Na2O·xAl2O3的制备及其在低温电解质中的溶解及电解过程基础研究

低温铝电解有利于实现惰性电极铝电解技术的产业化应用，但它面临的最大难题是氧化铝在电解质中溶解速度太慢，跟不上电解消耗的速度。本项目创新性的提出采用Na2O·xAl2O3（x为30-110）为铝电解的原料以提高氧化铝在低温电解质中的溶解速度，实现700-760℃下的低温铝电解。首先在不同条件下制备出Na2O·xAl2O3并进行压片，研究其在低温电解质中的氧化铝溶解度和溶解速度，得出氧化铝溶解动力学参数；开展定量下料的电解实验考察氧化铝溶解速度是否满足电解需要并研究钠的阴极行为，得出合适的Na2O·xAl2O3制备工艺、电解质成分及电解工艺参数；采用高温拉曼光谱及定氧仪氧吸收峰对溶解过程中熔盐结构进行分析，结合实验数据研究熔盐结构和氧化铝溶解性能之间的关系，阐明Na2O·xAl2O3在低温电解质中的溶解机理及其溶解速度加快的原因。本项目研究成果将为低温铝电解的工业化应用提供理论支持和技术指导。

Aluminum electrolysis at low-temperature is conducive to the commercial application of carbon-free aluminum smelting technology based on inert electrode. The biggest problem faced by low temperature aluminum electrolysis is that the dissolution rate of alumina is too slow to keep up with the speed of electrolysis consumption. The innovative proposal of this project is to use Na2O·xAl2O3 (x=30-110) as the raw material of aluminum electrolysis to improve the dissolution rate of alumina in low temperature electrolyte, and realize low temperature aluminum electrolysis at 700-760℃. Firstly, Na2O·xAl2O3 will be prepared at different conditions, then pressed into tablet which will be used to study alumina solubility in electrolyte, and the dissolution kinetics parameters will be obtained. The electrolysis experiment will be carried out to investigate whether the dissolution rate of alumina could meet the need of electrolysis, and the cathodic behavior of sodium will also be studied as well. Based on those results, the suitable preparation method of Na2O·xAl2O3, electrolyte composition and electrolysis process parameters will be obtained. Molten salt structure will be analyzed by high temperature Raman spectroscopy. The relationship between molten salt structure and alumina solubility will be studied by analysis those information of molten salt structure and the Na2O·xAl2O3 dissolution experimental data. Based on the relationship, the reason why the dissolution rate of Na2O·xAl2O3 accelerates in low temperature electrolyte will be explained, and the dissolution mechanism will be also clarified. The research results of this project will provide basic theoretical and technical support for the industrial application of low-temperature aluminum reduction technology.