Close loop separation process for the recovery of Co, Cu, Mn, Fe and Li from spent lithium-ion batteries

摘要

Lithium-ion batteries (LIBs) are essential energy source used in advanced electronic gadgets for getting constant and continuous power supply. Huge amount of spent LIBs are generated after their end use. LIBs contain metals, organics and plastics which require proper treatment before disposal. Keeping in view of stringent environmental regulations, limited natural resources and energy crisis, adopting recycling will not only protect the environment and pacify the gap between demand and supply but also conserve the natural resources. Present paper reports a complete process for the recycling of LIBs to recover metals and materials as value added products fulfilling zero waste concept. Initially, the spent LIBs were crushed and beneficiated by wet scrubbing process to separate cathodic material, plastic and metallic fractions. The cathodic material contained 20% Co and 2.4% Li along with other impurities (Mn, Fe, Cu). The cathodic material obtained from different LIBs were homogenized and put to leaching studies to optimize various process parameters viz. effect of leachant concentration, temperature, time, etc. About 97% Co and 99.99% Li were leached using 2 M H2SO4 and 10% H2O2 at room temperature, in 2 h maintaining pulp density 75 g/L. Kinetics for leaching of Co fitted well with Chemical reaction control dense constant size cylindrical particles model, i.e. 1 - (1 - X)(1/2) = Kct. The leach liquor obtained was further processed to recover Mn and Fe using (NH4)(2)S2O8 as a precipitant whereas 99.99% Cu was extracted using LIX 84 IC at eq. pH 2, O/A ratio 1/1 and mixing time 5 min. Further, from the leach liquor depleted with Mn, Fe and Cu, similar to 98% Co was extracted using 20% Cyanex 272 at pH 4.8 in 10 min maintaining phase ratio (O/A) 1/1 in two stages, leaving Li in the raffinate. From the pure Co solution, value added products as metal and salt were produced using electrowinning/evaporation/precipitation techniques. The TCLP test of leached residue shows the presence of metals within permissible limit and the effluent generated was treated in an effluent treatment plant (ETP) with standard procedure and recycled to the system. The developed clean process is economical as well as environment friendly and has potential to be translated in industry after scale-up studies.