Study of lithium separation, concentration and precipitation during the hydrometallurgical process of black mass.

Abstract

The need for efficient recovery of lithium through recycling of lithium-ion batteries has increased in recent time to meet the growing demand of li as well as to mitigate the supply risk of this critical resource. The supply of Li from primary sources is not enough to offset the growing demand which requires Li from secondary sources such as end-of-life lithium-ion batteries to feed and close the loop. The recovery of Ni, Co and Mn have become more established methods, however, the efficient recovery of Li is still lagging behind. In order to obtained a high enough recovery and purity of Li in the form of Li2CO3, this study evaluates the effect of chemical precipitation and CO2 precipitation. In the recovery of Ni, Co and Mn, NH3 in the form of NH4OH is often used in adjusting pH in order to precipitate these metals. This study which focuses on recovering Li from a downstream process of this stuff also focuses on the handling of NH3 that is still present in the Li recovery feed solution. Experimental results demonstrate that it is possible to achieve a Li recovery of 80% and a purity >96.5% through chemical precipitation, under optimised pH, temperature and CO32-:Li+ ratio. At a pH of 9.7, and operating temperature of 80℃, it is possible to reach these results and have a Na content of <0.2%. The results also show that CO2 precipitation of Li2CO3 is feasible with recoveries up to 39% and purity of 85%. The handling of NH3 in the solution is also feasible by scrubbing with water to regenerate NH4OH which can be used in the adjustment of pH in other upstream precipitation processes. This study also confirms the feasibility of having a closed-loop system for managing NH3 and Na impurities which exploring the recovery of Li from LIBs recycling streams.