The spent carbon cathode (SCC) produced in the aluminum electrolysis process has been listed as hazardous waste due to excessive soluble fluoride and cyanide. In a high-temperature vacuum environment, the soluble fluoride and cyanide in SCC can be evaporated and decomposed, respectively. As a result, its impact on the environment can be eliminated. The remains and volatiles can be collected for resource use. Based on the analysis of SCC chemical composition and phase structure, thermodynamic parameters of evaporation reactions were calculated by FactSage. The effects of treatment temperature and particle size of SCC on the removal of soluble fluoride and cyanide were further investigated by experiment. A suitable treatment condition, in which SCC particle size is 1.000–3.000 mm, at 1000 ºC for 2 h at vacuum conditions of 10 Pa, was obtained. The removal rate of soluble fluoride and cyanide in treated SCC reached 91.10% and 99.33%, and carbon content reached 89.89%. Combined with the analysis of TG-DSC and particle profile scan, the evaporation reaction mechanism by high-temperature vacuum treatment (HTVT) was analyzed. The work will be helpful for the development of new SCC treatment process.

Graphical Abstract

中文翻译：

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铝电解废碳阴极的高温真空处理

铝电解过程中产生的废碳阴极（SCC）由于含有过量的可溶性氟化物和氰化物，已被列为危险废物。在高温真空环境下，SCC中的可溶性氟化物和氰化物可以分别蒸发和分解。因此，可以消除其对环境的影响。可以收集残留物和挥发物以供资源使用。在分析SCC化学成分和相结构的基础上，利用FactSage计算了蒸发反应的热力学参数。通过实验进一步研究了处理温度和SCC粒径对可溶性氟化物和氰化物去除的影响。获得了合适的处理条件，其中 SCC 粒径为 1.000-3.000 mm，在 1000 ºC 和 10 Pa 的真空条件下处理 2 小时。处理后的SCC中可溶性氟化物和氰化物的去除率分别达到91.10%和99.33%，碳含量达到89.89%。结合TG-DSC分析和颗粒轮廓扫描分析，分析了高温真空处理（HTVT）的蒸发反应机理。该工作将有助于开发新的SCC治疗工艺。

图形概要