高铝粉煤灰协同活化制备莫来石工艺基础研究

发布时间：2018-01-17 13:27

本文关键词：高铝粉煤灰协同活化制备莫来石工艺基础研究　出处：《中国科学院大学(中国科学院过程工程研究所)》2017年博士论文　论文类型：学位论文

【摘要】：高铝粉煤灰产生于我国内蒙古中西部、山西北部和宁夏东部地区,年排放量达3000万吨,其中Al_2O_3和SiO_2含量分别高达40%和35%以上,主要以莫来石-刚玉相和非晶相形式存在。针对其资源特点,制备以莫来石为代表的铝硅系耐火材料已成为高铝粉煤灰资源化利用的重要途径。本文针对粉煤灰原料铝硅比低、杂质含量高的问题,提出了机械-化学协同活-化深度脱硅除杂制备莫来石新工艺,重点开展了非晶相SiO_2多场温和活化、酸活化过程硅溶胶凝胶化调控、晶相/非晶相高效剥离机理、深度脱硅动力学等研究;进一步开展了耦合调控活化酸液制备聚合氯化铝、脱硅粉煤灰物性调控制备莫来石、物质流分析与全流程工艺优化等研究,形成了高铝粉煤灰协同活化-深度脱硅制备莫来石耐火材料多联产技术体系。主要研究内容和结论如下:(1)开展了机械、化学、微波单独和协同活化方式对非晶态SiO_2反应活性的影响规律研究,提出"活化指数"用于评价其反应活性,确定了机械-化学活化为最优活化方式,并完成工艺优化,活化指数可达12.4%,较粉煤灰原料反应活性提高8倍,同时Ca、Fe、Mg等杂质含量均可降低至1%以下。进一步开展了协同活化机理研究,采用电子探针、核磁等分析发现协同活化过程可有效降低其晶相/非晶相嵌粘夹裹程度,促进惰性玻璃相Q4(3A1)结构转化为活性较高的Q4(2A1)和Q2(1A1),增加Si-O-活性作用位点,实现杂质的深度脱除和非晶态SiO_2反应活性的大幅提高。(2)基于DLVO理论和Zeta电位理论,建立了电位、粘度及pH实时监测一体化平台,结合TEM及in-situ FTIRS分析突变过程胶体粒子形貌及Si-O-Si配位变化,进一步考察了不同价态阳离子(K+、Na+、Ca2+、Mg2+、Fe3+、Al3+)和阴离子(Cl-、Br-、I-、NO3-、SO42-、PO43-)对硅溶胶凝胶化过程的影响,研究发现离子价态和浓度过高极易破坏双电层结构,促进凝胶化过程。因此,选择盐酸作为活化酸液,通过控制体系pH小于1.9,并调控溶液中阳离子含量,可有效缓解凝胶转化过程,提高液固分离效率。(3)针对脱硅正交实验结果,考察了不同因素对脱硅率及矿相变化的影响,在优工艺条件下,脱硅率可达60%,铝硅比可达2.8,钠含量可控制在0.5%以下;进一步开展了非晶相复杂配位Al-O-Si变化规律、元素赋存状态及转化规律、颗粒孔道结构、矿相及形貌变化规律等研究,发现脱硅反应主要是碱介质强化进攻非晶态SiO_2,同时高效破坏非晶相中Al-O-Si配位结构,实现非晶态SiO_2的高效剥离;基于脱硅工艺及机理分析,开展了脱硅动力学研究,明确了脱硅反应前期受表面反应控制,反应后期受固膜扩散控制,实现了非晶态SiO_2高效脱除同时避免副反应发生,为脱硅过程的有效控制、工程设计与放大提供基础数据。(4)开发了耦合调控制备聚合氯化铝关键技术,考察了不同因素对聚合氯化铝制备过程的影响,在优化条件下,钙离子的架桥作用促进铝离子高效聚合,得到聚合氯化铝产品中Al_2O_3含量高达11%,盐基度为76%,密度为1.1g/mL,其性能指标均满足国标要求。开发了脱硅粉煤灰物性调控制备莫来石关键技术,考察了不同因素对莫来石关键指标体积密度和显气孔率的影响,在优化条件下,莫来石晶粒生长为棒状莫来石,得到的莫来石产品氧化铝含量高于70%,体积密度高于2.85g/cm3,显气孔率小于0.5%,其性能指标均满足国标要求。在此基础上进行了整体工艺物料衡算、物质流分析和初步经济性评价,为工程放大提供关键基础数据。
[Abstract]:High alumina fly ash produced in China's central and Western Inner Mongolia, northern Shanxi and Eastern Ningxia, annual emissions of 30 million tons, of which Al_2O_3 and SiO_2 were higher than 40% and 35%, mainly in the mullite corundum phase and non crystal phase form. According to the characteristics of resources, alumina silica material prepared by Mo as the representative of the mullite has become an important way of high alumina fly ash resource utilization. Based on the fly ash aluminum silicon ratio is low, high impurity content, the chemical mechanical synergetic live - deep desilication purification preparation of mullite new technology, focusing on the amorphous SiO_2 a mild activation the activation process of silica sol gel, acid regulation, crystalline / amorphous phase, stripping mechanism research of deep desilication kinetics; further the coupling activation acid preparation of polyaluminium chloride, desiliconized fly ash physical control preparation of mullite, Study on the whole process analysis and process optimization of material flow, the formation of high alumina fly ash CO activation of deep desilication preparation of mullite refractories polygeneration technology system. The main research contents and conclusions are as follows: (1) the mechanical, chemical, and synergistic effects of microwave single activation method on amorphous SiO_2 reaction activity law the research, put forward "activation index is used to evaluate the reactivity, determine the chemical mechanical activation for optimal activation, and complete the process optimization, the activation index was 12.4%, compared with the reaction of fly ash was increased 8 times, while Ca, Fe, Mg and other impurities can be reduced to below 1%. The further development of the mechanism research cooperative activation, using electron probe, NMR analysis showed that cooperative activation process can effectively reduce the