3158
Forecasting Graphite Recovery from Spent Lithium-Ion Batteries’
Black Mass with Particle-Based Separation Models
Lucas Pereira, Camila Guimarães da Silva Tochtrop, Kai Bachmann
Helmholtz-Zentrum Dresden-Rossendorf, Freiberg, Germany,
ERZLABOR Advanced Solutions GmbH, Freiberg, Germany
Alvaro José Rodríguez Medina, Martin Rudolph
Helmholtz-Zentrum Dresden-Rossendorf, Freiberg, Germany
Anna Vanderbruggen
Helmholtz-Zentrum Dresden-Rossendorf, Freiberg, Germany,
Université de Lorraine, GeoRessources, Nancy, France
ABSTRACT: The current increase in production of lithium-ion batteries claims for the development of
technologies for their later recycling. Flotation has been successfully used for recovering spherodized graphite
from the black mass of spent batteries. Forecasting flotation outcome from such a complex particle system
remains a challenge. Automated mineralogy has been used for characterizing battery recycling materials, but
the obtained data has so far only been partially used. Here, automated mineralogy and particle-based separation
models are used to compute the recovery of individual particles from a model black mass at flotation tests done
with different pulp solids content. Results indicate a 25% higher flotation rate constant for graphite particles at
lower solids content irrespective of particle size. Besides, evidence is presented for a distinct flotation mechanism
of LiCoO2 and LiNiMnCoO2 in comparison to metal foils and an SiO2 entrainment tracer added to the system.
INTRODUCTION
Recycling of spent lithium-ion batteries (LIBs) is substan-
tial to prevent the loss of substantial amounts of critical raw
materials to waste, especially considering the high amount
of these batteries expected to be utilized in the upcoming
decades due to the new energy system (IEA, 2021). Within
the raw materials used in LIBs, some present a supply risk,
such as Al, Cu, Ni, and Mn, while others are classified as a
critical raw material by the European Commission, such as
Co, Li and natural graphite (European Commission, 2020).
Despite graphite being one of the most important anode
materials and composing ca. 20% of a LIBs’ mass, most
recycling efforts are dedicated to recover the metal fractions
given their higher aggregated value. Graphite is thus often
lost to final waste streams or used as a reducing agent in
pyrometallurgy. Recently, many studies have investigated
the potential recovery of graphite from LIBs via froth flo-
tation. In this concentration exercise, the feed material is
typically the fine size fraction (100 µm) of the so-called
black mass—the shredding product of spent LIBs—that
contains both liberated active particles of cathode active
materials (CAMs) and graphite particles (Vanderbruggen
et al., 2021a).
Black mass flotation is supported by the contrast in
surface wettability between graphite and CAMs, respec-
tively of high and surface wettability. Yet, non-particulate
Forecasting Graphite Recovery from Spent Lithium-Ion Batteries’
Black Mass with Particle-Based Separation Models
Lucas Pereira, Camila Guimarães da Silva Tochtrop, Kai Bachmann
Helmholtz-Zentrum Dresden-Rossendorf, Freiberg, Germany,
ERZLABOR Advanced Solutions GmbH, Freiberg, Germany
Alvaro José Rodríguez Medina, Martin Rudolph
Helmholtz-Zentrum Dresden-Rossendorf, Freiberg, Germany
Anna Vanderbruggen
Helmholtz-Zentrum Dresden-Rossendorf, Freiberg, Germany,
Université de Lorraine, GeoRessources, Nancy, France
ABSTRACT: The current increase in production of lithium-ion batteries claims for the development of
technologies for their later recycling. Flotation has been successfully used for recovering spherodized graphite
from the black mass of spent batteries. Forecasting flotation outcome from such a complex particle system
remains a challenge. Automated mineralogy has been used for characterizing battery recycling materials, but
the obtained data has so far only been partially used. Here, automated mineralogy and particle-based separation
models are used to compute the recovery of individual particles from a model black mass at flotation tests done
with different pulp solids content. Results indicate a 25% higher flotation rate constant for graphite particles at
lower solids content irrespective of particle size. Besides, evidence is presented for a distinct flotation mechanism
of LiCoO2 and LiNiMnCoO2 in comparison to metal foils and an SiO2 entrainment tracer added to the system.
INTRODUCTION
Recycling of spent lithium-ion batteries (LIBs) is substan-
tial to prevent the loss of substantial amounts of critical raw
materials to waste, especially considering the high amount
of these batteries expected to be utilized in the upcoming
decades due to the new energy system (IEA, 2021). Within
the raw materials used in LIBs, some present a supply risk,
such as Al, Cu, Ni, and Mn, while others are classified as a
critical raw material by the European Commission, such as
Co, Li and natural graphite (European Commission, 2020).
Despite graphite being one of the most important anode
materials and composing ca. 20% of a LIBs’ mass, most
recycling efforts are dedicated to recover the metal fractions
given their higher aggregated value. Graphite is thus often
lost to final waste streams or used as a reducing agent in
pyrometallurgy. Recently, many studies have investigated
the potential recovery of graphite from LIBs via froth flo-
tation. In this concentration exercise, the feed material is
typically the fine size fraction (100 µm) of the so-called
black mass—the shredding product of spent LIBs—that
contains both liberated active particles of cathode active
materials (CAMs) and graphite particles (Vanderbruggen
et al., 2021a).
Black mass flotation is supported by the contrast in
surface wettability between graphite and CAMs, respec-
tively of high and surface wettability. Yet, non-particulate