Metal Recovery from Nickel Metal Hydride Batteries Using Cyanex 923 in Tricaprylylmethylammonium Nitrate from Chloride Aqueous Media

Abstract

A flow sheet has been developed for recovery of metals from nickel metal hydride batteries using the neutral extractant Cyanex 923 dissolved in the ionic liquid tricaprylylmethylammonium nitrate, [A336][NO3], and a synthetic chloride-based aqueous leach solution. The process allows purification of nickel in a single step by extracting chloride and nitrate complexes of the extractable transition metals and rare earths. Three selective strip operations utilizing first nitrate, stripping cobalt and manganese, and then chloride complexation, stripping the rare earths, followed by stripping of iron and zinc. Cobalt in the nitrate strip solution was separated from manganese by extraction with the ionic liquid tricaprylylmethylammonium thiocyanate, [A336][SCN].