Hydrometallurgical recovery of critical metals from NMC 523 powders and its associated environmental impacts
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Authors
Solorio, Hector
Issue Date
2021
Type
Thesis
Language
Keywords
LCA , Leaching , Lithium , NMC , Optimization , Recycling
Alternative Title
Abstract
The lithium-ion battery industry’s accelerated growth is raising interest in the recycling of valuable metals. Lithium, manganese, cobalt, and nickel can be recovered from the cathode powders using inorganic acids like hydrochloric acid (HCl), nitric acid (HNO3), and sulfuric acid (H2SO4) in the leaching process. The experiments were designed using a statistical tool to optimize the parameters involved in the leaching process such as temperature, leaching time, concentration of leaching agents, solid to liquid ratio, and %volume of H2O2 to yield the best results for lithium recovery (%), nickel recovery (%), cobalt recovery (%) and manganese recovery (%). This study provides optimized leaching parameters, a detailed environmental impact assessment to identify the best inorganic acid in each category as well as the component contribution for each inorganic acid in all the categories included in the life cycle assessment (LCA) study, and a comparison of co-additives using the optimal conditions of the best performing leaching agent. The optimal conditions for each acid were H2SO4: 1.97 M, 69.99ºC, 20 min, L/S:0.091, and 0.957 H2O2 conc. (v/v%), HCl: 1.611 M, 69.99ºC, 89.9 min, L/S:0.098, and 0.99 %H2O2 conc (v/v%), and HNO3: 0.62 M, 58.2ºC, 58.7 min, L/S:0.097 and 0.66 H2O2 conc. (v/v%). After analyzing the environmental performance for each acid, it was found that depending on the impact category, each acid has more emissions than the others. Overall, H2SO4 showed the best environmental and operational performance among all inorganic acids to recover critical materials from NMC 523 cathode powders.