Recovery of zinc and manganese from “black mass” of waste Zn-MnO2 alkaline batteries by solvent extraction technique with ionic liquids, DESs and organophosphorous-based acids

Abstract

Solvent extraction was used to recover zinc and manganese from the “black mass” (BM) produced in the zinc plant in Poland, the secondary waste from spent zinc-batteries. A lot of methods and extracting solvents such as ionic liquids (ILs), organophosphorous-based acids and Deep Eutectic Solvents (DESs) were investigated. The environmentally friendly method of metal ions extraction without the primary process of waste batteries leaching with sulfuric acid has been proposed. The BM solvent extraction with trihexyltetradecylphosphonium chloride ([P6,6,6,14][Cl], Cyphos IL 101), trihexyltetradecylphosphonium thiocyanate ([P6,6,6,14][SCN]), bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272), and bis-(2-ethylhexyl) phosphoric acid (D2EHPA) has been presented. Process factors and organic to water ratios were studied. A flowchart for zinc and manganese recovery from BM has been presented. The 100 wt% extraction efficiency for Zn(II) was obtained with (Cyanex 272 + diethyl phosphite).Quick and efficient extraction, with 100 wt% recovery of zinc and manganese, was obtained using DES (choline chloride [N2OH,1,1,1][Cl] : lactic acid 1:2, as well as choline chloride [N2OH,1,1,1][Cl] : malonic acid 1:1) with the addition of didecyldimethylammonium chloride surfactant, DDACl. Moreover, the recovery of zinc in the form of a metal deposit was carried out using a potential-control electrolysis from acidic aqueous solutions obtained after extraction with organophosphorous-based acids and diethyl phosphite. For all the systems, the selectivity and distribution ratios have been presented.