Hydrometallurgical process for recovery of metal values from spent lithium-ion secondary batteries

We report studies on the separation and recovery of metal values such as cobalt and lithium from spent lithium-ion secondary batteries. Effects of leachant concentration, temperature, reaction time and solid-to-liquid ratio on leaching of cobalt and lithium contained in the anode material of the batteries were examined using several reagents such as sulfurous acid, hydroxylamine hydrochloride and hydrochloric acid as leachants. Hydrochloric acid was found to be the most suitable leachant among the three reagents. A leaching efficiency of more than 99% of cobalt and lithium could be achieved when 4 M HCl solution was used at a temperature of 80 degrees C and a reaction time of 1 h. The pH of the final pregnant liquor obtained was around 0.6 and the concentrations of cobalt and lithium were approximately 17 and 1.7 (g l(-1)), respectively. The cobalt in the leach liquor was extracted selectively and nearly completely with 0.90 M PC-88A in kerosene at equilibrium pH approximate to 6.7 in a single stage at an O:A ratio of 0.85:1. Then the cobalt in the loaded organic phase was recovered as cobalt sulfate with high purity (Li/Co < 5 x 10(-5)) after lithium scrubbing with a dilute hydrochloric acid solution containing 30 g l(-1) of cobalt at an O:A phase ratio of 10:1, This was followed by stripping with a 2 M H2SO4 solution at an O:A ratio of 5:1. The raffinate was concentrated and the lithium remaining in the aqueous solution was readily recovered as lithium carbonate precipitate by the addition of a saturated sodium carbonate solution at close to 100 degrees C. The content of cobalt in the lithium precipitate was found to be less than 0.07%. Lithium recovery approached 80%. A flowsheet of the hydrometallurgical process for the recovery of cobalt and lithium from the spent lithium-ion secondary batteries has been established based on the experimental results. (C) 1998 Elsevier Science B.V.