“钠化焙烧—水浸—分级沉淀”法从废铝基催化剂中提取分离铝、钒、钼的机理研究

Spent alumina-based catalyst is a kind of important second resource, using alumina as the carrier and vanadium, molybdenum as active constitutent, but which can not be regenerated. Comprehensive utilization of spent catalyst shows great economic and environmental significance, not only for avoiding unacceptable drains of valuable metals, but also for alleviating environmental pollution.During the past decade, considerable research was devoted to extract V and Mo from spent catalyst, but the main body of catalyst, carrier alumina, failed to achieve a meaningful recovery. In order to comprehensively recyle aluminum and other valuable metals from spent catalyst, a combined salt roasting-water leaching-step precipitation method was proposed in the present study. By the combination of theoretical analysis on thermodynamic, electrochemistry and solution chemistry, with metallurgical dynamics experiments and many modern measurment means,the transformation mechanism and procedure of Al, V, and Mo involving in the stage of roasting, leaching and separation will be studied. In the roasting and leaching stages, the transformation mechanism and dissolving behavior of Al, V, and Mo will be studied. In the separation stage, by the combination of theoretical analysis with the precipitation experiments of simulative systems, the reaction mechanism of Al, V, and Mo with Ca and Ba and its effect on separation behavior will be found out. By the orthogonal tests with a spent alumina-based catalyst,the main influencing factors and its regulation mechanism on the extraction of Al, V and Mo will be determined. The results obtained will contribute a theoretical basis to the extraction of valuable metals from spent catalyst, and a research foundation to realize the comprehensive utilization of spent catalyst as well.

废铝基催化剂是一种富含铝、钒、钼等有价组分的重要二次资源，对其进行综合回收利用，不仅避免了有用金属的大量流失，又减轻了对环境的污染，具有良好的经济和环境效益。前人研究工作集中在钒、钼等组分的回收，而废催化剂的主要组分-载体氧化铝却没有得到有效回收利用。本项目针对废催化剂中铝及其他有价组分的综合回收问题，提出"钠化焙烧-水浸-分级沉淀"的技术方法。采用热力学、电化学、溶液化学理论计算分析、动力学试验验证优化，并借助多种分析测试手段，研究废铝基催化剂钠化焙烧-水浸过程中铝、钒、钼的转化机制和溶解行为，揭示浸出液体系中铝、钒、钼与钙、钡的反应机理及其对分离行为的影响，确定影响铝、钒、钼提取和分离过程的主要因素及其调控机制，优化废催化剂中铝、钒、钼提取的技术途径。本研究为废催化剂中有价组分的提取提供理论基础，并为废催化剂实现综合利用奠定研究基础。

综合回收废铝基催化剂具有良好的经济和环境效益，前人研究工作集中在钒、钼等组分的回收，而废催化剂的主要组分—载体氧化铝却没有得到有效回收利用。本项目围绕废铝基催化剂中氧化铝的提取回收，系统研究其提取过程各主要组分的转化规律及分离机制，具有重要的理论意义和应用价值。. 项目通过理论与试验研究：（1）查明废催化剂中铝主要以α-Al2O3形式存在，明确了钠化焙烧对铝提取的必要性。（2）发现钠化焙烧过程中铝、钒、钼在不同的临界条件下可向各自的钠盐发生不同程度转化，铝在温度大于962.2K后才能与碳酸钠发生反应，生成的钠盐可以离子形态转入碱性介质；镍、钴则不与碳酸钠发生反应，以氧化物或氢氧化物的固体形态存在于碱性介质中。这为废铝基催化剂钠化焙烧—浸出实现铝、钒、钼与镍、钴的分离提供了理论基础。（3）阐明碱性介质中铝、钒、钼与钙、钡的反应机理及其对分离行为的影响，钙将优先与VO43-发生反应，使钒与铝、钼分离；钡随后与MoO42-反应，使钼和铝分离。（4）提出了分级沉淀法从碱性介质中分离铝与钒、钼的新方案：即在铝酸钠溶液中分步加入CaO和BaAl2O4，钒、钼的沉淀率可分别达到97%和99%，铝与钒、钼的分离效果好，并使铝酸钠溶液得到深度净化。（5）综合理论分析与试验研究成果，总结归纳了废铝基催化剂“钠化焙烧—水浸—分级沉淀”过程机理和影响因素，并通过试验得到了验证。. 本项目研究成果不仅为废铝基催化剂中氧化铝的提取回收提供了一种新途径，而且为镍、钴等其他有价元素的进一步回收创造了极为有利的条件，对废铝基催化剂综合回收理论与技术的发展进步具有重要的促进作用。