【作者】 徐永亮；

【导师】 王德明；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2011， 博士

【摘要】 在我国西部和北部地区,煤炭资源丰富但矿井火灾严重,由于缺土少水,常规注浆使用成本偏高,但山砂和粉煤灰资源丰富。为了提高注砂质量,减少注砂时水的消耗量,提高防灭火效率,本文开展了防治煤自燃的悬砂胶体研究。研制出了防治煤自燃的由无机凝胶材料和有机高聚物组成的悬砂胶体复合添加材料。本文测试分析了黄土、粉煤灰和山砂等颗粒状注浆固相材料在颗粒粒径、物相组成以及显微结构等方面的共性;研制了悬砂胶体复合添加材料:该材料悬砂效果显著,常温常压下少量添加即可与砂按比例快速制备出均匀稳定的悬稠砂浆,操作过程简便快捷,克服了悬砂稠化剂制备过程繁琐且需高温加热的不足;通过流变实验研究了浓度、剪切速率和温度对悬砂胶体粘度的影响,建立了悬砂胶体流变本构方程。建立了颗粒双电层空间作用模型,揭示了山砂颗粒在悬砂胶体中的悬浮机理。悬砂胶体随添加浓度增加表面张力也随之增加,表明胶体体系有向不稳定方向发展的倾向;山砂颗粒在悬砂胶体中的稳定悬浮,不仅受到胶体中高聚物主链通过羧基与钙离子作用在山砂表面形成的立体分布结构的影响,还存在颗粒双电层的空间作用效应:悬砂胶体体系的稳定得益于体系中胶体粒子荷负电形成的双电层结构;山砂中电离产生的钙离子吸附在砂粒外层形成表面荷正电的固体颗粒双电层;而砂粒表面立体分布结构还对砂粒间的聚集产生空间位阻效应以阻碍山砂颗粒之间的空间团聚;因此,根据颗粒双电层空间作用模型,悬砂胶体粒子对于山砂的分散作用表现在颗粒双电层影响下造成的静电力效应及山砂粒子间的空间位阻效应两者的协同作用,即能保证胶体自身体系的稳定性,更为重要的是保证了山砂颗粒能稳定地悬浮于悬砂胶体体系中。力学分析表明只有当山砂颗粒对其下部流体的应力小于胶体本身的屈服应力时,才可使山砂颗粒稳定悬浮。基于结构两相流理论构建了悬稠砂浆两相流体管路流动数学模型。实验研究了剪切速率、含砂量和温度对悬稠砂浆流变性的影响,推导了悬稠砂浆流变本构方程;基于结构两相流理论,综合考虑液相粘度、固相颗粒相间碰撞和颗粒脉动影响等因素建立了悬稠砂浆管路流动数学模型;并利用流体模拟软件对管路中砂浆流速、粘度和阻力损失等流动参数进行了模拟解算;通过砂浆制备与管路流动模拟系统对管路中砂浆流量和阻力损失参数进行了测试;对比分析试验测试数据和数值模拟结果二者具有较好的吻合性,验证了数学模型建立的可靠性。研究并阐述了悬砂胶体降低煤中活性基团反应活性的阻化机理。利用红外光谱实验、程序升温实验和指标气体测试,从本质和现象上对悬砂胶体抑制煤自燃性能进行了综合考察和分析,研究并阐述了悬砂胶体对煤自燃过程的阻化机理:在煤氧化升温过程中,悬砂胶体能够有效降低脂肪族甲基、亚甲基、醇酚类羟基、羰基、稠环中C=C和芳烃-CH基团等活性基团的反应活性,增加氧化反应能垒,抑制官能团参与氧化反应的能力,增加煤氧化反应活化能,从而减少反应过程中CO和C2H4气体的生成,降低煤自燃过程的氧化反应速率,抑制煤自燃过程;并通过封堵压力测试考察了悬砂胶体的封堵漏风隔氧能力;实验结果体现了悬砂胶体对煤氧化升温过程具有显著的阻化性能。本文通过实验分析和理论研究,对悬砂胶体流变性、悬浮性、流动性及其对煤自燃过程的阻化性能等进行了系统的研究和分析,对悬砂防灭火技术进行了精简和优化,解决了悬砂胶体对山砂固相颗粒的悬浮机理、悬稠砂浆管路流动阻力特性到及胶体本身对煤氧化升温过程的阻化机理等方面的难题,为以后该防灭火材料的大力推广奠定了理论基础。该论文有图83幅,表8个,参考文献140篇。更多还原

