高压碱浸法处理铝电解废旧阴极炭块

利用高压碱浸工艺处理废旧阴极炭块，研究了NaOH浓度、碱浸温度、液固比、反应时间对处理效果的影响，并通XRD、XRF、浸出毒性分析、SEM-EDS探索了废旧阴极炭块处理前后的物相组成、元素含量、浸出毒性、微观形貌和元素分布的变化规律。结果表明，随着NaOH浓度的增加，回收炭材料的碳纯度和F-浸出浓度分别呈现先增加后减小、先减小后增大的变化趋势，随着碱浸温度、液固比、反应时间的增加，回收炭材料的碳纯度逐渐增大，F-浸出浓度不断降低。在最佳工艺条件下，废旧阴极炭块的碳含量从60.02%提高至88.63%，氟浸出浓度含量从2 699.95 mg/L降低至22.19 mg/L，并成功利用碳酸化分解法从浸出液中提取冰晶石产品。高压碱浸工艺具备实现废旧阴极炭块无害化与资源化回收的技术可行性。

Treatment of Spent Carbon Cathodes from Aluminum Electrolysis by High Pressure Alkali Leaching

Spent carbon cathodes from aluminum electrolysis were treated by high pressure alkali leaching. Effects of NaOH concentration, alkali leaching temperature, L/S, and reaction time on treatment of spent carbon cathodes were studied. The changes of phase composition, element content, leaching toxicity, microscopic morphology, and element distribution of spent carbon cathodes before and after treatment were explored by XRD, XRF, leaching toxicity analysis, and SEM-EDS. The results show that with the increase of NaOH concentration, carbon purity and F- leaching concentration of recovered carbon rises first and then drops, and drops first and then rises, respectively. With the increase of alkali leaching temperature, L/S and reaction time, the carbon purity of recovered carbon rises gradually, and F- leaching concentration drops continuously. Under the optimal process conditions, carbon content of spent carbon cathodes rises from 60.02% to 88.63%, and fluoride ion leaching concentration drops from 2 699.95 mg/L to 22.19 mg/L, and the cryolite product is successfully extracted from leachate by carbonation decomposition method. High-pressure alkali leaching process is technically feasible to realize the harmless and resource recovery of spent carbon cathodes.