沉降加过滤去除回收铝罐料中Fe杂质工艺研究

Research on the Process of Sedimentation Add Filtration to Remove Fe Impurities from Recycled Aluminium Cans

废铝回收再利用可极大节约能源,但由于多种原因其回收时往往会混入杂质Fe元素,从而极大损害铝合金力学性能。因此,开发一种有效再生铝除Fe技术对于推动废铝回收行业的发展具有重要意义。本文以含Fe量为1.4%(质量分数)的回收铝罐料为研究对象,通过添加Mn、Si元素在熔体中形成粗大All5(Fe,Mn)_(3)Si_(2)相,进而采用沉降+过滤工艺对其进行除Fe研究。结果表明,当向铝熔体中添加2.98%Mn和7.89%Si(质量分数),且在630℃保温沉降15 min后进行过滤,可获得最佳除Fe效果,其沉降除Fe率和过滤除Fe率分别达到64.5%、68.8%。微观组织分析表明,沉降可去除坩埚底部偏聚的大量枝晶状All5(Fe,Mn)_(3)Si_(2)相,过滤可去除熔体上部存有的少量块状All5(Fe,Mn)_(3)Si_(2)相;上部熔体经过滤后,陶瓷过滤片中残留一定量的块状All5(Fe,Mn)_(3)Si_(2)相,而熔体中则含有少量的鱼骨状All5(Fe,Mn)_(3)Si_(2)相。

Recycling and reusing scrap aluminium can greatly save energy.However,for a variety of reasons,the impurity Fe is often mixed during recovery,which greatly deteriorates the mechanical properties of aluminium alloys.Therefore,developing an effective Fe removal technology for recycled aluminium is highly important for promoting the development of the scrap aluminium recycling industry.In this study,recycled aluminium cans with an Fe content of 1.4 wt.%were taken as the research object.By adding Mn and Si,a coarse All5(Fe,Mn)_(3)Si_(2) phase was formed in the melt,and then,Fe removal was investigated via a sedimentation+filtration process.The results show that the best Fe removal effect is obtained by adding 2.98 wt.%Mn and 7.89 wt.%Si to the aluminium melt and then filtering after being kept at 630℃for 15 min.The Fe removal rates by sedimentation and filtration can reach 64.5%and 68.8%,respectively.Microstructure analysis reveals that sedimentation removes a large amount of the dendritic All5(Fe,Mn)3Si phase segregated at the bottom of the crucible,and filtration removes a small amount of the block-like All5(Fe,Mn)3Si phase in the upper part of the melt.After the upper melt is filtered,a certain amount of the block-like All5(Fe,Mn)3Si phase remains in the ceramic filter,whereas a small amount of the fishbone-shaped All5(Fe,Mn)3Si phase is contained in the melt.