This work sought to study cadmium, cobalt and nickel recovery from Ni-Cd batteries applying hydrometallurgical techniques. Leaching experiments were carried out at 25ºC for a 1/10 solid/liquid ratio. It was shown that leaching kinetics is faster if an oxidant is applied: over 90% metals extraction could be achieved for 2mol/L and 0.5mol/L sulfuric and nitric acid respectively in 2 hours. Moreover the metals could be selectively separated by solvent extraction. It was studied the effect of pH on the extraction of the tree metals using two different extractants (D2EHPA and CYANEX 272). The experiments were carried out at 25oC for a phase ratio (A/O) of 1. It was observed that loadings of 90% cadmium, 10% cobalt and 0% nickel could be obtained for D2EHPA at pH 2.5. Besides, CYANEX 272 uptakes 95% cadmium, 95% cobalt and 5% nickel at pH 5.5. Consequently D2EHPA can be applied to separate cadmium from cobalt and nickel. Following nickel and cobalt can be selectively obtained using CYANEX 272. The process proposed can be successfully applied to recovery heavy metals from Ni-Cd batteries.
Ni-Cd batteries; leaching; solvent extraction; heavy metals
