1192 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
mineralogy and due to the fact that it currently relies exclu-
sively on gravity separation for ongoing commercial produc-
tion (Rainbow Rare Earths, 2024). This deposit is uniquely
high grade with an anticipated ROM range of 47% to 67%
REO per the current exploration target. Thus, compared to
most deposits, minimal upgrading is necessary to achieve
the offtake terms of 55% REO or greater. The REE miner-
alogy consists of predominantly bastnaesite and monazite,
while the gangue consists mainly of barite and mica. Unlike
Mountain Pass, the Gakara material is virtually devoid of
calcite and dolomite despite its carbonatite mineralization.
A simplified version of the proposed Gakara flowsheet is
shown in Figure 4 (Rainbow Rare Earths, 2024).
For the lower end of these REE feed grades, the com-
bined jig and shaking table recovery is estimated to be 83%,
while for the higher grade feeds it is also higher at 92%.
The tailings themselves are noteworthy in as much as they
are estimated to contain grades of up to 38% REO, which
would still exceed the grades of existing exploited deposits.
As a result, the tailings are intended to be stockpiled for
potential future retreatment.
MONAZITE BENEFICIATION
Monazite is a rare earth phosphate mineral that can contain
varying amounts of thorium. Its general formula is (Ce, La,
Th, Ca) (PO4, SiO4, SO4). Originally, monazite was the
primary source of rare earths as a byproduct of the produc-
tion of thorium (Salatic, 1967). Thorium has been viewed
as a possible fuel for nuclear reactors. But the decreasing
interest in thorium due to environmental concerns shifted
the importance of monazite towards the extraction of rare
earth elements and compounds from other minerals and
metallurgical processes. (Barghusen, 1957, Zhu, et al.
2015).
Monazite has relatively high specific gravity (4.9 – 5.5),
its nonconductive, weakly magnetic and has a hardness of
5 – 5.5. Its crystal structure is monoclinic with a =6.7902,
b =7.0203, c =6.4674. The crystal structure can also be
metamict because of radiation damage to the lattice.
Monazite may contain up to 70% of mostly light rare
earth elements (La – Eu) (Jordens, et al., 2012), 4–12%
thorium and a small amount of uranium. The rare earth ele-
ments distribution in monazite varies from one deposit to
another as illustrated in Table 2 (Gupta and Krishnamurthy,
2005).
As previously mentioned, monazite is the second most
important source of rare earth after bastnaesite. The two
minerals together with along with some minor amounts of
xenotime minerals have been the only successful commer-
cial sources of rare earth element production. Combined.
they constitute 95% of rare earth resources in the world
(Lay, 2021). Monazite occurs in igneous rocks, metamor-
phic rocks, vein deposits. The most important sources are
beach placers where together with cassiterite, gold, ilmen-
ite, magnetite, rutile, scheelite, and zircon the heavy min-
eral group is formed. Monazite placer deposits are found
in the United States (Florida, Georgia, Idaho, North and
South Carolina, Tennessee), Argentina, Australia, Brazil,
Figure 3. Bayan Obo simplified process flowsheet
mineralogy and due to the fact that it currently relies exclu-
sively on gravity separation for ongoing commercial produc-
tion (Rainbow Rare Earths, 2024). This deposit is uniquely
high grade with an anticipated ROM range of 47% to 67%
REO per the current exploration target. Thus, compared to
most deposits, minimal upgrading is necessary to achieve
the offtake terms of 55% REO or greater. The REE miner-
alogy consists of predominantly bastnaesite and monazite,
while the gangue consists mainly of barite and mica. Unlike
Mountain Pass, the Gakara material is virtually devoid of
calcite and dolomite despite its carbonatite mineralization.
A simplified version of the proposed Gakara flowsheet is
shown in Figure 4 (Rainbow Rare Earths, 2024).
For the lower end of these REE feed grades, the com-
bined jig and shaking table recovery is estimated to be 83%,
while for the higher grade feeds it is also higher at 92%.
The tailings themselves are noteworthy in as much as they
are estimated to contain grades of up to 38% REO, which
would still exceed the grades of existing exploited deposits.
As a result, the tailings are intended to be stockpiled for
potential future retreatment.
MONAZITE BENEFICIATION
Monazite is a rare earth phosphate mineral that can contain
varying amounts of thorium. Its general formula is (Ce, La,
Th, Ca) (PO4, SiO4, SO4). Originally, monazite was the
primary source of rare earths as a byproduct of the produc-
tion of thorium (Salatic, 1967). Thorium has been viewed
as a possible fuel for nuclear reactors. But the decreasing
interest in thorium due to environmental concerns shifted
the importance of monazite towards the extraction of rare
earth elements and compounds from other minerals and
metallurgical processes. (Barghusen, 1957, Zhu, et al.
2015).
Monazite has relatively high specific gravity (4.9 – 5.5),
its nonconductive, weakly magnetic and has a hardness of
5 – 5.5. Its crystal structure is monoclinic with a =6.7902,
b =7.0203, c =6.4674. The crystal structure can also be
metamict because of radiation damage to the lattice.
Monazite may contain up to 70% of mostly light rare
earth elements (La – Eu) (Jordens, et al., 2012), 4–12%
thorium and a small amount of uranium. The rare earth ele-
ments distribution in monazite varies from one deposit to
another as illustrated in Table 2 (Gupta and Krishnamurthy,
2005).
As previously mentioned, monazite is the second most
important source of rare earth after bastnaesite. The two
minerals together with along with some minor amounts of
xenotime minerals have been the only successful commer-
cial sources of rare earth element production. Combined.
they constitute 95% of rare earth resources in the world
(Lay, 2021). Monazite occurs in igneous rocks, metamor-
phic rocks, vein deposits. The most important sources are
beach placers where together with cassiterite, gold, ilmen-
ite, magnetite, rutile, scheelite, and zircon the heavy min-
eral group is formed. Monazite placer deposits are found
in the United States (Florida, Georgia, Idaho, North and
South Carolina, Tennessee), Argentina, Australia, Brazil,
Figure 3. Bayan Obo simplified process flowsheet