1278
Processing of a Phosphate Flotation Tails for Recovery of
Rare Earths and Phosphate
Haijun Liang, Patrick Zhang, Zhen Jin, Aaron Medley
FIPR Institute, Florida Polytechnic University
David DePaoli
Oak Ridge National Laboratory
ABSTRACT: Phosphorite, or phosphate rock, has been attracting more attention in recent years for its potential
as a promising unconventional resource for rare earth elements (REEs). This paper presents a processing scheme
for recovering both REEs and phosphate values from an amine flotation tails of phosphate beneficiation in
Florida. The REEs in the tails exist manly as monazite and xenotime associated with some heavy minerals.
The processing flowsheet includes gravitation separation to pre-concentrate REE-containing and phosphate
minerals, flotation of the gravity separation concentrate to further upgrade REEs and phosphates, and sulfuric
acid leaching to recover REE and phosphate from the final concentrate.
Gravity separation using a shaking table upgraded the total REEs content from about 202 ppm to 657 ppm
with a concentrate yield of 12.51%, REEs recovery of about 41%, and P2O5 recovery of 33%. Fatty acid flota-
tion of the shaking table concentrate produced a concentrate containing 1106 ppm REEs and 14.90% P2O5
at REE recovery of about 86% and P2O5 recovery of 90%, respectively. Tests of concentrated sulfuric acid
pyrolysis – water leaching were conducted on flotation concentrate, and achieved recoveries of about 85% for
REE and 93% for P2O5. Although the REEs minerals and apatite can be concentrated and leached through the
process in this paper, the existence states of most of the valuable minerals as fine grains interlocking with gangue
minerals are the main obstacle for further improving the separation and extraction efficiency.
Keywords: Rare earths Phosphate flotation leaching gravity separation
INTRODUCTION
Phosphorite, or phosphate rock, has been used as a feed-
stock for producing phosphate fertilizer for more than 150
years. In the modern manufacturing process, phosphate
rock is produced through beneficiating phosphate ore by
removing large amounts of wastes including phosphatic
clay and flotation tails. Then the phosphate concentrate
(rock) undergoes a so called wet-process to be digested by
mineral acid to produce phosphoric acid, and generate two
waste by-products of phosphogypsum and phosphoric acid
sludge. Finally, phosphoric acid is converted into various
phosphate fertilizers [Becker, 1983].
In recent years phosphorite is attracting attention again
for its potential as an unconventional resource for REEs
[Pan and Macrae, 1993 Schonevelde et al., 2015 Zhang,
2014]. Estimation by Kanazawa [Kanazawa and Kamirani,
2006] revealed that there are about 50,000,000 tons of rare
earths stored in phosphate resources around the world.
Processing of a Phosphate Flotation Tails for Recovery of
Rare Earths and Phosphate
Haijun Liang, Patrick Zhang, Zhen Jin, Aaron Medley
FIPR Institute, Florida Polytechnic University
David DePaoli
Oak Ridge National Laboratory
ABSTRACT: Phosphorite, or phosphate rock, has been attracting more attention in recent years for its potential
as a promising unconventional resource for rare earth elements (REEs). This paper presents a processing scheme
for recovering both REEs and phosphate values from an amine flotation tails of phosphate beneficiation in
Florida. The REEs in the tails exist manly as monazite and xenotime associated with some heavy minerals.
The processing flowsheet includes gravitation separation to pre-concentrate REE-containing and phosphate
minerals, flotation of the gravity separation concentrate to further upgrade REEs and phosphates, and sulfuric
acid leaching to recover REE and phosphate from the final concentrate.
Gravity separation using a shaking table upgraded the total REEs content from about 202 ppm to 657 ppm
with a concentrate yield of 12.51%, REEs recovery of about 41%, and P2O5 recovery of 33%. Fatty acid flota-
tion of the shaking table concentrate produced a concentrate containing 1106 ppm REEs and 14.90% P2O5
at REE recovery of about 86% and P2O5 recovery of 90%, respectively. Tests of concentrated sulfuric acid
pyrolysis – water leaching were conducted on flotation concentrate, and achieved recoveries of about 85% for
REE and 93% for P2O5. Although the REEs minerals and apatite can be concentrated and leached through the
process in this paper, the existence states of most of the valuable minerals as fine grains interlocking with gangue
minerals are the main obstacle for further improving the separation and extraction efficiency.
Keywords: Rare earths Phosphate flotation leaching gravity separation
INTRODUCTION
Phosphorite, or phosphate rock, has been used as a feed-
stock for producing phosphate fertilizer for more than 150
years. In the modern manufacturing process, phosphate
rock is produced through beneficiating phosphate ore by
removing large amounts of wastes including phosphatic
clay and flotation tails. Then the phosphate concentrate
(rock) undergoes a so called wet-process to be digested by
mineral acid to produce phosphoric acid, and generate two
waste by-products of phosphogypsum and phosphoric acid
sludge. Finally, phosphoric acid is converted into various
phosphate fertilizers [Becker, 1983].
In recent years phosphorite is attracting attention again
for its potential as an unconventional resource for REEs
[Pan and Macrae, 1993 Schonevelde et al., 2015 Zhang,
2014]. Estimation by Kanazawa [Kanazawa and Kamirani,
2006] revealed that there are about 50,000,000 tons of rare
earths stored in phosphate resources around the world.