转炉钢渣原位氧化及其熟料烧成化学基础研究

Inert RO phase, solid solution of two valent metal oxide, has become a great challenge for steel slag because of its presence and low early-age strength and soundness of steel slag products resulting from RO phase. The applicant proposed a new model of reconstructing and sintering steel slag in-situ oxidation, that might be the fundamental way to improve essentially the hydraulic activity of steel slag and subsequently to achieve higher added value, by virtue of using two valent oxide to form cementitious minerals crystal by chemical reaction rather than to form oxide solid solution through similar compatible principle. To explore the rules of solid solution to crystal to glass phase equilibrium of RO slag phase selective precipitation and in-situ oxidation burning coupling process. To investiage the RO phase and its evolution in the process of reconstruction of the migration law. To rationally design of in situ oxidation reaction route and then to explore iron rich clinker burning process and further to clarify the burning chemical reaction mechanism. Studying influence rules of raw materials, oxygen pressure, temperature parameters, holding time to the iron rich clinker on mineral composition and strength and then obtaining the optimum process parameters. Project is expected that the 28d activity index of modified steel slag powder add up to 95% and above and the in the cement concrete utilization reached 40%~50%. In-situ oxidation burning model will provide with a broad perspective and a new way for improving in essence steel slag cementitious properties and lay the theoretical foundation of using steel slag as building materials.

钢渣因存在惰性RO相（二价氧化物固溶体）而导致制品早期活性低、安定性不良等问题已成为规模化、资源化和更高附加值利用的极大挑战。申请者提出了重构钢渣的“析出-氧化-烧成”新工艺，它将钢渣熔渣中二价氧化物通过化学反应形成胶凝性矿物晶体，而非通过相似相容原理形成氧化物固溶体，将成为本质提升钢渣水化活性的根本出路。探索钢渣RO相选择性析出与原位氧化烧成耦合过程的固溶相-晶相-玻璃相三相平衡规律，掌握RO相及其组分在重构过程中的演化、迁移规律；合理设计原位氧化烧成反应工艺路线，探索富铁熟料烧成过程，阐明烧成化学反应机理；研究原料配比、氧分压、温度制度等对富铁熟料矿物组成及强度的影响规律，获得优化工艺参数。项目预期可使钢渣微粉28d活性指数达95%及以上，在水泥混凝土中利用率达到40%~50%；所提原位氧化烧成思路将为钢渣胶凝性能实质提升提供一种新视角和新途径，奠定钢渣建材资源化高效利用的理论基础

钢渣是炼钢脱碳、脱氧、脱磷后固态废弃物。钢渣因含一定量胶凝性硅酸三钙（C3S）、硅酸二钙（C2S），作水泥混合材或混凝土掺合料是其资源化、规模化、高附加值利用的优先方向。但钢渣存在粉磨成本高、降低制品早期强度和后期体积稳定性等问题。截止到2019年，中国钢渣综合利用率不到30%，水泥混凝土中钢渣利用率不到15%，大部分钢渣仍然采用野外堆积方式处理，累积已超12亿吨。以中高碱度转炉钢渣为研究对象，采用“析出-氧化-烧成”原位氧化工艺重构钢渣以制备富铁熟料。通过选择性析出作用解离RO相固溶体，然后利用原位氧化作用将析出组分FeO、CaO氧化，最后与外加钙铝质组分经高温化学反应烧成胶凝性富铁硅酸盐熟料矿物。本项目研究提出了“析出-氧化-烧成”钢渣重构工艺原理，提出了基础组分重构和微量组分功能重构两步技术措施，合理设计了钢渣重构工艺技术路线；研究了基础原料及其配比、调质组分、氧化剂、温度制度等对重构钢渣中胶凝熟料矿物组成的影响规律，获得了优化工艺参数。.通过研究，重构钢渣28d抗压强度能够达到42.8MPa重构钢渣微粉28d活性指数达91%及以上，在水泥和混凝土中利用率达到30%~50%。项目阶段成果已在广西柳钢环保股份有限公司进行3次中间试验研究，获得20余吨样品，效果较好。围绕上述研究，本项目申请发明专利5件，发明学术论文期刊6篇，获教育部科技进步二等奖1项，培养研究生5人、本科生9名。.项目的研究意义在于：一是证实了量大、价廉、分布广的重构钢渣胶凝可作为有效的熟料替代材料；二是重构钢渣水化活性接近于矿渣，可缓解区域内矿渣、粉煤灰等资源供应日趋紧张形势。