【Abstract】 Grouting is one of the methods which were widely applied in fire control technology in coal mine at present. In fact, Northwest China has abundant coal resource but with serious mine fire disaster and shortage of water and loess, the cost of conventional grouting is high. However, in those areas there are abundant sand and fly ash resources, in order to improve the quality of sand injection and reduce the wastage of water when grouting, the paper make a further study on the new sand-suspended colloid materials of fire control technology.The new compound material of sand-suspended colloid was developed, which was composed of mineral inorganic gel and organic polymer. In the paper, the general characters of loess, fly ash and mountain with granular shape, such as the grain diameter, phase composition, microstructure observation, were analyzed firstly. Then through enough experiments and improvement of original additives, the sand-suspended colloid materials was developed, and by little addition of it, the steady sand-suspended slurry can be produced easily. By the further study on impact factors with different concentrations, shear rate and temperatures to sand-suspended colloid viscosity, we generated the rheology constitutive equation of sand-suspended colloid.In order to study the suspended mechanisms of solid particles in sand-suspended colloid, the space work model based on theory of double-electric layer is established. The surface tension of sand-suspended was increasing with the concentration of additives, which illustrate that the colloid system has a tendency for unsteady status. Double electric layer that formed by colloid particles charged plays the important role about the stability in sand-suspended colloid system, the dispersion of sand-suspended colloid to sand-suspended slurry is the synergistic effect combined with steric effect and electrostatic repulsion effect that created by the reason of double electric layer particles. So that it can ensure the stability of colloid system and sand-suspended slurry. The mechanical analysis indicated that under the conditions of stress of rock sand particles to the lower part of fluid less than yield stress of colloid itself, the sand can suspend steadily.A mathematical model of two-phase flow in pipeline for sand-suspended colloid based on two-phase flow theory is established. The experimental study on impact factors of sand-suspended slurry rheology, for example, the shear rate, suspended sediment concentration and temperature, was carried out; meanwhile the rheology constitutive equation of sand-suspended slurry was presented. The yield pseudo plastic two-phase fluid of sand-suspended slurry flow model in the pipeline was established, and the solution of the model was also presented. By using the sand-suspended slurry preparation and flow pipeline system, the flow parameters of it were tested. The results show that the numerical and test results have good agreement. Thus it verifies the reliability of the mathematical model.The inhibition mechanism of sand-suspended colloid is investigated, which could depress the reactivity of active groups in coal. It was studied that the sand-suspended colloidal has an influence on the structure of functional groups, cross point temperature, index gas and the apparent activation energy in the temperature oxidation process of different kinds of coal. Through in-situ Fourier infrared spectrum experiment, it was showed that the sand-suspended colloid can inhibit the activity and generation of methyl, methylene, hydroxyl, carboxyl, carbonyl and functional groups of aliphatic. The resistance performance experiment, based on programmed temperature method, was also showed that the sand-suspended colloid has an important influence on the cross point temperature, index gas and the apparent activation energy of lignite, kennel coal, gas-fat coal and lean coal in oxidation heating process. So it has a hysteresis effect on the coal oxidation process. Based on the theoretical research of sand-suspended colloid, sealing pressure testing and stored coal fire, the ability of sealing and fire control was inspected.Based on the experiment and theoretical research, the paper analyzed the rheology, suspension property, liquidity and fire control ability of sand-suspended colloid, optimized the sand-suspended fire control technology, and made clear the problems of the sand-suspended colloid suspend mechanism, flowed friction property and ignition inhibition mechanism, which laid the theoretical foundation for the application of this technology.更多还原