铝电解槽废旧阴极内衬的回收利用

铝电解槽的阴极内衬由耐火材料和炭素材料砌筑而成。在电解过程中,由于电解质对碳阴极的渗透和腐蚀以及其他一些原因,电解槽工作3～4年后,便出现破损而被迫停槽大修,更换新的阴极内衬。在更换下来的废旧阴极内村中,约含有30％碳、30％耐火材料和40％氟化盐(主要是Na_3AlF_6、NaF、CaF_2等),且从氟平衡的调查测试结果得知,碳阴极中吸收了99％的氟化盐。废旧阴极内衬中的碳和氟化盐是两种有价值的材料。

Recovery of carbon and cryolite from spent pot lining of aluminium reduction cells by chemical leaching

A two-step alkaline-acidic leaching process was conducted to separate the cryolite from spent pot lining and to purify the carbon. The influencing factors of temperature, time, and the ratio of liquid to solid in alkaline and acidic leaching were investigated. The results show that the recovery of soluble compounds of Na3AlF6 and Al2O3 dissolving into the solution during the NaOH leaching is 65.0%,and the purity of carbon reaches 72.7%. During the next step of HCl leaching, the recovery of soluble compounds of CaF2 and NaAl11O17 dissolving into the HCl solution is 96.2%, and the carbon purity increases to 96.4%. By mixing the acidic leaching solution and the alkaline leaching solution, the cryolite precipitates under a suitable conditions of pH value 9 at 70 °C for 2 h. The cryolite precipitating rate is 95.6%, and the purity of Na3AlF6 obtained is 96.4%.

工业铝电解系统节能技术开发实践

电解铝企业可操作、持续、有效、大幅度的取得节能减排经济效益的关键指标是阳极炭耗及运行电耗、吨铝电耗和吨铝分摊大修成本。由于电解铝技术的综合性特点,采用铝电解系统性节能减排技术创新,符合国家行业和企业竞争的生存需要。基于此,本文主要阐释了这几项技术的基本背景、特点和创新效益的原理及应用案例。

铝电解废旧阴极盐酸浸出动力学分析

以铝电解槽废旧阴极为研究对象,针对两步浸出法工艺,用收缩核模型研究了碱浸出后的废旧阴极内衬固体用HCl溶液浸出NaAl11O17动力学。考察了粒径大小、不同温度和搅拌速度对浸出率的影响,并建立了反应的动力学方程。结果表明,该浸出反应的控制环节为内扩散,反应表观活化能为18.26 kJ/mol。生产中最佳工艺条件为:浸出温度85℃、搅拌速度600 r/min、粒径0.075 mm。该工作为铝电解槽废旧阴极内衬规模化利用打下了坚实的基础。