硫酸/草酸体系下拜耳法赤泥中铁铝浸出行为的差异

Differential Leaching Behavior of Iron and Aluminum from Bayer Red Mud in Sulfuric Acid Oxalic Acid System

为探清赤泥中的Fe、Al在硫酸草酸体系中浸出行为差异,比较研究了两种酸浸体系下广西某铝厂拜耳法赤泥中Fe、Al的浸出规律及机制。主要考察了酸浸过程因素对Fe、Al浸出效果的影响,比较分析了最佳试验条件下拜耳法赤泥中Fe、Al在不同酸浸体系的浸出差异,并通过浸出动力学和热力学分析阐述了硫酸草酸体系下Fe、Al的浸出过程机理。研究表明,试验条件下,硫酸对Fe、Al的浸出效果均优于草酸;酸性溶液中赤泥各元素的浸出具有阶段性,其中Al的浸出优先于Fe;硫酸草酸体系中对Fe浸出的效果差异主要体现在无机酸酸根和有机酸酸根供电子能力和作用机制不同,对Al浸出的效果差异主要体现在对赤泥中铝氧化物的作用机制不同。这一发现对充分利用不同酸处理赤泥、优化分离提取赤泥中有价金属提供了新思路。

Leaching pattern and mechanism of iron and aluminum in Bayer red mud from an aluminum plant in Guangxi under sulfuric acid oxalic acid leaching systems were researched.The effects of acid leaching process factors on leaching effect of iron and aluminum were examined.The leaching differences of iron and aluminum in different acid leaching systems under the optimal test conditions were compared.The mechanism of leaching process was also analyzed by leaching kinetics and thermodynamics.The results show that the effect of sulfuric acid on iron and aluminum is better than that of oxalic acid.The leaching of each element of red mud in acidic solution has stages,in which the leaching of Al is prior to that of Fe.The variability of the effect on iron leaching is mainly reflected in different electron donating capacity and mechanism of action for inorganic and organic acids.The variability of the effect on aluminum leaching is mainly reflected in different mechanisms of action on aluminum oxides.This discovery provides new research ideas to make full use of different acids to treat red mud and optimizes the separation and extraction of valuable metals from red mud.