Oxidative precipitation of manganese from battery waste
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Journal Title
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Volume Title
Kemian tekniikan korkeakoulu |
Master's thesis
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Authors
Date
2024-08-29
Department
Major/Subject
Sustainable Metals Processing
Mcode
CHEM3026
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
Language
en
Pages
93 + 6
Series
Abstract
As the number of electric vehicles has increased, the recycling of lithium-ion batteries has become an important process in promoting the circular economy. In hydrometallurgy, precious metals, such as cobalt, nickel, and lithium, have received wide attention, whereas manganese has been less studied. Recently, battery-grade manganese was added to the European Critical Raw Materials Act in 2023 to lessen the dependence on external supplies for this material. Therefore, this thesis presents an approach for the recovery of manganese from synthetic LIBs leaching solution by utilizing the SO2/O2 gas mixture. The application of this oxidizing mixture could enable a selective and low-cost removal of Mn. A range of parameters was examined, and the experiments were divided into two series to investigate the effect of high and low manganese concentrations (15.6 g/L and 4.5 g/L, respectively). The results of the study showed that 1) the kinetics was generally slow; 2) the parameters, namely SO2/O2 gas ratio, SO2/Mn molar ratio (and consequently, gas flowrates), addition of sodium persulfate, and Mn concentration affected the kinetics of Mn precipitation; 3) the redox from 900 to 950mV was where the oxidative precipitation took place; 4) under condition of 4% (v/v) SO2/O2 gas ratio, SO2/Mn ratio of 1.58, S2O8/Mn ratio of 1, pH of 3, and at 45°C, highest removal of Mn was obtained; 5) The kinetics of experiment drastically decreased when Mn concentration fell between 3900 and 4000 mg/L; and finally 6) the precipitates were amorphous and contained birnessite MnO2 (sigma-MnO2), and the co-precipitations of Co and Ni were ascribed to the adsorbing ability of MnO2. It should be noted that the pH of the solution was not constant due to manual pH adjustment, and it could have a significant impact on the kinetics of the precipitation.Description
Supervisor
Lundström, MariThesis advisor
Vänskä, JereBudhathoki, Roshan
Keywords
oxidative precipitation, SO2/O2, manganese, lithium-ion batteries, MnO2, PLS