从含铬铝泥中回收铝的新工艺

采用"打浆水洗除Cr(Ⅵ)—电渗析除Cr(Ⅵ)—碱浸提铝—碳酸化分解法精制Al_2O_3"的新工艺处理含铬铝泥(以下简称铝泥),并回收Al_2O_3。实验结果表明:铝泥在70℃下经3次打浆水洗后,w(Na_2CrO_4)(以干铝泥计)降至5.0%;采用电渗析除Cr(Ⅵ)工艺可有效去除铝泥中以结合态和结晶态形式存在的Na_2CrO_4,在55 V直流电压下电渗析6h后铝泥中的w(Na_2CrO_4)降至0.98%;在碱浸温度为100℃、碱浸时间为3 h、NaOH质量浓度为150 g/L的优化碱浸条件下,铝浸出率(以Al_2O_3计)高达90.0%;经3次碳酸化分解处理后,Al_2O_3产品的纯度达98.65%,满足GB/T 24487-2009《氧化铝》中的一级标准,Al_2O_3回收率为96.37%。

A new process for recover aluminum from chromium-containing aluminum residue

The chromium-containing aluminum residue was treated to recover Al2O3 by a new process of beating and water-washing for Cr(Ⅵ)removal-electrodialysis for further Cr(Ⅵ)removal-alkali leaching for aluminum removal-carbonation decomposition for Al2O3 refinement. The experimental results show that:After beating and water-washing for 3 times at 70℃,w(Na2CrO4)(based on dried aluminum residue)of the residue can be reduced to 5.0%;The binding state and crystalline state Na2CrO4 in the residue can be effectively removed by electrodialysis,and w(Na2CrO4)of the residue can be reduced to 0.98%in 55 V DC voltage after electrodialysis for 6 h;Under the optimum alkali leaching conditions of alkali leaching temperature 100℃,alkali leaching time 3 h and NaOH mass concentration 150 g/L,the leaching rate of aluminum (calculate by Al2O3)is up to 90.0%;After 3 times of carbonation decomposition,the purity of Al2O3 product reaches 98.65%,which meets the first grade standard of GB/T 24487-2009,and the recovery rate of Al2O3 is 96.37%.