风淬LF炉精炼渣的水化反应机理及性能调控机制研究

The ladle furnace refining slag (LFS) is a smelting by-product in the refining process of scrap steel or crude steel. It contains a lot of minerals such as C12A7 and C2S, which has more potential for application in building materials than other steel slag. However, the naturally cooled LFS has a dense mineral structure with few defects and inferior crystal types, which leads to low hydration activity and severely restricts the utilization of LFS used in building materials. Therefore, to improve the mineral structure of LFS is the key to improve its hydration activity. In this project, the mineral structure of LFS is optimized by air-quenching method, resulting in a significant improvement in its hydration activity. Further, the hydration reaction mechanism and the regulation and optimization of hydration property for the air-quenched LFS will be studied emphatically by a variety of modern analytical testing techniques. The leaching characteristics, hydration rate, hydration degree and the microstructure of LFS will be systematically studied to reveal the hydration mechanism and microstructure evolution mechanism of LFS in hydration process, and the hydration kinetics model and the relationship between and microstructure and macroscopic properties will be also established. Further, the regulatory and optimization mechanism of hydration property will be explored. This study will provide theoretical basis and scientific guidance for the activation modification of LFS and its efficient utilization in building materials.

钢包炉(LF炉)精炼渣是废钢或粗钢精炼过程中产生的冶炼副产品，其含有大量C12A7和C2S等矿物，比其它钢渣在建材中的应用潜力要更大。但自然冷却的LF炉精炼渣的矿相结构致密、缺陷少、晶型劣，导致其水化活性低，严重制约了其建材资源化利用。因而，改善LF炉精炼渣的矿相结构是提高其水化活性的关键。为此，项目提出采用风淬急冷方法来优化LF炉精炼渣的矿相结构，以使其胶凝活性显著提高，并重点针对风淬LF炉精炼渣的水化反应机理不明确，水化性能的进一步调控机制尚未建立等问题开展深入研究，运用多种现代分析测试技术，系统研究风淬LF炉精炼渣的溶出特征、水化速率、水化程度和产物微结构等性能，来揭示风淬LF炉精炼渣的水化机理和微结构演变机制，建立其水化动力学模型及微结构与宏观性能发展的内在关系，并进一步探究其水化过程的调控机制及硬化性能的优化机理，为LF炉精炼渣的活化改性及建材资源化利用提供理论依据和科学指导。

LF炉精炼渣富含C12A7和C2S等铝硅酸盐矿物而具有较高的潜在胶凝活性，但自然冷却的LF炉精炼渣的矿相结构致密、晶型劣，导致其水化活性低、性能差，严重制约了其建材资源化利用。为此，项目提出采用风淬急冷方法来优化LF炉精炼渣的矿相结构，并针对风淬LF炉精炼渣的水化反应机理不明确，水化性能的调控方法尚未建立等问题开展深入研究。按照项目的研究方案与计划，开展的主要研究内容包括：运用XRD、BSE-EDX、NMR、SEM-EDX等现代分析测试技术，从矿相种类、晶型、形貌与微区组成、配位结构等方面分析风淬处理的LF炉精炼渣的矿相转变规律；从水化过程、水化产物、微观结构、力学性能等方面研究风淬LF炉精炼渣的水化硬化性能；从有机调控/无机优化两方面探究风淬LF炉精炼渣的水化调控与性能优化；对比研究了风淬前后LF炉精炼渣作为辅助胶凝材料对硅酸盐水泥性能的影响规律。主要研究结果显示：风淬LF 炉精炼渣的矿物相以非晶态C12A7和β-C2S为主，其f-MgO尺寸降低一个数量级，非常有利于水化活性与体积稳定性的提升；风淬LF 炉精炼渣的水化速率很快，凝结时间很短，早期强度发展很快(1h 强度达 8.3MPa)，但中后期性能发展缓慢。有机调凝剂可有效延缓 风淬精炼渣的早期水化硬化过程，二水/半水石膏可优化其水化产物组成、形貌与结构，也可适量延缓其早期水化速率，从而显著提高风淬 LF 炉精炼渣的早后期性能。在此基础上，构建了风淬精炼渣-调凝剂-石膏的三元复合胶凝材料体系，其具有优异的水化硬化性能。此外，风淬后的精炼渣相比于自然冷却精炼渣，其作为辅助胶凝材料有明显促进硅酸盐水泥速凝早强的作用。项目成果有望为LF炉精炼渣的建材资源化高效利用提供理论依据和技术支撑。项目完成了预期的成果指标，发表SCI期刊学术论文9篇，授权国家发明专利5项，获得相关奖励/荣誉2项，培养硕士研究生3名，指导博士后1名等。