A study on the correlation of mineralogical properties of Li-ion battery waste and the efficiency of separation processes

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Journal Title
Journal ISSN
Volume Title
Kemian tekniikan korkeakoulu | Master's thesis
Date
2022-10-18
Department
Major/Subject
Funtional Materials for Global Challenges
Mcode
CHEM3061
Degree programme
Master's Programme in Advanced Materials for Innovation and Sustainability
Language
en
Pages
60+15
Series
Abstract
It is now well established that the presence of organic compounds (PVDF binder and electrolyte) on the surface of cathode and anode materials impair their separation by flotation as their wettability difference is reduced. Aiming to remove these organic substances and liberate the electrode particles to get a better flotation efficiency, two conditioning methods were applied to black mass before flotation: mechanical attrition, i.e., milling for 1 min and 40 min, and thermal degradation i.e., pyrolysis at 500°C and 600°C. The evolution of morphology, composition, and liberation degree of black mass samples after pyrolysis and milling were investigated by SEM-EDS and TGA-MS. The EDS results demonstrated that pyrolysis decreased the F content coming from the PVDF binder from 33%w to 5–6%w, whereas milling only reduced it to 10–20%w. The SEM micrographs also display fewer presence of aggregates of cathode particles in pyrolyzed samples compared to milling samples. Other features observed by SEM that might impact black mass flotation are also discussed. Additionally, by TGA-MS the degradation stage corresponding to organic compounds revealed the existence of more organics and impurities in samples treated by milling (5–6%w) than in the pyrolyzed samples (2–3%w) demonstrating that pyrolysis achieves a better liberation in black mass samples prior to flotation.
Description
Supervisor
Serna Guerrero, Rodrigo
Thesis advisor
Rinne, Tommi
Keywords
lithium-ion batteries, black mass, froth flotation, liberation methods, characterization techniques, recycling
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Citation