Fe-Csat-N-Ti体系高熔点物相析出及其调控

Titanium-bearing materials, such as ilmenite, are often charged from the furnace top to protect the blast furnace hearth and to extend campaign life. Although this technology has been applied to a large number of blast furnaces, there has not yet formed a set of the quantitative model and the evaluation method from burden, slag, molten iron and TiCxN1-x. Here,the main aims are that inspects the effect of temperature, nitrogen partial pressure and composition of molten iron on precipitation behavior of TiCxN1-x by thermodynamics. Obtains titanium distribution ratio between slag and iron and interaction between elements in molten iron. Clears influence of nitrogen partial pressure on precipitation behavior and growth of the phases with high point. Enhances the accuracy of the quantitative relationship between titanium activity in molten iron and temperature. Dynamics study of charging titanium-bearing ores to protect the hearth is proposed. Establishs the mechanism model of the chemical reaction and diffusion during protecting the hearth. Obtains the rate controlling and link point of time. Reveals the key regular to regulate protecting the hearth. Studies the micro interface phenomenon between molten iron with titanium and carbon refractory material. Explores the wetting behavior, wetting mechanism and interface features between them. Clears interface micro behavior and explore the effective ways to promote efficiency . The results of this project can provide theoretical and technical support for the technology of the furnace protection.

采用含钛炉料护炉是延长高炉寿命的关键技术之一。尽管该技术已长期应用高炉护炉，然而尚未形成一整套从炉料—炉渣—铁水—高熔点物相的转变、分配、析出、护炉的量化模型及评价方法。本研究拟开展含钛物料护炉过程钛从炉料到TiCxN1-x系统热力学基础研究，考察温度、氮分压、成分对铁水中高熔点相TiCxN1-x析出影响规律；获得钛在渣铁中分配比及铁水中其它元素与碳的相互作用；明确氮分压对TiCxN1-x析出及长大影响，进一步提升温度与Fe-Csat-N-Ti体系中钛活度间定量关系的准确性。研究护炉过程TiCxN1-x析出-传输-沉积宏观动力学，建立TiCxN1-x护炉过程化学反应和扩散传质相关机理模型，获得速率限制性环节和转换时间点，揭示定量调控TiCxN1-x护炉的本质。研究铁水与碳质耐材间界面作用，明晰含钛物料护炉过程微观界面行为。本项目研究可为护炉技术提供理论和技术支撑。

本项目针对目前高炉冶炼过程中炉缸、炉底侵蚀严重、维护难度大、严重影响高炉寿命的难题，开展了含钛原料对炉缸、炉底区在线维护基础研究，研究内容主要包括炉缸区铁水中高熔点物相析出热力学基础研究，含钛物料护炉过程研究和含钛物料护炉过程的微观界面作用（护炉机理），借助热力学软件、高温共聚焦设备和自行研发搭建的热流调控平台等研究手段，开展了系统研究，获得重要结果如下：铁水中高熔点析出相与铁水成分密切相关，当Ti含量低于0.1wt%时Fe3C为单一析出相，当生铁中钛含量低于0.45wt%，Fe3C先于TiC析出，生铁中钛含量高于0.45wt%，TiC先于Fe3C析出；实际成分铁水中钛溶解度与温度间定量关系lg[%Ti]=-5099.88/T+2.48和lg[%Ti]=-7515.9/T+3.746（氮分压为一个大气压），该结果是在考虑铁水成分影响及一定氮分压的情况，为高炉实现在线护炉及现在的数字高炉研究提供了较准确的理论参考依据；含钛铁液护炉机理可描述为：铁水区从炉底中心开始至炉底边界层，温度逐渐缓慢降低，对应的铁水粘度增加。在边界层里，温度大幅度降低，铁水粘度快速上升。温度降低同时，边界层里Ti以TiCXN1-X的形式析出，边界层粘度进一步增大，生铁逐渐凝固，高熔点TiCXN1-X将冷却后生铁钉扎在炉缸侵蚀区，从而形成以生铁为基体，TiCXN1-X钉扎在其中的保护层。基于热流平衡原理，自建热流调控平台，为高熔点物相析出在线护炉技术的研究提供了可靠方法，也为高温条件下相关研究提供了借鉴。基于理论和实验研究，在实验室对含钛铁液护炉过程进行了模拟研究，比较出水口水温与时间的关系，模拟结果与实验结果有一定的吻合度。本研究结果为高炉炉缸区侵蚀实现加钛护炉提供理论参考及可行的自动化控制手段。