铁矿球团。.钒钛磁铁矿球团还原膨胀的主要晶格转变，是三方晶系的钛赤铁矿（晶胞体积100.79Å3）还原成立方晶系钛磁铁矿（晶胞体积575.94Å3），造成球团体积大量膨胀。同时，斜方晶系的高铁板钛矿（晶胞体积362.12Å3）还原成立方晶系钛铁晶石（晶胞体积614.13Å3），其晶格转变也导致钒钛磁铁矿球团还原体积膨胀。两者晶型转变造成钒钛磁铁矿球团还原膨胀现象严重，强度显著降低，产生大量粉末。.强化钒钛磁铁矿球团固结，钙质和镁质添加剂，提高还原气体中H2的比例，提高还原温度，能有效抑制钒钛磁铁矿球团还原膨胀问题。钒钛磁铁矿氧化球团抗压强度由2200 N/P提高至2600 N/P，其RDI+6.3mm由43.28%提高至87.24%。碱度由自然碱度0.32提升至0.8时，RDI+6.3mm由87.24%提高至94.38%；外配1%的氧化镁，RDI+6.3mm由87.24%提升至94.70%。H2和CO单一气体还原时，钒钛磁铁矿球团还原膨胀和粉化现象不明显；当H2/(H2+CO)从0增加到0.17时，其RDI+6.3mm由96.99%骤降至0%。随着H2含量进一步增加，其还原膨胀性能改善。还原温度从450℃提升至500℃时，钒钛磁铁矿球团发生严重的粉化问题；随着还原温度升高，还原膨胀和粉化现象好转，700℃后粉末量大幅减少。.本项目的完成为制备低还原膨胀率的钒钛磁铁矿球团提供了理论基础和应用方法，有利于提高我国钒钛磁铁矿高炉冶炼效率，推动我国钒钛磁铁矿非高炉法工业化，实现我国钒钛磁铁矿资源高效利用。同时对其他铁矿球团的还原膨胀机理研究也具有重要的指导意义。