Selective extraction of metals using ionic liquids for nickel metal hydride battery recycling

Abstract

A new separation scheme for the recycling of metal values from nickel metal hydride batteries utilizing ionic liquids has been developed. The scheme has been optimized for synthetic solutions and uses either the ionic liquid trihexyl(tetradecyl)phosphonium chloride (Cyphos IL 101) or tricaprylmethylammonium chloride (Aliquat 336). In the first stage of extraction cobalt, manganese, iron and zinc are removed from the rare earths and nickel in a metal-loaded liquor of high chloride concentration (8 M chloride). Recovery of rare earths was demonstrated on the raffinate resulting from the first extraction by extraction with the solvating extractant Cyanex 923 (10% v/v) in tricaprylmethylammonium nitrate. Cobalt and manganese were separated utilizing tricaprylmethylammonium thiocyanate.