37
The Importance of Process Mineralogy and Geometallurgy in
Enabling the Energy Transition
Megan Becker
Centre for Minerals Research, Department of Chemical Engineering, University of Cape Town, South Africa
ABSTRACT: Enabling the energy transition requires the mining industry to generate unprecedented
amounts of metals such as Li, Cu, Co, Ni, Mn, Zn and the REE. Dependent on metal concentrations, these
geochemically scarce metals may occur in discrete minerals, or substitute for other elements in more common
minerals subsequently forming complex, refractory ores. Our future ore sources will sample this mineralogical
variability from a variety of feedstocks including conventional primary ores and historical mine waste. Using
two case studies, this paper demonstrates the pivotal role of process mineralogy and geometallurgy in facilitating
the sustainable processing of these complex ores, thus ensuring a successful transition towards cleaner energy
sources. Case study examples cover the problem of Mn distribution in a zinc sulphide ore processed through
flotation, as well REE recovery through leaching from a weathered crust elution deposited ion adsorption
clay deposit.
INTRODUCTION
Enabling the energy transition requires the mining indus-
try to generate an unprecedented tonnage of metals such as
Li, Cu, Co, Ni, Mn, Zn and rare earth elements (REE) as
raw materials in the production of renewable energy (IEA,
2022). These metals are classified as critical because they
are essential components in renewable energy technology,
and naturally occur in very low crustal abundances lead-
ing to a potential supply risk (that is often compounded
by various geopolitical factors). Numerous authors have
investigated projections between the demand and sup-
ply of such metals (Figure 1) and emphasized the need to
process both conventional primary and secondary depos-
its (including waste rock, tailings and slags), as well as
the more non-conventional secondary deposits generated
through recycling to meet this demand (Rostek et al.,
2023). Understanding the deportment of these metals, and
the variability thereof, in these deposits is a key component
in being able to sustainably process these ores.
An excellent starting point in understanding the deport-
ment of metals is to first consider the earth’s endowment of
these metals. In his seminal paper in 1976, Skinner defined
geochemically abundant metals as those with a concentra-
tion greater than 0.1 wt.% in the earth’s crust, of which
only five metals meet this criterion – Al, Fe, Mg, Mn and Ti
(Skinner, 1976). All other metals are therefore considered
geochemically scarce, including the critical metals impor-
tant to the energy transition. It is only through a unique
set of geological processes that these geochemically scarce
metals are upgraded to form a mineral deposit—a natural
concentration of valuable metals in an accessible part of the
earth’s crust that can be profitably extracted. Appreciating
whether these metals are geochemically abundant or scarce
is important because it defines which mineralogical forms
the valuable metal occurs in.
Geochemically abundant metals occur as major con-
stituents in rock-forming minerals such as Fe in olivine
((Mg,Fe)2SiO4) or pyroxene ((Mg,Fe)2Si2O6). The relative
The Importance of Process Mineralogy and Geometallurgy in
Enabling the Energy Transition
Megan Becker
Centre for Minerals Research, Department of Chemical Engineering, University of Cape Town, South Africa
ABSTRACT: Enabling the energy transition requires the mining industry to generate unprecedented
amounts of metals such as Li, Cu, Co, Ni, Mn, Zn and the REE. Dependent on metal concentrations, these
geochemically scarce metals may occur in discrete minerals, or substitute for other elements in more common
minerals subsequently forming complex, refractory ores. Our future ore sources will sample this mineralogical
variability from a variety of feedstocks including conventional primary ores and historical mine waste. Using
two case studies, this paper demonstrates the pivotal role of process mineralogy and geometallurgy in facilitating
the sustainable processing of these complex ores, thus ensuring a successful transition towards cleaner energy
sources. Case study examples cover the problem of Mn distribution in a zinc sulphide ore processed through
flotation, as well REE recovery through leaching from a weathered crust elution deposited ion adsorption
clay deposit.
INTRODUCTION
Enabling the energy transition requires the mining indus-
try to generate an unprecedented tonnage of metals such as
Li, Cu, Co, Ni, Mn, Zn and rare earth elements (REE) as
raw materials in the production of renewable energy (IEA,
2022). These metals are classified as critical because they
are essential components in renewable energy technology,
and naturally occur in very low crustal abundances lead-
ing to a potential supply risk (that is often compounded
by various geopolitical factors). Numerous authors have
investigated projections between the demand and sup-
ply of such metals (Figure 1) and emphasized the need to
process both conventional primary and secondary depos-
its (including waste rock, tailings and slags), as well as
the more non-conventional secondary deposits generated
through recycling to meet this demand (Rostek et al.,
2023). Understanding the deportment of these metals, and
the variability thereof, in these deposits is a key component
in being able to sustainably process these ores.
An excellent starting point in understanding the deport-
ment of metals is to first consider the earth’s endowment of
these metals. In his seminal paper in 1976, Skinner defined
geochemically abundant metals as those with a concentra-
tion greater than 0.1 wt.% in the earth’s crust, of which
only five metals meet this criterion – Al, Fe, Mg, Mn and Ti
(Skinner, 1976). All other metals are therefore considered
geochemically scarce, including the critical metals impor-
tant to the energy transition. It is only through a unique
set of geological processes that these geochemically scarce
metals are upgraded to form a mineral deposit—a natural
concentration of valuable metals in an accessible part of the
earth’s crust that can be profitably extracted. Appreciating
whether these metals are geochemically abundant or scarce
is important because it defines which mineralogical forms
the valuable metal occurs in.
Geochemically abundant metals occur as major con-
stituents in rock-forming minerals such as Fe in olivine
((Mg,Fe)2SiO4) or pyroxene ((Mg,Fe)2Si2O6). The relative