摘要
A novel process,which combined with citric acid reductive leaching,precipitation and extraction separation,was conducted with experiments which separated and recovered metal values such as Co,Mn,Ni and Li from the cathode active materials of the spent lithium-ion batteries.The leaching efficiency of Ni,Co,Mn and Li can reach 97.5%,98.1%,97.7% and 99.2% respectively under the optimal conditions of 1 M citric acid solution,80 ℃ leaching temperature,90 min leaching time,30 mlg-1 liquid-to-solid ratio and 2 vol.% H2O2.For the recovery process of the leach liquor,firstly Co was selectively reacted and precipitated as CoC2O4·2H2O with (NH4)2C2O4 under the optimum conditions of molar ratio of n(C2O42+):n(CO2+)=1.1∶1.0,equilibrium pH=3 and 60 ℃.Secondly,the Ni in the leaching liquor was selectively precipitated with dimethylglyoxime under the optimal conditions as pH=8 and the molar ratio of dimethylglyoxime to [Ni(NH3)6]2+ of 2.Thirdly,D2EHPA was used as extraction agent to separation Mn from the leach liquor.92% of Mn was extracted under the condition of 25vol.% D2EHPA ,O/A of 2 and pH=8.Finally,the remaining Li in the aqueous solution was readily recovered as Li2CO3 precipitated by the addition of a saturated Na2CO3 solution.The recovery rate of nickel,cobalt,manganese and lithium was 89%,91%,92% and 76%,respectively.