摘要
The full alumina dissolution process in aluminum electrolysis cells was investigated using an improved computational fluid dynamics(CFD)model based on the previous researches by consideration of agglomerate formation.The results show that the total mass of alumina agglomerate and its maximum size are mainly dependent on the feeding amount and increase with increasing it.Higher superheat can effectively inhibit the agglomerate formation and thus promote the full alumina dissolution behavior.The full alumina dissolution process mainly includes a fast stage and a slow stage,with an average dissolution rate of 17.24 kg/min and 1.53 kg/min,respectively.About 50%(mass percentage)of the total alumina particles,almost all of which are the well-dispersed alumina fine grains,dissolve within the fast dissolution stage of about 10 s.The maximum values of the average dissolution rate and final percentage of the cumulative dissolved alumina mass are obtained with a feeding amount of 1.8 kg for a superheat of 12℃.The formation of the alumina agglomerates and slow dissolution characteristics play a dominant role in the full dissolution of alumina particles.
基于前期研究结果,改进和建立铝电解槽内氧化铝颗粒溶解全过程的数值计算模型,重点考虑氧化铝结块形成的影响。结果表明,氧化铝结块总质量和最大尺寸主要依赖于氧化铝的下料量,且随着下料量的增加而增大。电解质过热度越高,更容易抑制结块的形成,从而促进氧化铝颗粒溶解行为。氧化铝颗粒溶解全过程主要分为快速溶解阶段和缓慢溶解阶段,两者平均溶解速率分别为17.24 kg/min和1.53 kg/min。快速溶解阶段溶解时间大概持续10 s,且约有质量分数为50%的氧化铝颗粒(几乎全部为扩散特性好的氧化铝细颗粒)完全溶解。当下料量为1.8kg、过热度为12℃时,平均溶解速率和累计溶解质量百分数均达到最大值。氧化铝结块形成和缓慢溶解行为在氧化铝颗粒溶解全过程中起到主导作用。
基金
financial supports from the National Natural Science Foundation of China (No. 51704126)
the Natural Science Foundation of Jiangsu Province, China (No. BK20170551)
Jiangsu Planned Projects for Postdoctoral Research Funds, China (No. 2019K046)。
