Selective Extraction of Cu(II) from Sulfuric Acid Leaching Solutions of Spent Lithium Ion Batteries Using Cyanex 301

Abstract

Spent lithium ion batteries contain cobalt, copper, lithium, manganese and nickel. Recovery of these metals with high purity from spent lithium ion batteries is of importance. A sulfuric acid solution is generally employed for the treatment of spent lithium ion batteries, but it is difficult to separate these metal ions from the leaching solution because the divalent metal ions have similar extraction behaviors. Once Cu(II) is separated from the sulfuric acid leaching solution, the traditional solvent extraction process for the separation of Co(II) and Ni(II) can be applied to the raffinate. Therefore, selective extraction of Cu(II) was investigated in this work using Cyanex 301. The effect of the concentration of sulfuric acid and Cyanex 301 was investigated. Within the sulfuric acid concentration range (pH 5-2.0 M) employed in this work, Cu(II) was completely extracted by Cyanex 301, while the extraction percentage of other metal ions decreased to negligible when the sulfuric acid concentration increased to 2.0 M. The addition of TBP to Cyanex 301 depressed the extraction of other metal ions except Cu(II) at an initial pH of 3, facilitating the selective extraction of Cu(II). The McCabe-Thiele extraction diagram indicates that most of the Cu(II) was extracted by two count-current extraction at an A/O ratio of 2. The Cu(II) loaded in Cyanex 301 was completely stripped by using 5% aqua regia. Key words: spent lithium ion batteries, sulfuric acid, Cyanex 301, copper(II), extraction