水泥回转窑烧成带用轻量化方镁石-镁铝尖晶石耐火材料与水泥熟料作用机理及其挂窑皮性能研究

The main disadvantages of magnesia-spinel refractory for burning zone of cement rotary kiln are poor kiln coating adherence, high thermal conductivity coefficient and high density. Lightweighting design of the magnesia-spinel refractory helps to reduce the thermal conductivity coefficient and the density, but the kiln coating adherence needs to be improved. The kiln coating adherence depends on the formed solid and liquid phases from the reaction between refractory and cement clinker, and the penetration behavior of liquid phase in refractory. But until now, the researches on the interaction between refractory and cement clinker focus mainly on the chemical reaction, and ignore the penetration behavior of the formed liquid phase in refractory. In the research project, the pore-forming in-situ technique and other method are adopted for control the microstructures and phase compositions of the lightweighting magnesia-spinel refractories. Firstly, the effects of the content, particle size and distribution of spinel in lightweighting magnesia-spinel refractories on the compositions, amounts and distribution of the formed phases at interface of refractory and cement clinker are investigated, at the same time, the penetration behavior of liquid phase from the reaction between refractories and cement clinker in the lightweighting refractories and the microstructure of penetration layer are investigated. And then, the reaction mechanisms at interface of refractory and cement clinker and the penetration mechanisms of liquid phase in refractories will be suggested, and the penetration model of liquid phase in porous refractories will be built, which will give theoretical guidance for the development of the lightweighting refractories. On the basis, the effects of phase composition and pore characterization on the kiln coating adherence will be investigated, and the relationship between the formed solid and liquid phases, the microstructure of penetration layer, and the kiln coating adherence will be found. Lastly, the optimization technology of phase composition and microstructure of lightweighting magnesia-spinel refractory will be proposed.

水泥回转窑烧成带用方镁石-镁铝尖晶石耐火材料存在挂窑皮性差、导热系数高和密度大的问题，对其进行轻量化设计有利于降低导热系数和减小密度，但需提高挂窑皮性。挂窑皮性主要取决于耐火材料与水泥熟料的固液反应产物及液相在耐火材料中的渗透，但传统研究仅限于界面固液反应机理，对液相在耐火材料中的渗透机理尚不深入。申请项目拟采用原位分解成孔法对轻量化方镁石-镁铝尖晶石耐火材料的物相组成和孔结构进行调控，研究其骨料和基质的镁铝尖晶石含量、粒度和分布及孔结构参数对耐火材料与水泥熟料固液反应产物的组成、数量和分布及液相在多孔材料中渗透行为的影响，探明轻量化耐火材料与水泥熟料的相互作用机理，建立多孔材料的高温液相渗透模型，为耐火材料轻量化奠定理论基础；在此基础上，研究物相组成和孔结构参数对挂窑皮性的影响规律，揭示固液反应产物和液相渗透结果与挂窑皮性之间的相关性，形成轻量化方镁石-镁铝尖晶石耐火材料微结构优化技术。

水泥回转窑烧成带用方镁石-镁铝尖晶石耐火材料存在挂窑皮性差、导热系数高和密度大的问题，在保证材料抗水泥熟料侵蚀和挂窑皮性能的基础上，采用多孔骨料替换致密镁砂骨料对其进行轻量化设计是解决上述问题的重要途径。. 项目在“水泥熟料与方镁石-镁铝尖晶石反应模拟研究”、“多孔MgO-Al2O3系骨料的成孔机理研究”和“水泥熟料对轻量化耐火材料侵蚀与粘附性能研究”三部分工作基础上，研究了轻量化耐火材料与水泥熟料的作用机理和挂窑皮性能，主要结果如下：.（1）通过水泥熟料与方镁石-镁铝尖晶石反应模拟研究发现：相比方镁石，尖晶石更易与水泥熟料反应产生液相，且使渗透液相的粘度增大；当尖晶石与水泥熟料循环反应次数达到30次时，液相组分浓度较接近饱和。.（2）通过多孔MgO-Al2O3系骨料的成孔机理研究发现：研究了烧成温度、原料配比和TiO2添加量对多孔MgO-Al2O3系骨料物相组成和孔结构参数的影响规律，在基于原料颗粒堆积、原料分解、尖晶石形成和反应烧结过程分析的基础上提出了多孔MgO-Al2O3系骨料的成孔机理，并形成了多孔MgO-Al2O3系骨料微米级孔调控技术。.（3）通过水泥熟料对轻量化耐火材料侵蚀与粘附性能研究发现：骨料气孔结构、骨料尖晶石含量、骨料尖晶石粒度及基质组成与结构对轻量化方镁石-镁铝尖晶石耐火材料抗水泥熟料侵蚀性能和挂窑皮性能有重要影响；轻量化耐火材料与水泥熟料接触时，尖晶石与水泥熟料反应形成液相，适量液相形成能提高轻量化方镁石-镁铝尖晶石耐火材料的抗水泥熟料性能和挂窑皮性能，当尖晶石含量超过50wt%时，会使试样遭到严重损毁；多孔骨料与基质中尖晶石含量均为25wt%时，轻量化耐火材料具有最佳的综合性能，且孔径越小、尖晶石粒度越小越有利于提高抗水泥熟料侵蚀渗透性和挂窑皮性能；水泥熟料/耐火材料界面形成的玻璃相的量、粘度及分布是影响挂窑皮性能的关键，玻璃相形成的“玻璃栓”连接水泥熟料与耐火材料使窑皮产生粘附性能。. 基于上述研究，形成了轻量化方镁石-镁铝尖晶石耐火材料微结构优化技术。