A process has been developed in order to recover and recycle the metals present in spent batteries, including alkaline spent batteries alone or mixed with other types of spent batteries. This method shows a good potential in terms of metals recoveries efficiencies and
economic feasibility. Firstly, the spent batteries are crushed (optionally after having been frozen in the case of spent batteries of mixed types). Then, the undesirable parts (plastics, steel cases, papers, etc.) are removed by screening. The collected
powder, containing the metals, is mixed with a solution of
sulfuric acid in the presence of a
reducing agent. The
solid / liquid separation is carried out by
filtration and the
leachate is purified in order to selectively recover the metals. The purification steps consist of: a) recovering Zn by
solvent extraction followed by an
electrowinning process; b) simultaneously recovering Mn and Cd by
solvent extraction process; c) selectively recovering Cd from the mixture solution of Cd and Mn by
electrowinning process; d) precipitating Mn from a pure solution of MnSO4 in a
carbonate form; e) removing the impurities present in the
effluent by
solvent extraction in order to obtain a pure NiSO4 solution; f) precipitating Ni from a NiSO4 solution in a
carbonate form.