高Al2O3高炉渣系组元活度的研究

In recent years, Al2O3 content in the blast furnace slag increases significantly, which causes the desulphurization capacity decreasing, with the increase of Al2O3 content in iron ore. Sulfur (S) element is mainly removed by interfacial chemical reaction in blast furnace smelting. The activities of components involved in the desulphurization reaction are important factors affecting the efficiency of desulfurization. The activities of slag components have been one of the core problems in metallurgical thermodynamics. So, it is significance to discuss the effects of activities on desulfurization. In this study, it focus on four of key science problems: 1) analyzing reaction mechanism among components at elevated temperatures and understanding mineral structure of CaO-SiO2-MgO-15%~20%Al2O3 slag; 2) establishing an activity prediction model based on a revised molecular-ion coexistence theory and phase diagram analysis; 3) measuring activities, designing the experiment for measuring activities, and revising the proposed prediction model by using revising index according to the experimental result; 4) discussing desulfurization mechanism based on thermodynamics, prediction model, and experimental analyses. This study is conducted by combining the knowledge of physical-chemistry, transport phenomena, metallurgical reaction engineering, metallurgy, mineragraphy, and material science with modern related analyses methods and detection technologies in order to establish an accurate prediction model of activity, resolve desulfurization mechanism, optimize the design of blast furnace slag, and build solid science foundation for reasonable iron-making process with blast furnace.

随着高Al2O3铁矿石使用量的增加，高炉炉渣的Al2O3含量大幅度攀升，使得炉渣的脱硫能力下降。高炉冶炼过程中，炉料中的硫（S）元素主要是通过界面化学反应脱除的，参与脱硫反应的各组元的活度直接影响脱硫效果，因此探讨各组元活度对炉渣脱硫能力的影响具有重要的学术研究意义和实际应用价值。本项目拟基于修正的分子离子共存理论，围绕高Al2O3（15~20%）高炉渣系（CaO-SiO2-MgO-Al2O3四元系）的炉渣矿物组成、活度预测模型、组元活度测定与预测模型的修正、脱硫理论与实践等关键科学问题开展研究，立足于解析各组元相互协同作用机制，运用火法冶金研究方法，理论分析结合现代检测分析方法，探讨炉渣各组元之间相互协同作用的影响，解析脱硫本质，建立具有普适性的高精度活度预测模型、完善高炉炉渣活度数据库、优化高炉渣系，为制定科学合理的高炉炼铁工艺奠定扎实的科学基础。

近年来随着高炉原料中进口高Al2O3矿石用量的增加，导致炉渣中Al2O3含量相应增加，炉渣冶金性能（如：脱硫能力，炉渣流动性）下降，造成高炉生产不稳定。目前针对高MgO、Al2O3炉渣脱硫能力的研究，缺乏系统合理的考量，故有必要从理论上深入探讨MgO、Al2O3对炉渣脱硫能力的影响。高炉冶炼过程脱硫主要是通过渣—金界面化学反应进行，参与脱硫反应的各组元的活度是影响脱硫过程的重要因素，但从组元活度角度探讨MgO、Al2O3对炉渣脱硫能力影响的研究鲜有报道。基于此背景，本研究针对高Al2O3高炉渣系，建立了基于分子–离子共存理论的组元活度预测模型和脱硫能力预测模型，确定组元活度和脱硫能力，深入探讨炉渣微观结构与组元活度、脱硫能力之间的内在机制，解析脱硫本质，相关研究结果不仅填补了相关学术研究空白，具有重要的学术研究意义，而且具有重要的实践指导意义，有助于优化高炉渣系、改善冶金性能、带来丰厚的经济和社会效益。其重要成果如下：.（1）建立了基于分子–离子共存理论的组元活度预测模型，比对理论模型数据与试验结果，引入了修正因子修正预测模型，有效地提高了预测模型的精度与适用范围。.（2）确定了不同温度（1723–1823K）、不同成分条件下高Al2O3高炉渣系组元活度，解析了炉渣微观结构和组元活度之间的内在机制、各个组元之间的协同作用机制，填补了相关领域的学术空白，完善了高炉炉渣活度热力学数据库。.（3）建立了基于分子–离子共存理论的脱硫能力预测模型，比对理论模型数据与试验结果，引入了修正因子修正预测模型，有效地提高了预测模型的精度与适用范围。.（4）确定了不同温度（1723–1823K）、不同成分条件下高Al2O3高炉渣系脱硫能力，解析了炉渣微观结构和脱硫能力之间的内在机制，填补了相关领域的学术空白，完善了高炉炉渣脱硫能力热力学数据库。.（5）建立起组元活度与炉渣脱硫效果的关系，解析脱硫本质，具有重要的学术研究价值，为优化渣系、制定科学合理的高炉炼铁工艺奠定扎实的科学基础。