Separation Of Lithium-Cobalt-Nickel By Precipitation-Extraction Method Based On Organic Amine And The Preparation Of Lithium

The development of lithium battery recycling technology is the only way to sustainable resources and environment.Due to the complex composition of lithium battery,the recovery steps generally include pretreatment,leaching of electrode materials,separation and recovery of metal ions,among which the separation and recovery of metal ions is the key step to recover single metal ions from the complex composition of the leaching solution.The chemical precipitation method is the most commonly used method in the separation and recovery of metal ions because of its advantages of simple operation,fast reaction rate and high separation efficiency.More types of separators are generally introduced,which will lead to the introduction of excessive impurity ions and subsequent wastewater treatment difficulties.At the same time,in order to increase the recovery rate of metal ions,it is common to introduce excessive separators,which cannot be recycled and increases the difficulty of subsequent wastewater treatment.In addition,Li is generally recovered by adding saturated sodium carbonate solution to prepare lithium carbonate（Li₂CO₃）,but there are problems such as low recovery of Li and poor crystal morphology of Li₂CO₃.Based on this,this paper proposes separation of lithium-cobalt-nicket by precipitation extraction method based on organic amine and the preparation of Li₂CO₃.An organic amine was co-precipitated with Co and Ni at a low concentration to separate Li element,and then high concentration amine was added to the co-precipitate to selectively extract Ni element to achieve the separation of Co and Ni.Li₂CO₃was prepared by CO₂mineralization into amine-Li solution.In this process,only one organic amine is introduced as a multifunctional separation agent,which theoretically reduces the difficulty of subsequent wastewater treatment and solves the problem of introducing too many impurity ions.It achieves the green separation of Li,Co,Ni.This paper mainly studied the feasibility of co-precipitation with Co and Ni to separate Li by organic amine at low concentration,the feasibility of selective extraction separation of Co and Ni at high concentration,the feasibility of the whole process of precipitation extraction separation of Li,Co and Ni,and amine enhanced CO₂mineralization and Li₂CO₃preparation.The main research results are as follows:（1）2-amino-2-methyl-1-propyl alcohol（AMP）,triamino-propyl alcohol（MPA）,diethylaminoethanol（DMAP）and dimethylethanolamine（DMEA）as separation agents could achieve the purpose of separating Li by co-precipitation of Co and Ni.When the concentration of amine is 0.4 mol/L,Co and Ni in the solution with the concentration of0.1 mol/L can be precipitated completely.In this process,the complexation effect of amino with Co and Ni in organic amines is much greater than that of Li,resulting in co-precipitation of Co,Ni and organic amines,and separation of Li in solution.（2）AMP and MPA could selectively extract Ni,and the leaching amount increased with the increase of concentration.At the same concentration,the leaching amount of AMP is larger,and the leaching selectivity of MPA is better for Ni.The extraction effect was the best when AMP concentration was 2 mol/L protonation to 0.7.The leaching amounts of Co and Ni were 0.0128 mol/L（12.8%of total amount）and 0.1 mol/L（basically complete leaching）,respectively.This may be because the introduction of H⁺will combine with amino group to form a more stable protonated amino group,which increases steric hindrance and enhances extraction effect.（3）The Li recovery of Li₂CO₃prepared from Li OH without any additive was 77.1%by CO₂mineralization,and the addition of amine increased the Li recovery.Among the selected amines,the recovery rate of triethanolamine was the highest（93.1%）.This may be because triethanolamine are tertiary amines,which snatch protons from the solution and catalyze the formation of HCO₃^-,thus promoting the precipitation of Li₂CO₃.In contrast,proline in solution reduces Li recovery due to its acidic properties.（4）The feasibility of AMP and MPA separation of Li,Co and Ni by precipitation extraction was verified.The recoveries of Li,Co and Ni were 98.5%,79.3%and 96.8%,respectively.The cations of the three elements in the separation phase were 95.632%,99.4%and 85.1%,respectively.The recoveries of Li,Co and Ni were 97.8%,93.6%and91.1%,respectively.The cations of the three elements in the separation phase were 99.3%,91.1%and 92.2%,respectively.The results show that the separation of lithium cobalt nicket by precipitation extraction method based on organic amine and the preparation of lithium carbonate can provide a new idea and reference for the separation and recovery of Li,Co and Ni and the preparation of high-value Li₂CO₃.