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煤气化作为一种煤炭转化技术得到迅速发展，其利用过程产生大量煤气化渣，现有的利用技术潜在环境危害大。煤气化渣中含有丰富的铝、硅和碳资源，若能实现大规模资源化利用，不但可以破解环境污染问题，更可以有效减少原生矿产开采。本文以鄂尔多斯某厂煤气化细渣为研究对象，开展了气化渣的矿相结构、元素分布与灰渣特性系统分析，明确了气化渣矿相结构特点、元素赋存规律和灰渣反应活性。提出了循环酸活化-稀碱脱硅制备高模数硅酸钠溶液联产聚合氯化铝的技术思路，系统开展了工艺优化研究。进一步结合29Si固体核磁与颗粒孔道结构表征等研究手段明晰了气化渣活化与脱硅机理。主要结论如下：（1）开展了煤气化渣原样分析，明确鄂尔多斯地区煤气化渣物化特征。该气化细渣中无机组分铝硅含量可达45%，碳含量可达30%左右，矿相以非晶态铝硅酸盐为主，含有少量石英相与方解石等。大部分细渣粒径分布在10?100 μm之间，颗粒形貌主要为不定型絮状碳和不规则无机颗粒两种，颗粒间相互夹杂。铝硅与杂质元素均匀分布在无机颗粒表面，部分铁钙元素存在富集。（2）开展了循环酸浸-聚合调控制备聚合氯化铝工艺优化，明确循环酸浸最佳工艺条件。进一步开展活化机理研究，明确铝及其他杂质离子的浸出导致颗粒孔道被打开，结构发生了较大的变化，比表面积高达279.52 m2/g，颗粒微孔与介孔比表面积为44.44 m2/g和235.07 m2/g。颗粒的铝硅配位结构由Q4（2Al）转变为Q4（1Al），铝和铁钙等杂质进入到液相中后，颗粒表面的Si?O?Al、Si?O?Ca等化学键转变为活性更高的Si?O?H键。针对富铝酸液氧化铝含量高，盐基度偏低的特点，提出了聚合调控制备聚合氯化铝的思路，并开展了聚合调控工艺优化，在最优条件下可制备得到氧化铝含量大于10%，盐基度大于30%的聚合氯化铝产品。（3）针对酸活化后酸浸渣活性较高的特点，提出了酸浸渣稀碱脱硅思路，开展了脱硅过程工艺优化，在最佳工艺条件下，可以制得模数达3.5的硅酸钠溶液。与未经酸活化的直接脱硅相比，活化脱硅的脱硅率提高56.3%。脱硅渣中含有大量形貌较优良的沸石，比表面积达323.43 m2/g，颗粒微孔与介孔比表面积分别为45.48 m2/g和289.04 m2/g。 （4）考察了脱硅渣的颗粒形貌与种类，明确200目筛上物碳含量较高，颗粒以较大、不规则的絮状碳颗粒为主，筛下物碳含量较低，颗粒形貌较为复杂。提出残碳分质利用的思路，将高碳渣用于气化炉循环掺烧。进一步开展了低碳渣预烧制备发泡陶瓷研究，考察了不同原料配比、焙烧温度、焙烧时间对气化渣发泡陶瓷性能的影响。 ;Coal gasification, as a kind of coal conversion technology, has been developed rapidly. This process will produce a large number of coal gasification slag, and the potential environmental harm will be great. There are abundant Al?Si?C resources in coal gasification slag. The large?scale utilization of it can effectively solve the problem of environmental pollution and reduce the exploitation of primary mineral. In this paper, a systematic analysis of the Erdos coal gasification fine slag including that mineral phase structure, element distribution and characteristics of gasification slag was carried out. The characteristics of gasification slag phase, the distribution of element and the reactivity of ash slag were clarified. The technical idea of producing polyaluminum chloride and high modulus sodium silicate solution by cyclic acid activation and dilute alkali desilication was put forward, and the optimization of this process was carried out. The mechanism of activation and desilication of gasification slag was further clarified by 29Si solid state NMR and particle pore structure analysis. The main conclusions are as follows:(1) The analysis of the original slag from Erdos was carried out, and it’s physical and chemical characteristics have been clarified. Results show that the main component is Al and Si with its concentration up to 45% and the content of C could reach to 30%. Amorphous aluminosilicate is the main mineral phase while some quartz and calcite exist in the slag. The particle size is mainly between 10 μm and 100 μm. The morphology of the particles is mainly amorphous carbon and irregular inorganic particles. The element of Al, Si and impurity elements are uniformly distributed on the surface of inorganic particles, some elements enriched in the slag.(2) The optimization of cyclic acid leaching process for the preparation of polyaluminum chloride was carried out and the optimal process conditions were clarified. Further study on activation mechanism was carried out. It is clear that the leaching of aluminum and other impurity ions cause the openning of the particle pores. The structure of the particles is changed greatly with specific surface area of 279.52 m2/g, and the specific surface area of micropores and mesoporous particles is 44.44 m2/g and 235.07 m2/g, respectively. The Al-Si coordination structure of the original particles changes from Q4 (2Al) to Q4 (1Al). When Al and the impurity elements Fe and Ca enter into the liquid phase, the chemical bonds that Si?O?Al and Si?O?Ca on the surface of the particles are transformed into more reactive bond that Si?O?H. Based on the characteristics of high alumina content and low basicity in high aluminate solution, the process of preparing polyaluminum chloride was put forward and optimized. The polyaluminum chloride product with aluminum content more than 10% and basicity exceeding 30% can be prepared.(3) According to the high reactivity of acid activation slag, a dilute alkali desilication process of acid activation slag was put forward and optimized. Sodium silicate solution with a modulus of 3.5 can be prepared. Compared with the direct desilication without acid activation, the desilication ratio of activated slag was improved to 56.3%. Desilication slag contains a large number of zeolite with excellent morphology. The specific surface area is 323.43 m2/g, The specific surface area of micropores and mesoporous particles are 45.48 m2/g and 289.04 m2/g, respectively.(4) The morphology and species of the particles were investigated. The carbon content over 75 μm was higher. The large size and the irregular carbon particles were main particle in it. The carbon content under 75 μm was lower, and the morphology of the particles was complicated. The utilization of residual carbon was put forward. High carbon slag can be used for circulating combustion. Further research on the preparation of foamed ceramics was carried out. The effects of different raw materials, calcination temperature and calcination time on the properties of foamed ceramics were studied. Based on the optimization of the whole process, the material balance estimation of the process is carried out.
|胡文豪. 煤气化渣铝硅组分活化分离与资源化利用基础研究[D]. 中国科学院大学,2019.|
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