Hydrometallurgical process for rare earth elements recovery from spent Ni-HM batteries

Rare earth elements (REE) have been widely used in various sectors, from the aerospace and steel industries, to electronic applications, particularly in displays and batteries for portable devices. The high demand for newer and better equipment has increased the consumption of the REE and at the same time the need for its recovery from electronic wastes. For that reason, recycling of batteries is important, principally the Ni-HM batteries, owing to their elevated content of rare earths elements. In the present work, electrodes from spent Ni-HM batteries were leached using H2SO4, in the presence of ozone as the oxidant, where recoveries of 96% for La, Ce and Nd were obtained at room temperature. The separation of Ni and Co from the leach solutions was performed using an electrochemical reactor, after which REE were precipitated, obtaining a mixture of its hydroxides with impurities below 1%, according to EDS analysis.