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A New Paradigm for the Recovery of Rare Earth Elements:
The High Activity Flowsheet as Applied to the Elk Creek Deposit
Tommee Larochelle, Eric Larochelle, Nour Dissem
L3 Process Development
Rick Sixberry, Scott Honan
Niocorp Developments Ltd.
ABSTRACT: The recovery of rare earth elements from ore typically involves acid leaching followed by step
neutralizations to remove impurities and control the solvent extraction process. The neutralization step used for
aluminum removal is highly detrimental to the recovery of scandium. L3 Process Development designed a novel
extraction process using its “scrum” approach to process development and proceeded through the bench scale,
pilot scale and demonstration scale test work on Niocorp’s Elk Creek project. This paper presents the highlight
of the scandium and REE recovery portion of the flowsheet, a radically new approach to REE recovery.
INTRODUCTION
NioCorp Developments Ltd. (NioCorp) is developing a
polymetallic technology metals extraction project centered
around niobium, titanium, scandium and magnet rare
earth elements (REE). These elements are all involved in
the technological substrate of the modern world and are in
short supply with regards to a global transition toward sus-
tainability. Furthermore, many of the products of the Elk
Creek deposit are critical to America’s national sovereignty
and to its defense.
The Elk Creek deposit, is an underground carbonatite
deposit with no surface outcrop. The primary minerals of
interest are the pyrochlore and rutile for niobium, a combi-
nation of rutile and ilmenite for titanium and a combina-
tion of bastnaesite, monazite, and synchysite for scandium
and the REE.
A Process for the extraction of these metals was devel-
oped by the authors in collaboration with SGS Mineral
Services and a NI 43-101 compliant feasibility study was
issued in 2017. In 2021, NioCorp mandated L3 Process
Development (L3) with the development of a novel flow-
sheet aimed at minimizing the capital and operating cost of
the previously developed process while adding magnet rare
earth elements to the project product suite. Between 2021
and 2023, L3 applied it’s scrum approach to process devel-
opment to the NioCorp project. The result of the effort was
a high activity process where no acid neutralization is used
in the core process operation. This high activity approach
allows for very high lixiviation rates of most metals, with
the exception of titanium and niobium which are concen-
trated in the leach residue. While the previous iteration of
the process resulted in approximately 60% scandium leach-
ing in the hydrochloric acid step (Verbaan et al., 2016), this
current version results in greater than 92% overall scan-
dium recovery. The main difference between the circuit is
that the acidity of the HCl leach solution in the current
process is significantly higher than in the previous itera-
tion owing the removal of calcium and magnesium in an
ammonium chloride leach step prior to the hydrochloric
acid leach stage.
A New Paradigm for the Recovery of Rare Earth Elements:
The High Activity Flowsheet as Applied to the Elk Creek Deposit
Tommee Larochelle, Eric Larochelle, Nour Dissem
L3 Process Development
Rick Sixberry, Scott Honan
Niocorp Developments Ltd.
ABSTRACT: The recovery of rare earth elements from ore typically involves acid leaching followed by step
neutralizations to remove impurities and control the solvent extraction process. The neutralization step used for
aluminum removal is highly detrimental to the recovery of scandium. L3 Process Development designed a novel
extraction process using its “scrum” approach to process development and proceeded through the bench scale,
pilot scale and demonstration scale test work on Niocorp’s Elk Creek project. This paper presents the highlight
of the scandium and REE recovery portion of the flowsheet, a radically new approach to REE recovery.
INTRODUCTION
NioCorp Developments Ltd. (NioCorp) is developing a
polymetallic technology metals extraction project centered
around niobium, titanium, scandium and magnet rare
earth elements (REE). These elements are all involved in
the technological substrate of the modern world and are in
short supply with regards to a global transition toward sus-
tainability. Furthermore, many of the products of the Elk
Creek deposit are critical to America’s national sovereignty
and to its defense.
The Elk Creek deposit, is an underground carbonatite
deposit with no surface outcrop. The primary minerals of
interest are the pyrochlore and rutile for niobium, a combi-
nation of rutile and ilmenite for titanium and a combina-
tion of bastnaesite, monazite, and synchysite for scandium
and the REE.
A Process for the extraction of these metals was devel-
oped by the authors in collaboration with SGS Mineral
Services and a NI 43-101 compliant feasibility study was
issued in 2017. In 2021, NioCorp mandated L3 Process
Development (L3) with the development of a novel flow-
sheet aimed at minimizing the capital and operating cost of
the previously developed process while adding magnet rare
earth elements to the project product suite. Between 2021
and 2023, L3 applied it’s scrum approach to process devel-
opment to the NioCorp project. The result of the effort was
a high activity process where no acid neutralization is used
in the core process operation. This high activity approach
allows for very high lixiviation rates of most metals, with
the exception of titanium and niobium which are concen-
trated in the leach residue. While the previous iteration of
the process resulted in approximately 60% scandium leach-
ing in the hydrochloric acid step (Verbaan et al., 2016), this
current version results in greater than 92% overall scan-
dium recovery. The main difference between the circuit is
that the acidity of the HCl leach solution in the current
process is significantly higher than in the previous itera-
tion owing the removal of calcium and magnesium in an
ammonium chloride leach step prior to the hydrochloric
acid leach stage.