crystalline / amorphous phase embedded clips, promote the inert glass phase Q4 (3A1) structure into high activity of Q4 (2A1) And Q2 (1A1), increased Si-O- activity site, deep removal and amorphous SiO_2 reaction activity of impurities increased markedly. (2) the DLVO theory and the Zeta potential was established based on the theory of potential, viscosity and pH real-time monitoring integration platform, combined with TEM and in-situ analysis of the FTIRS mutation process of colloidal particle morphology and Si-O-Si coordination changes, further study of different valence cations (K+, Na+, Ca2+, Mg2+, Fe3+, Al3+) and anion (Cl-, Br-, I-, NO3-, SO42-, PO43-) influence on the sol gel process, the study found that the valence and concentration of ions is too high can easily damage the electric double layer structure to promote the gelation process. Therefore, choose hydrochloric acid as acid activation, through the control system of pH is less than 1.9, and the regulation of cation content in solution, which can effectively alleviate the gel transformation process, improve the separation efficiency of the solid liquid. (3) for the desilication of the result of the orthogonal experiment, the effects of different factors on the removal of Effect of silicon ratio and mineral phase change, in excellent condition, the desilication rate is 60%, ratio up to 2.8 silicon aluminum, sodium content can be controlled below 0.5%; the further development of the amorphous phase coordination complex Al-O-Si changes, elements of occurrence and transformation rules, particle pore structure, mineral phase and morphology study changes, found that desilication reaction is mainly alkali medium enhanced amorphous SiO_2 attack, at the same time, destruction of the amorphous phase Al-O-Si coordination structure, to achieve efficient stripping of amorphous SiO_2; analyzed the process and mechanism of silicon based on the developed desilicon dynamics research, the pre desilication reaction controlled by surface reaction. The reaction of late by solid membrane diffusion, the amorphous SiO_2 removal efficiency and avoid the occurrence of side reactions, in order to effectively control the desilication process, engineering design and amplification to provide basic data. (4) developed coupling preparation of polyaluminium chloride The key technology, investigated the influence of different factors on the preparation process of aluminum chloride polymerization, under the optimized conditions, bridging calcium promote efficient aluminum ion polymerization, polymerization aluminum chloride products in Al_2O_3 content as high as 11%, the basicity is 76%, density is 1.1g/mL, the performance indexes meet the requirement of the national standard. The development and ash of controlled fabrication of silicon key technology of mullite, investigated the influence of different factors on the key indicators of mullite bulk density and porosity, under the optimized conditions, the mullite grain growth rodlike mullite, the mullite alumina content of stone products is higher than 70%, the volume density is higher than 2.85g/cm3, the porosity is less than 0.5%, the performance indexes meet the requirements of the national standard. On the basis of the whole process of material balance calculation, material flow analysis and preliminary economic evaluation, provide key basic data for engineering scale-up.

【学位授予单位】：中国科学院大学(中国科学院过程工程研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ175.6

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