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由于锂离子电池具有安全环保,电池容量大,输出功率大,自放电小等诸多优点,被广泛用于便携式电子产品,航空航天,医疗器械等领域[1~2]。据报道,2022年中国锂电池正极材料和负极材料产量分别有1.85×106 t和1.4×106 t,而2022年锂电池回收量仅有4.15×105 t,只有15%不到的锂电池得到有效回收,因锂电池使用寿命只有1~3年,如果回收率不变,到2025年可能会有2.835×106 t废电池不能得到有效回收。这些废旧锂电池中含有钴、镍等有毒重金属,直接丢弃会对土壤、河流等造成严重污染,而锂离子电池中锂、镍、钴、锰等金属的含量远高于一般矿物,具有极高的资源性和价值,随着科技不断发展和资源的不断开发,对资源的可循环利用和环境保护的要求被日益重视[3],因此废旧锂离子电池的回收显得尤为重要并已经迫在眉睫[4-5]。
溶剂萃取法[6]因其具有高提取率、选择分离性高、流程简单和操作连续化等优点,已经成为处理废旧锂电池中金属离子分离回收的主要方法。目前废旧三元锂电池中有价金属提取主要是在无机酸 (硫酸、盐酸等)体系中进行,因此,萃取分离的研究重点主要在硫酸、盐酸等无机酸体系中开展。如:代梦雅等[7]对电极材料使用硫酸浸出,浸出液经过P204除锰,在pH=5.2条件下,分别以0.5 mol·L−1 P507和0.6 mol·L−1 Cyanex272为萃取剂,经过两级错流萃取,钴萃取率分别为98.21%和99.44%, 镍共萃取率分别为24.42%和4.26%, 锂共萃取率分别为15.84%和5.11%;鲁桃等[8]在硫酸体系中使用Cyanex272,初始pH为4,萃取剂体积分数为50%,皂化率75%左右,O/A=1∶1,振荡时间为2 min,钴的一级萃取率为98.38%,而镍的损失率为2.28%。但在无机酸体系提取过程中易产生Cl2、SO2等有害气体、设备易腐蚀、铜、铝等杂质浸出率高等缺点,近年来,更多研究选用酸性较为温和、更为环保、杂质浸出率低的有机酸对正极材料中有价金属进行浸出被越来越多的研究者所关注[9]。如孟飞[10]使用柠檬酸对废旧三元电池浸出,镍钴锂锰的浸出率均大于90%,而铜、铝的浸出率均小于30%;高桂兰[11]对正极材料在柠檬酸浓度1.2 mol·L−1、硫代硫酸钠浓度0.3 mol·L−1、固液比20 g·L−1、浸出温度70 ℃、浸出时间30 min,钴的浸出率可达96%左右,锂的浸出率可达99%左右;但目前,关于在有机酸体系萃取分离废旧三元锂电池中的有价金属的文献较少。
本研究选用的是有机酸中较为便宜的D, L-苹果酸浸出废旧锂电池正极材料,经过前期一定的探索实验探究有机酸体系各种萃取剂对有价金属元素的萃取率;对浸出液选用一种或几种萃取剂来对其中的锰和钴进行分步萃取,研究不同影响因素下萃取剂对苹果酸浸出液中金属元素的萃取效果,为有机酸体系高效萃取锰、钴提供一定的参考。
废旧锂电池正极材料浸出液中锰、钴的萃取分离
Extraction and separation of manganese and cobalt from the leaching solution of cathode materials of waste lithium batteries
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摘要: 针对废旧锂电池中正极材料中有价金属未得到有效回收的情况,对废旧锂电池正极材料用苹果酸浸出后的浸出液进行分步萃取,以回收其中有价金属。研究了萃取时间、相比O/A、萃取剂体积分数等因素对各金属元素萃取率的影响。结果表明:在最佳萃取条件下,用P204 经过三级逆流萃取后,锰的萃取率达到99.99%,镍、钴、锂的共萃率分别为12.11%、9.20%、3.23%。负载锰的有机相用含1 g·L−1锰的苹果酸溶液洗脱共萃取的镍、钴、锂,然后用300 g·L−1的苹果酸三级逆流反萃锰,锰的反萃率达到了88.80%;用Cyanex272为萃取剂通过三级逆流萃取,钴的萃取率达到了94.01%,锂、镍的共萃率分别为11.21%和0.02%,负载钴的有机相用含1 g·L−1钴的苹果酸溶液洗脱共萃取的锂,随后用30 g·L−1的苹果酸对负载钴的有机相进行三级逆流反萃,钴的反萃率达到了99.98%;提出了先用P204从废旧锂电正极材料苹果酸浸出液中萃取分离Mn,而后再用 Cyanex272萃取分离Co的工艺流程,可实现苹果酸浸出液中Mn和Co的分离。本研究结果可为有机酸体系高效萃取锰、钴提供参考。Abstract: In response to the situation that the valuable metals in the cathode materials of waste lithium batteries were not effectively recovered, fractional extraction of malic acid lechate was conducted to recover the valuable metals therein. The effects of extraction time, ratio O/A, and extractant volume fraction on the extraction rate of each metal element were investigated. The results showed that, after three-stage countercurrent extraction using P204 under the optimal extraction conditions, 99.99% manganese was obtained, while the co-extraction of nickel, cobalt and lithium was 12.11%, 9.20%, 3.23%, respectively. The co-extracted nickel, cobalt, lithium of manganese loaded organic phase were eluted with malic acid solution containing 1 g·L−1 manganese, and then manganese was stripping with three-stage countercurrent stripping of 300 g·L−1 malic acid, and the manganese stripping rate reached 88.80%. The extraction rate of cobalt reached 94.01% by three-stage countercurrent extraction using Cyanex272, 11.21% and 0.02% for lithium and nickel, respectively. The co-extracted lithium of cobalt loaded organic phase were eluted with malic acid solution containing 1 g·L−1 cobalt, and then cobalt was stripping by three-stage countercurrent with 30 g·L−1 malic acid, achieving 99.98% for cobalt. The process flowsheet was proposed first extracting and separating Mn from the malic acid leachate with P204 and then extracting and separating Co with Cyanex272, and the separation of Mn and Co from the malic acid leachate can be achieved. The results of this study can provide a reference for the efficient extraction of manganese and cobalt by organic acid systems.
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Key words:
- malic acid leachate /
- solvent extraction /
- P204 /
- Cyanex272
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