生物质灰Si/Al活性与表面电荷特性提升水泥基充填材料性能及机理研究

According to the current problems of raw materials shortage, working transportation and physical mechanics performance instability for paste filling materials in coal mines, this project intends to utilize the Si/Al activity of biomass ash and the opposite characteristics of electric charge on its particles surface to cement particles.Biomass ash was applied to cement-based paste filling material to enhance its performance stability. The surface electrical characteristics and chemical composition changes of different residual biomass ash at different calcination temperatures were studied. The changes of the mineral composition and coordination and the activation mechanism of surface binding energy of Si / Al on biomass ash by calcining temperature was explored. The effects of biomass ash content on flow rheological properties, initial and final solidification time, compressive strength and deformation and failure characteristics after solidification of fresh filling slurry were researched. The interaction mechanism between biomass ash, water molecule, cement, fly ash and coal gangue particles was explained. By studying the composition structure of the resultant and the ion concentration of pore solution in the fixed age materials, the mechanism of chemical reaction kinetics was revealed. The static anti-segregation performance control model of biomass ash-cement paste filling material and the evaluation system of filling material stability were established. The optimum proportion of material was determined by response surface method. The research results of this project can provide important theoretical guidance and technical support for coal mine filling technology to reduce costs and increase benefits, and facilitate conversion and promotion.

针对目前煤矿膏体充填材料原料短缺、工作输送和物理力学性能表现不稳定的问题，本项目拟利用生物质灰具有Si/Al活性及其颗粒表面与水泥颗粒表面电荷电性相反特征，将生物质灰应用于水泥基膏体充填材料并增强其性能稳定性。研究不同煅烧温度下残余的各异生物质灰的表面电学特征和化学成分变化，探究煅烧温度对生物质灰矿物组成及其配位改变、Si/Al表面结合能变化的活化机理，研究生物质灰掺量对新拌充填料浆的流动流变性能、初凝终凝时间以及凝固后材料的抗压强度和变形破坏特征的影响规律，阐明生物质灰、水分子、水泥、粉煤灰和煤矸石颗粒之间的相互作用机制，通过研究固定龄期材料内生成物组成结构和孔隙溶液离子浓度揭示化学反应动力学机理，构建生物质灰-水泥基膏体充填材料静态抗离析性能控制模型，建立充填材料稳定性评价体系，利用响应面法确定材料最佳配比。本项目的研究成果可为煤矿充填技术降成本增效益、易转化促推广提供重要的理论指导。

为了解决目前煤矿充填开采原材料不足、输送及力学性能不稳定、充填成本过高等问题，本项目提出“将生物质灰替代部分胶凝材料用于充填材料制备”的技术思路。基于“结构充填开采”思想理论，本项目研发了生物质灰充填新材料，选取玉米秸秆叶茎、杨树叶、柳树叶作为生物质灰的来源，分析了在500 ℃、700 ℃、850 ℃三种煅烧温度下四种生物质灰的化学成分、矿物组成和润湿性，揭示了在不同煅烧温度下四种生物质灰在饱和Ca(OH)2溶液中的火山灰活性特征，确定了最佳的煅烧温度和具有较高火山灰活性的生物质灰种类，研究了以玉米秸秆为主的生物质灰替代水泥后的充填材料的流动性能和力学性能变化规律，研究了影响宏观性能的微观机理，得到了以玉米秸秆灰为主的生物质灰充填材料的最优配比。构建生物质灰-水泥基充填材料静态抗离析性能控制模型，建立充填材料稳定性评价体系。.研究结果表明：柳树叶和杨树叶在不同的煅烧温度下呈现较弱的火山灰活性，500℃下煅烧生成的玉米秸秆灰具有最佳的火山灰活性，且Zeta电位呈负值，有利于减少充填料浆中的絮凝；以玉米秸秆灰为主要成分的生物质灰替代水泥时，流动性增大，凝结时间减小，等质量替代20%的水泥可得到最高的单轴抗压强度9.8MPa，主要原因是生物质灰中含有较多的非定型SiO2, 能在反应后期生成硅酸盐凝胶，提高材料的强度。得到了水泥基-生物质灰充填材料的最佳配比：煤矸石950kg/m3、粉煤灰380kg/m3、水泥114kg/m3、生物质灰76kg/m3、掺合料12kg/m3，经济成本90元/m3以内。现场料浆具有很好的流动性和输送性能，应用时未发生堵管，并且凝结性能较好。.利用生物质灰制备充填新材料，一方面可以扩充煤矿充填原材料的来源途径，降低煤矿充填成本；另一方面可以将生物质灰农业固体废弃物结合煤矸石、粉煤灰等工业固体废弃物资源化利用，减少工农业固体废弃物对生态环境的污染。本项目在沿空留巷巷旁充填、“三下”压煤充填开采、煤矿采空区治理等方面具有广阔的应用前景，目前已在山西、陕西、河南、山东等多个矿井实现了推广应用，并取得了良好的实施效果。

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