(1. 中国科学院绿色过程与工程重点实验室，中国科学院过程工程研究所，北京 100190；
2. 战略金属资源绿色循环利用国家工程研究中心，中国科学院过程工程研究所，北京 100190；
3. 中国科学院大学，北京 100049；
4. 东北大学 冶金学院，沈阳 110819)
摘 要: 二次铝灰是电解铝工业产生的一种含铝危险废弃物，由于成分复杂，其中的铝资源尚未得到有效利用。通过二次铝灰与硫酸铵混合焙烧形成易浸取的硫酸铝铵，可实现二次铝灰中铝资源的高效回收。本文采用热重-红外联用仪、XRD、SEM和HSC等研究了二次铝灰与硫酸铵焙烧提铝过程机理。结果表明：二次铝灰中主要含铝物相为Al2O3、AlN、Na3AlF6、Al和NaAl11O17，二次铝灰与硫酸铵混合物料的热分解过程可分为六个阶段。在30~215 ℃阶段，主要为物理水挥发；在215~300 ℃阶段，(NH4)2SO4分解为NH4HSO4并产生NH3；在300~337 ℃阶段，NH4HSO4开始分解为SO2、NH3、H2O；在337~437 ℃阶段，Al2O3与(NH4)2SO4反应生成NH4Al(SO4)2并产生NH3、H2O，含量相对较少的含铝物相(Al、AlN和NaAl11O17)及氟化物(Na3AlF6、CaF2)逐渐与硫酸铵反应生成相应的硫酸盐；在437~556 ℃阶段，NH4Al(SO4)2分解生成Al2(SO4)3、SO2、NH3、H2O；在556~900 ℃阶段，Al2(SO4)3分解生成Al2O3和SO2。因此，二次铝灰硫酸铵焙烧提铝优化温度区间为300~500 ℃。
关键字: 二次铝灰；铝资源；硫酸铵焙烧；过程机理
（1. CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
2. National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
3. University of Chinese Academy of Sciences, Beijing 100049, China;
4. School of Metallurgy, Northeastern University, Shenyang 110000, China）
Abstract:The secondary aluminum dross is one of Al-bearing hazardous wastes produced in the electrolytic aluminum industry. Due to the complex chemical composition of secondary aluminum dross, its aluminum resources have not been effectively utilized. The aluminum resources of secondary aluminum dross can be efficiently recovered by roasting with ammonium sulfate to form ammonium aluminum sulfate, which can easily dissolve into the water. In this paper, the process mechanism of aluminum extraction from secondary aluminum dross through roasting with ammonium sulfate was investigated by thermogravimetric-infrared spectroscopy, XRD, SEM and HSC. The results show that Al2O3, AlN, Na3AlF6, Al and NaAl11O17 are the main Al-containing phases in secondary aluminum dross. The thermal decomposition process of secondary aluminum dross and ammonium sulfate mixture can be divided into six stages. In the stage of 30-215 ℃, physical water gradually volatilizes. In the stage of 215-300 ℃, (NH4)2SO4 is decomposed into NH4HSO4 and NH3. In the stage of 300-337 ℃, NH4HSO4 decomposes and produces SO2, NH3, and H2O. In the stage of 337-437 ℃, Al2O3 reacts with (NH4)2SO4 to produce NH4Al(SO4)2, NH3, and H2O. Besides, Al-containing phases (Al, AlN and NaAl11O17) and fluorides (Na3AlF6, CaF2)) reacts with (NH4)2SO4 to form corresponding sulfates. In the stage of 437-556 ℃, NH4Al(SO4)2 is decomposed into Al2(SO4)3, SO2, NH3, and H2O. In the stage of 556-900 ℃, Al2(SO4)3 is decomposed into Al2O3 and SO2. Therefore, the optimum temperature range of the process is from 300 ℃ to 500 ℃.
Key words: secondary aluminum dross; aluminum resources; ammonium sulfate roasting; process mechanism
