1190 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
allows two or more bonds to form between a ligand and a
separate metal ion (Assis, et al., 1996). Four new collectors
have proven to be selective to bastnaesite in recent stud-
ies using micro flotation and bench scale flotation (Everly,
2018, Everly, et al., 2012).
Although collectors are the primary reagents used in
flotation, there are others which are used to enhance selec-
tivity. Some other reagent types include depressants, pH
modifiers and frothers. Depressants are used as an aid in a
flotation separation by selectively coating a gangue or tar-
get mineral surface, inhibiting the adsorption of the collec-
tor onto that mineral surface. Lignin sulphonate is used in
the flotation of bastnaesite to depress barite. Common pH
modifiers are potassium hydroxide and soda ash. Soda ash
has a dual purpose, as a pH modifier and a depressant or
dispersant, because it is a potential determining ion, which
makes the flotation of bastnaesite more effective at a spe-
cific pH.
Gravity Separation
Gravity separation is a technique involving the manipula-
tion of particle densities to separate the less dense particles
from the denser ones. A recent study used the ultrafine
Falcon centrifugal concentrator as gravity concentrator.
This allows effective separation to occur even with reduced
particle size s( Norgren, 2018) In related research efforts,
it was determined that, using gravity separation, the REE
bearing minerals can be effectively separated from calcite
and dolomite (Schriner, 2015, Schriner &Anderson, 2015,
Norgren, 2018, Norgren &Anderson, 2021, Norgren &
Anderson, 2021).
The Gakara deposit in Burundi is noteworthy for
a number of reasons, the most relevant of which are its
Figure 1. The Mountain Pass flotation flow sheet
allows two or more bonds to form between a ligand and a
separate metal ion (Assis, et al., 1996). Four new collectors
have proven to be selective to bastnaesite in recent stud-
ies using micro flotation and bench scale flotation (Everly,
2018, Everly, et al., 2012).
Although collectors are the primary reagents used in
flotation, there are others which are used to enhance selec-
tivity. Some other reagent types include depressants, pH
modifiers and frothers. Depressants are used as an aid in a
flotation separation by selectively coating a gangue or tar-
get mineral surface, inhibiting the adsorption of the collec-
tor onto that mineral surface. Lignin sulphonate is used in
the flotation of bastnaesite to depress barite. Common pH
modifiers are potassium hydroxide and soda ash. Soda ash
has a dual purpose, as a pH modifier and a depressant or
dispersant, because it is a potential determining ion, which
makes the flotation of bastnaesite more effective at a spe-
cific pH.
Gravity Separation
Gravity separation is a technique involving the manipula-
tion of particle densities to separate the less dense particles
from the denser ones. A recent study used the ultrafine
Falcon centrifugal concentrator as gravity concentrator.
This allows effective separation to occur even with reduced
particle size s( Norgren, 2018) In related research efforts,
it was determined that, using gravity separation, the REE
bearing minerals can be effectively separated from calcite
and dolomite (Schriner, 2015, Schriner &Anderson, 2015,
Norgren, 2018, Norgren &Anderson, 2021, Norgren &
Anderson, 2021).
The Gakara deposit in Burundi is noteworthy for
a number of reasons, the most relevant of which are its
Figure 1. The Mountain Pass flotation flow sheet