超导强磁-微波“二步法”LT细灰制备α-Fe2O3 应用基础研究

The return of pellet to the blast furnace is an effective way for the utilization of BOF LT-dust because of iron rich in it. However, with the increase of the reserves of scrap steel, the ratio of scrap in steelmaking is bound to rise and the utilization proportion of LT-dust will show a downward trend. How to develop new ideas and realize the high value-added recovery of LT-dust has become a worldwide problem faced by experts and scholars. It has not been reported about the preparation of α-Fe2O3 from LT-dust by "Two-step Method" at home and abroad, and the scientific problem is still should be explored . In this study, the idea of " Two-step Method" with strong magnetic and microwave is proposed based on our previous work. The results of the pre-research show that the extraction of iron in strong magnetic field and preparation of α-Fe2O3 by microwave is feasible. It also suggests that "magnetic flocculation suppression" is a restrictive link in the strong magnetic field and the hypothesis of "low temperature modification". This subject will study and analyze the existent morphology and dynamics character of particles in the magnetic field by multiple physicochemical methods such as Mossbauer spectrum. Interaction mechanism of influence factors such as magnetic field intensity, magnetic susceptibility, kinetic factor and particle size will also be researched. The mechanism of magnetic flocculation and its inhibitory effect will be revealed, and the mechanism of thermodynamics and kinetics of microwave modification at low temperature will be discussed to verify the hypothesis of " low temperature modification ". This study will provide a new idea for the high value-added utilization of LT-dust, provide a scientific and theoretical basis for the application of the "Two-step Method".

转炉干法灰（LT灰）富含铁资源，造球回炉是当前有效途径。然而，随着废钢储量的增加转炉废钢比将上升，原LT灰回炉比例也必将呈现下降趋势。如何开拓新的思路，实现LT灰高附加值回用成为专家学者面临的世界性难题。超导强磁-微波“二步法”LT细灰制备α-Fe2O3技术国内外未见报导，其中的科学问题尚待探寻。本项目提出超导强磁富集-微波改性“二步法”工艺设想，预研结果显示，铁元素超强磁场富集提取以及氧化铁微波改性制备α-Fe2O3可行，并提出“磁絮凝抑制”为强磁场下分离提取限制性环节及“低温改性”假说。本项目将借助穆斯堡尔谱等多种理化检测手段，解析LT细灰中颗粒物在磁场中的形态与动力学行为，研究场强、磁化率及动力学等因素的交互影响规律，揭示磁絮凝及其抑制作用机制，并探讨低温微波改性热力学及动力学影响机制，验证假说。为LT灰高附加值资源化利用提供一个全新的思路，为“二步法”的应用提供科学基础及理论依据。

转炉干法灰（LT灰）富含铁资源，如何开拓新的思路，实现LT灰高附加值回用成为专家学者面临的世界性难题。课题组基于现有试验设备搭建具有科学研究功能的成套系统，形成了完整的超导强磁富集-微波改性“二步法”关键技术及理论体系，主要研究内容：（1）解析了转炉干法灰的物相组成、赋存状态、粒度组成及特性，为探究LT细粉在超导高强磁场中的动力学行为及高效磁分离机制提供可靠的数据基础。（2）基于COMSOL Multiphysics仿真软件分析LT细灰颗粒在高梯度磁分离过程中磁性微粒的运动过程，通过分析磁场、流场状态，在考虑磁场梯度力、流体、曳力等的情况下建立了超导高梯度磁场捕集磁性微粒的动力学模型，研究了磁介质截面对粒子捕获效果（菱形>椭圆>圆），并且结合颗粒运动的动力学模型建立了磁分离过程中液固两相流动的理论模型。（3）借助SEM、XRD、TEM、粒度分析仪等手段，研究了影响颗粒物分离效果的各个因素及交互作用机制，揭示了超导强磁选体系中矿浆中磁性颗粒的非选择性团聚机制，验证了“磁絮凝抑制机制”为超导强磁场下影响铁氧化物提取的限制性环节这一假说的正确性。基于多组分散剂添加颗粒分选对比试验，优化确定了铁氧化物颗粒高效磁分离关键技术参数，揭示了磁分离体系磁絮凝抑制作用机制；（4）分析了Fe3O4在不同微波场条件下向α-Fe2O3物相转变规律，揭示了磁性物质在微波中加热机理主要为介电效应、涡流加热、磁损耗和磁滞效应，验证了“低温改性”假说的正确性，并进行微波加热改性制备α-Fe2O3的热力学及动力学机理研究，形成应用基础理论体系。该项目科学研究成果应用后将具有LT灰处理成本低、绿色无害化及高值化利用等优势，具有广阔的工业化应用前景。