基于碳酸钠熔融铝硅酸类废弃物的反应机制及其应用

Coal fly ash (CFA) and coal gangue (CG) as one of the largest industrial solid wastes contain large amount of alumina. Al2O3 extraction from them is one of the most important value-added utilization ways, which is of importance on alleviation of the shortage of bauxite resource. Sodium carbonate melting-acid leaching technology used to treat CFA and CG shows a good application prospect owing to the attainment of the value-added utilization of Al and Si simultaneously. The shortage in the basic theory for the technology, however, restricts the optimization and the industrial application of the technology. Based on CFA and CG having the common characteristic of the aluminum silicate wastes, the new idea is raised in this study which using sodium carbonate melting method to treat various aluminum silicate wastes. Moreover, mullite, kaolin and feldspar will be used to replace the complex aluminum silicates such as CFA and CG. The general rule of the melting reaction between sodium-containing substances with aluminum silicates will be revealed by discussing the key scientific problems, such as the melting mechanism of Na2O-Al2O3-SiO2 system, the mechanisms of the reaction between sodium carbonate and various aluminum silicates and between various sodium-containing matters with aluminum silicates. This study can provide the theoretical guidance to the establishment and the optimization of the technology used to treat various aluminum silicates wastes by sodium-containing melting.

粉煤灰、煤矸石是我国产生量最大的工业固体废弃物之一，内含丰富的氧化铝，从其中提取氧化铝作为其高值化利用的重要途径之一，对缓解我国铝资源的短缺有重要意义。碳酸钠熔融活化-酸浸工艺用于处理粉煤灰、煤矸石可实现铝、硅的同步高值利用，显示出良好的应用前景。然而，由于对该过程基础理论方面的认识不足，大大限制了对工艺的优化和该技术的工业化应用。本项目基于粉煤灰和煤矸石均为铝硅酸类废弃物的特点，提出可利用碳酸钠熔融处理其它各种铝硅酸类废弃物的新思路，并以莫来石、高岭石、长石等为模型矿物代替粉煤灰、煤矸石等复杂的铝硅酸矿物，通过探讨Na2O-Al2O3-SiO2熔融体系反应机制、碳酸钠与不同铝硅酸类矿物的作用机制以及不同含钠物质与铝硅酸矿物发生熔融反应的作用机制等关键科学问题，揭示铝硅酸类矿物在含钠助剂作用下发生熔融反应的普遍规律，为钠助剂熔融处理铝硅酸类废弃物技术工艺的建立与优化提供理论指导。

粉煤灰、煤矸石是我国产生量最大的工业固体废弃物之一，内含丰富的氧化铝，从其中提取氧化铝作为其高值化利用的重要途径之一，对缓解我国铝资源的短缺有重要意义。碳酸钠熔融活化-酸浸工艺用于处理粉煤灰、煤矸石可实现铝、硅的同步高值利用，显示出良好的应用前景。然而，由于对该过程基础理论方面的认识不足，大大限制了对工艺的优化和该技术的工业化应用。本项目针对Na2CO3熔融-酸浸处理铝硅酸废弃物工艺中存在的关键技术和科学问题，研究了粉煤灰、煤矸石等铝硅酸类废弃物在Na2CO3作用下的活化行为，探讨了Na2CO3对不同铝硅酸类矿物的分解及转化机制，研究了Na2SO4、NaCl、Na2B4O7•10H2O等不同含钠物质与粉煤灰、煤矸石等铝硅酸类废弃物发生熔融反应的作用机制，探究了Na2CO3对粉煤灰、煤矸石中模型矿物莫来石、高岭石等的反应机制等，揭示了铝硅酸类矿物在含钠助剂作用下发生熔融反应的普遍规律。在此基础上，针对Na2CO3熔融活化粉煤灰、煤矸石酸浸提取氧化铝技术中Na2CO3耗量大的问题，进行了优化工艺的探索，优化建立了粉煤灰预脱硅-Na2CO3活化酸浸以及赤泥协同活化粉煤灰、煤矸石两条优化工艺，显著降低Na2CO3消耗量，并针对这两条优化工艺开展了粉煤灰预脱硅和赤泥添加条件下粉煤灰、煤矸石中矿物内在转化机制的探讨。本项目研究过程中，发表国内外研究论文5篇，获得授权发明专利3项，参加国内国际会议多次，培养硕士研究生3名，在读博士生2名。