Recovery of zinc and manganese from spent alkaline batteries by liquid–liquid extraction with Cyanex 272

A hydrometallurgical route based on the liquid–liquid extraction technique using Cyanex 272 as extractant is investigated for the selective separation of metal values, in particular, zinc and manganese from spent alkaline batteries. The recycling route consists of following steps: (1) cryogenic dismantling of the spent batteries, (2) pre-treatment of the internal material consisting of drying, grinding and screening steps in order to produce a dry homogeneous powder, (3) leaching of the powder with sulphuric acid and (4) metal separation by liquid–liquid extraction. Bench scale experiments have shown that zinc and manganese are easily separated (ΔpH1/2≈2.0) using 20% (v/v) Cyanex 272 dissolved in Escaid 110 at 50 °C. Therefore, the proposed route can treat residues from both zinc–carbon and alkaline batteries because metal composition of these batteries is quite similar. The metal content of other batteries such as Ni–Cd and nickel-metal hydride (NiMH) has been also determined in order to include them in future investigations.