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. Effe cts 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 a s sulfurous acid, hydroxylamine hydrochloride and hydrochloric acid as leachants. Hydrochloric acid was found to be the most suitable leacha nt 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 a t 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 concentratio ns of cobalt and lithium were approximately 17 and 1.7 (g l(-1)), resp ectively. The cobalt in the leach liquor was extracted selectively and nearly completely with 0.90 M PC-88A in kerosene at equilibrium pH ap proximate 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 wi th high purity (Li/Co < 5 x 10(-5)) after lithium scrubbing with a dil ute 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 H2SO 4 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 c arbonate solution at close to 100 degrees C. The content of cobalt in the lithium precipitate was found to be less than 0.07%. Lithium recov ery approached 80%. A flowsheet of the hydrometallurgical process for the recovery of cobalt and lithium from the spent lithium-ion secondar y batteries has been established based on the experimental results. (C ) 1998 Elsevier Science B.V.