电解剥离—生物质酸浸回收废旧锂离子电池中的钴

发布时间：2018-02-28 11:37

  本文关键词： 废旧锂离子电池 正极材料 电解剥离 铝箔 浸出 燕麦秸秆　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：针对废旧锂离子电池正极材料回收中一些关键难题,论文提出电解剥离-生物质酸浸回收新工艺。研究采用硫酸柠檬酸为电解液,带铝箔的正极条为阴极,铂电极为阳极,电解剥离-浸出,实现了电池粉与铝箔剥离和部分钴的浸出。收集残余的浸出渣,采用燕麦秸秆粉为还原剂,用硫酸浸出渣中的钻。新流程避免了酸浸出过程铝箔的溶解带来的后续分离铝的难题,实现了铝箔的资源化回收,另外新流程不需双氧水为还原剂,过程简单经济安全。 论文研究了电解-硫酸剥离浸出工艺动力学过程,研究表明浸出前期(5-30min)符合缩核模型,表观活化能为7.32kJ/mol,后期(75-180min)为内扩散控制模型,表观活化能17.05kJ/mol。电解浸出实验发现,由于氧化铝膜的溶解和氢气泡的“吹动”,正极电池粉在20～30min从铝箔上剥落,此后,钴的浸出能力逐渐减弱,电流效率逐渐降低。电解剥离最优实验条件为：硫酸浓度20～30g/L,柠檬酸浓度36g/L,电流密度为200A/m2,电解剥离-浸出时间为30min。在此条件下可实现正极粉与铝箔的分离,钴的浸出率为40%左右,铝箔溶解约2%,电流效率40～50%。 对于电解剥离后残余的浸出渣,论文采用生物质燕麦秸秆粉代替双氧水作还原剂,用硫酸浸出。通过单因素实验,得到最佳工艺条件为：液固比为10,单位质量电池渣所需麦秆粉用量0.7g,硫酸浓度2mol/L,温度90℃,燕麦秸秆粉粒径为60～100目,电池渣中钻的浸出率在99%以上。为了降低浸出液中的COD,本文设计了三级酸浸工艺,结果浸出液中Co2+的浓度达到50g/L以上,而COD浓度降至1.5g/L左右。论文对生物质酸浸过程进行动力学研究,结果表明在浸出前期(0-20min)为缩核模型,而浸出后期(30～150min)受化学反应控制为主的缩核模型控制。浸出前后粉渣的FT-IR检测表明,燕麦秸秆粉含有丰富的木质素、聚木糖、纤维素和半纤维素等的还原性物质,在浸出过程能替代双氧水还原浸出钻。 浸出液采用草酸沉钴,工艺条件为：pH值1-2,温度50-60℃,沉降时间1h,[C2O42-]/[Co2+]比值控制在1.05～1.1左右,钴的沉降率达到92～95%,沉降得到草酸钴产品经分析合格。论文将草酸钻用于制备钴酸锂正极材料,通过XRD分析晶格参数发现,钴酸锂材料具有良好的电池性能。
[Abstract]:In view of some key problems in recovering cathode materials from waste lithium ion batteries, a new process of electrolytic stripping and recovery of biomass by acid leaching was proposed. Citric acid sulfate was used as electrolyte, positive electrode with aluminum foil as cathode and platinum electrode as anode. Electrolytic stripping and leaching of battery powder and aluminum foil and partial cobalt leaching were realized. Residual leaching slag was collected, and oat straw powder was used as reducing agent. The new process avoids the problem of the subsequent separation of aluminum caused by the dissolution of aluminum foil during acid leaching, and realizes the recovery of aluminum foil. In addition, the new process does not need hydrogen peroxide as reducing agent, and the process is simple, economical and safe. The kinetic process of electrolysis and sulfuric acid stripping leaching was studied in this paper. The results showed that the pre-leaching process was in accordance with the model of shrinking nucleus, the apparent activation energy was 7.32kJ / r / mol, the latter was 75-180min), and the apparent activation energy was 17.05kJ / mol. Due to the dissolution of aluminum oxide membrane and the "blowing" of hydrogen bubble, the positive electrode battery powder flakes off from the aluminum foil at 20 鈩，

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