Selective recovery and intensification of Mn from spent LiMn2O4 using sulfuric acid as lixiviant and Na-D2EHPA as extractant

Abstract

ABSTRACT Despite the rising demand for lithium-ion batteries and their widespread acceptance, recycling and repurposing end-of-life lithium-ion battery materials is still a work in progress. This will help mitigate the dependence on raw materials and risks of shortage while promoting a circular economy. The present work addresses a hydrometallurgical process to recover Mn from spent LiMn2O4 using sulphuric acid as a lixiviant and Na-D2EHPA as extractant. Effects of various leaching parameters have been studied and the pregnant leach solution has been generated using 1 mol/L H2SO4 with 6% H2O2 at a pulp density of 10 g/L, maintaining the temperature at 30°C at 450 rpm for 1 hour which contained 2.52 g/L Mn and 0.545 g/L of Li. The PLS was subjected to separation using solvent extraction method taking 70% saponified di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractant. The McCabe-Thiele plot suggested two theoretical stages at O:A ratio of 1:1 using 0.3 mol/L Na-D2EHPA with 99.94% extraction of Mn and 10.2% co-extraction of Li. The co-extracted lithium was removed by scrubbing with MnSO4 solution. The loaded organic containing 2.574 g/L Mn was stripped using 10% H2SO4 at two stages at O: A ratio of 1.5:1 and enriched the concentration of manganese 1.5 times in the stripped solution.