ABSTRACT

The recovery of valuable metals in spent lithium-ion batteries (LIBs) is not only environmentally sustainable but also economically advantageous. In this research, ammoniacal leaching process was adopted to selectively extract valuable metals from the mixed types of cathode active materials. By employing the ammonium sulphite as the reductant, while the ammonia and ammonium carbonate are used to provide NH₃ to complex metal elements. The Eh–pH diagrams were used to study the extraction behaviour of Co, Li, Ni and Mn during ammoniacal leaching, and the Co, Ni can be leached out as the complexes ([Ni(NH₃)_n]²⁺, [Co(NH₃)_m]²⁺), while the Li was leached out as metallic ion. Manganese is first leached out as [Mn(NH₃)_β]²⁺ and then precipitated as (NH₄)₂Mn(SO₃)₂·H₂O and (NH₄)₂Mn(SO₄)₃ when an excess of ammonium sulphites added to the solution. A detailed understanding of the ammoniacal selective leaching process is carried out by investigating the effects of factors such as reaction temperature (50–90 ℃), leaching time (2–6 h), agitation intensity (400–900 rpm) and solid-to-liquid ratio (10–50 g/L). The experiment of response surface methodology shows that significant interactions exist between ammonium sulphite and ammonium carbonate, ammonium sulphite and ammonia according to the leaching efficiency of Co. Under the optimum conditions, Co, Li, Ni, Mn and Al can be leached out with the efficiencies of 84.56%, 90.31%, 64.13%, 4.53% and 1.72%, respectively. The results proved the possibility of selective leaching. Summarily, this research is potentially beneficial for the design of a selective recycling technique.

摘要

从废锂离子电池 (LIB) 中回收有价值的金属不仅具有环境可持续性，而且具有经济优势。在这项研究中，采用氨浸工艺从混合类型的正极活性材料中选择性地提取有价金属。以亚硫酸铵为还原剂，氨和碳酸铵为络合金属元素提供NH _{3 。}利用Eh-pH图研究了Co、Li、Ni和Mn在氨浸过程中的萃取行为，Co、Ni可以以络合物([Ni(NH ₃ ) _n ] ²⁺ , [Co (NH ₃ ) _m ] ²⁺), 而 Li 作为金属离子被浸出。_{锰首先以 [Mn(NH 3} ) _β ] ²⁺的形式浸出，然后以 (NH ₄ ) ₂ Mn(SO ₃ ) ₂ ·H ₂ O 和 (NH ₄ ) ₂ Mn(SO ₄ ) _{3的形式沉淀}当向溶液中加入过量的亚硫酸铵时。通过研究反应温度（50-90 ℃）、浸出时间（2-6 h）、搅拌强度（400-900 rpm）和固体对等因素的影响，详细了解了氨选择性浸出过程- 液体比 (10–50 g/L)。响应面法实验表明，根据Co的浸出效率，亚硫酸铵与碳酸铵、亚硫酸铵与氨之间存在显着的相互作用。在最佳条件下，Co、Li、Ni、Mn和Al可以用效率分别为 84.56%、90.31%、64.13%、4.53% 和 1.72%。结果证明了选择性浸出的可能性。总之，这项研究可能有利于选择性回收技术的设计。