From Lab Scale to Upscale Lithium Recovery Through Neutral Leaching of Black Mass

In the next ten years, it is expected that the electric vehicles market will grow at least 20 % each year. Therefore, the manufacturing and usage of batteries, mostly of Lithium ion batteries, will rise. To avoid shortages in supply, the recycling of end-of-life batteries is the key for a complete circular economy. However, the recovery of lithium from the active material—so called black mass (BM)—lacks in a consolidated recycling route, especially concerning industrial scale. In hydrometallurgical treatment, water leaching with CO2 injection was developed to recover Li in an early stage based on solubility, which is an easy and low cost operation. With that in mind, this work aims on upscaling neutral leaching of BM from lab scale in terms of Li recovery efficiency. Firstly, lab scale trials were performed in a 1.5 L reactor, CO2 bubbling of 6 L/min, 60 min of leaching time, constant stirring rate of 350 rpm, and particle size < 63 µm. The parameters that varied were temperature (20 °C and 80 °C) and solid/liquid ratio (10 g/L and 70 g/L). Based on these results, the upscaling leaching was performed in a 100 L reactor, but with an intermediate solid/liquid ratio of 30 g/L. The lab scale Li recovery efficiency achieved up to 80 % in the conditions of 10 g/L and 80 °C, however at 10 g/L and 20 °C the recovery efficiency was only 3 % lower. The compounds that are expected to be formed are Li2CO3 as well as LiHCO3, which are soluble in water under such conditions. In contract, when 70 g/L was tested, the results in both temperatures showed Li recovery efficiency of only around 50 % because the solubility limit is reached. In addition, in all scenarios, less than 1 mg/L of other metals was found in solution. Maintaining lower consumption of energy by using 20 °C in the upscale and a slight higher S/L ratio of 30 g/L to better simulate industrial conditions, the Li recovery efficiency showed nearly 65 %, which clearly indicates that S/L ratio is the key factor. In summary, an early stage Li recovery with water and CO2 injection in upscale presents low cost and has potential to be further enhanced. The Li2CO3 in solution can be precipitated through evaporation with low grade of impurities, which is beneficial for the refinement of the raw material for new batteries. Moreover, the filter cake after leaching contains Ni, Co, Mn, and Al. which can be further treated in hydrometallurgy, or even pyrometallurgically as an alloy.