1280 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
2REPO4 +3H2SO4 =RE2(SO4)3 +2H3PO4 (1)
Ca5 (PO4)3 F +5H2SO4 =5CaSO4 +3H3PO4 +HF↑ (2)
where RE denotes element of rare earths.
RESULTS AND DISCUSSION
Pre-Concentration with Shaking Table
A representative sample of amine flotation tails was col-
lected from beneficiation plant at the Four Corner Mine,
one of the phosphate mines in central Florida. A represen-
tative sample of the tails was assayed for main components
and REE content, Table 1.
Quantitative mineral analysis was conducted using a
Mineral Liberation Analyzer (MLA). Two rare earth miner-
als were identified by MLA, they are monazite and xeno-
time, both at very low concentrations. Major non rare earth
minerals include quartz, fluorapatite, feldspar, zircon, and
rutile, Table 2.
The size range of the mineral particles was also analyzed
using MLA, Table 3.
A shaking table was used to concentrate the REEs-
bearing minerals and apatite from the amine flotation tail-
ings. The operating conditions of the shaking table were
optimized first and determined as follows:
• Transverse angle: 5°
• Stroke length: 7 mm
• Stroke frequency: 310 revolutions per minute
• Wash water: 3.5 gallons per minute
• Tailings feed: 583 grams per minute
Then 500 kilograms of the sample was used in shaking table
concentration, and the separation results are presented in
Table 4.
The pre-concentration removed up to 87.49 wt% of
solid from the feed and produced a concentrate with much
higher contents of REEs and P2O5 than those in the tail-
ings, but the recoveries of these two components were only
40.73% and 33.12%, respectively. It can be deduced from
the results that most of the valuable minerals in the amine
flotation tails existed in fine mineral particles interlocking
Table 1. Main chemical components in amine tails sample
Component Total REEs, ppm P2O5, %CaO, %Fe2O3, %MgO, %Al2O3, %
Content 201.96 3.01 5.62 0.29 0.02 0.28
Table 2. Quantitative mineral analysis of amine tails using MLA [Zhang et al., 2023]
Mineral Wt%% Mineral Wt%% Mineral Wt%%
Monazite 0.053 Tourmaline 0.353 Pseudo-rutile 1.125
Xenotime 0.003 Garnet 0.477 Rutile 0.450
Zircon 0.614 Epidote 0.119 Leucoxene 0.148
Apatite 8.703 Kyanite 1.174 Sphene 0.337
Wavellite 0.512 Staurolite 0.329 Limonite 0.016
Woodhouseite 0.009 Kaolin 0.048 Siderite 0.143
Quartz 80.011 Pyrite 0.047 Zinc spinel 0.003
Feldspar 5.294 Sphalerite 0.009 Others 0.003
Biotite 0.004 Calcite 0.003 Total 100.000
Table 3. Size distribution analysis for the major valuable minerals in amine tails [Zhang et al., 2023]
Size Range, mm
Weight Distribution, %
Apatite Monazite Xenotime Zircon Rutile
Pseudo-
rutile Leucoxene
–0.32+0.16 3.32
–0.16+0.08 44.68 11.07 24.96 30.10 21.56 24.46
–0.08+0.04 34.60 78.29 62.83 63.23 68.29 53.88
–0.04+0.02 12.13 8.54 86.71 10.21 5.95 9.13 15.94
–0.02+0.01 3.97 1.98 5.20 1.47 0.55 0.78 3.60
–0.01 1.30 0.12 8.09 0.53 0.17 0.24 2.12
Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00
2REPO4 +3H2SO4 =RE2(SO4)3 +2H3PO4 (1)
Ca5 (PO4)3 F +5H2SO4 =5CaSO4 +3H3PO4 +HF↑ (2)
where RE denotes element of rare earths.
RESULTS AND DISCUSSION
Pre-Concentration with Shaking Table
A representative sample of amine flotation tails was col-
lected from beneficiation plant at the Four Corner Mine,
one of the phosphate mines in central Florida. A represen-
tative sample of the tails was assayed for main components
and REE content, Table 1.
Quantitative mineral analysis was conducted using a
Mineral Liberation Analyzer (MLA). Two rare earth miner-
als were identified by MLA, they are monazite and xeno-
time, both at very low concentrations. Major non rare earth
minerals include quartz, fluorapatite, feldspar, zircon, and
rutile, Table 2.
The size range of the mineral particles was also analyzed
using MLA, Table 3.
A shaking table was used to concentrate the REEs-
bearing minerals and apatite from the amine flotation tail-
ings. The operating conditions of the shaking table were
optimized first and determined as follows:
• Transverse angle: 5°
• Stroke length: 7 mm
• Stroke frequency: 310 revolutions per minute
• Wash water: 3.5 gallons per minute
• Tailings feed: 583 grams per minute
Then 500 kilograms of the sample was used in shaking table
concentration, and the separation results are presented in
Table 4.
The pre-concentration removed up to 87.49 wt% of
solid from the feed and produced a concentrate with much
higher contents of REEs and P2O5 than those in the tail-
ings, but the recoveries of these two components were only
40.73% and 33.12%, respectively. It can be deduced from
the results that most of the valuable minerals in the amine
flotation tails existed in fine mineral particles interlocking
Table 1. Main chemical components in amine tails sample
Component Total REEs, ppm P2O5, %CaO, %Fe2O3, %MgO, %Al2O3, %
Content 201.96 3.01 5.62 0.29 0.02 0.28
Table 2. Quantitative mineral analysis of amine tails using MLA [Zhang et al., 2023]
Mineral Wt%% Mineral Wt%% Mineral Wt%%
Monazite 0.053 Tourmaline 0.353 Pseudo-rutile 1.125
Xenotime 0.003 Garnet 0.477 Rutile 0.450
Zircon 0.614 Epidote 0.119 Leucoxene 0.148
Apatite 8.703 Kyanite 1.174 Sphene 0.337
Wavellite 0.512 Staurolite 0.329 Limonite 0.016
Woodhouseite 0.009 Kaolin 0.048 Siderite 0.143
Quartz 80.011 Pyrite 0.047 Zinc spinel 0.003
Feldspar 5.294 Sphalerite 0.009 Others 0.003
Biotite 0.004 Calcite 0.003 Total 100.000
Table 3. Size distribution analysis for the major valuable minerals in amine tails [Zhang et al., 2023]
Size Range, mm
Weight Distribution, %
Apatite Monazite Xenotime Zircon Rutile
Pseudo-
rutile Leucoxene
–0.32+0.16 3.32
–0.16+0.08 44.68 11.07 24.96 30.10 21.56 24.46
–0.08+0.04 34.60 78.29 62.83 63.23 68.29 53.88
–0.04+0.02 12.13 8.54 86.71 10.21 5.95 9.13 15.94
–0.02+0.01 3.97 1.98 5.20 1.47 0.55 0.78 3.60
–0.01 1.30 0.12 8.09 0.53 0.17 0.24 2.12
Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00