Objective Background Introduction Conclusions/Future Work The Effects of Microwave Treatment on the Froth Flotation of Rare Earth Elements Kaleb Allen – Department of Materials Engineering – [email protected] Supervisor: Prof. Kristian Waters, Adam Jordens •Determine possible reagents for froth flotation and the effects of microwaves on the Thor Lake RE ore. Froth Flotation of REE Effects of Microwaves on Flotation •Microwaves are a form of electromagnetic radiation. •Materials that absorb microwave radiation are called dielectrics. •When a dielectric absorbs microwaves, the material loses stored energy as heat. • Since ore is made up of various minerals, the differences in heating between each mineral causes stresses to occur within the structure of the ore. •This could increase the recovery of REE due to the intergranular fractures between the ore’s particles. •A physico-chemical separation process using differences in the hydrophobicity of particles so that desired minerals rise as froth and gangue sits at the bottom of the cell. Rare earth elements (REE) are a group of elements that have unique properties allowing them to be used in magnets, electronics, metal alloys, and other technological fields. China produces roughly 94% of the world’s REE. (3) With China restricting its exports of REE to the rest of the world, other options must be explored to meet growing demand for these minerals. Avalon Rare Metals Inc. is currently exploring rare earth deposits in Thor Lake, NT. These deposits have the potential to be the largest producer of HREE. (6) However, there is no knowledge of how to process the ore. 2.65 64.91 60.19 56.13 63.19 8.68 18.47 15.09 11.73 5.87 15.45 19.85 23.61 1.97 3.50 5.01 43.91 7.74 5.48 1.13 8.19 6.45 9.48 21.76 9.89 19.88 22.84 34.32 58.47 59.68 60.96 25.91 28.55 29.00 60.34 59.66 60.91 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 None Sodium Oleate Sodium Oleate Sodium Oleate Sodium Oleate Benzohydroxamic acid Benzohydroxamic acid Benzohydroxamic acid Benzohydroxamic acid N-Benzoyl-N-phenylhydroxylamine Flotinor 1683 Flotinor SM15 Flotinor SM15 Sodium Oleate w/ Sodium Silcate Sodium Oleate w/ Sodium Silcate Sodium Oleate w/ Sodium Silcate Sodium Oleate w/ Citric acid Sodium Oleate w/ Both Benzo. Acid w/ Sodium Silicate Benzo. Acid w/ Sodium Silicate Benzo. Acid w/ Citric acid Benzo. Acid w/ Both Flotinor SM15 w/ Sodium Silicate Flotinor SM15 w/ Citric acid Flotinor SM15 w/ Both Benzo. acid (MW 2min) Benzo. acid (MW 2min) Benzo. acid (MW 2min) Sodium Oleate (MW 2min) Sodium Oleate (MW 2min) Sodium Oleate (MW 2min) Benzo. acid (MW 4min) Benzo. acid (MW 4min) Benzo. acid (MW 4min) Sodium Oleate (MW 4min) Sodium Oleate (MW 4min) Sodium Oleate (MW 4min) % Total Conc. w/ values Mass Pull of Preliminary and Microwave Treated Flotation of Thor Lake Ore Collector + Depressant(s) Used • 500g samples were floated using collectors for each type of reagent. •Three collectors (one from each type of reagent) were selected for further testing: -Sodium Oleate, -Benzohydroximic acid -Flotinor SM15. •Samples were then used to test the effects of adding depressants to RE flotation: -Sodium Silicate -Citric acid -Combination •Benzohydroximic acid showed an increase in the mass pull of microwaved samples compared to normal samples when floated (av. 13.49% to av.25.68% at 2min, av.27.82% at 4min) •Some microwave-treated concentrates using Benzo. acid produced a stable froth that was not seen in untreated samples. •Due to time constraints, only Sodium Oleate and Benzohydroximic acid were then treated with microwave radiation •For each collector, samples were microwaved at 800Wh for 2min and 4min before being ground and floated. •The hydrophobicity can be altered using reagents; collectors, depressants, and pH modifiers •When floating RE ore, previous studies have shown: -Carboxiylic Acids (Sodium Oleate) -Hydroxamic Acids( both Benzo-acids) -Organic Phosphoric Acids (both Flotinors) as effective collectors for separating RE minerals. Figure 1: Flotation Separation Cell Diagram (1) (a) (b) Figure 2 : (a) Scanned electron micrograph of as- received samples (non- microwave treated) and (b) microwave treated sample showing intergranular thermal stress cracking (5) Figure 3: Denver Flotation Cell (a) (b) (c) Figure 4: (a) Sample of Benzohydroximic Acid during flotation (b) microwave treated sample during flotation and (c) microwave sample’s concentrate showing stable froth after collection •Due to time constraints of the project, there was no time to complete a mineral analysis of all tested samples. When samples have been analyzed, it will be possible to examine the recovery of REE in the concentrate and determine the effectiveness of each collector. •When treated with microwave radiation, samples using Benzo. acid showed an increase in mass pull and in some cases the production of a stable froth. •Additional flotation tests to confirm results of tested collectors/depressants are needed. •Complete mineral analysis of all tested samples is needed. •Further research on the effects of microwave treated flotation using Benzo. acid and Flotinor SM15. Method/Results References (1) Flotation Separation Cell. Art. EncyclopaediaBritannica Online. <http://www.britannica.com/EBchecked/media/1524/Schematic-diagram-of-a- flotation-separation-cell>. (2) Long, K. The future of rare earth elements: Will these high-tech industry elements continue in short supply?. Tucson,AZ: Western Mineral and Environmental Resource Science Center. (3) Ren, J., Wang, W., Luo, J., Zhou, G., & Tang, F. (2003). Progress of flotation reagents of rare earth metals in china. Journal of Rare Earths, 21(1), 1-8. (4) Sahyoun, C. (2004). The effect of microwave radiation on the liberation of minerals from ores. Brimingham, England: Department of Chemical Engineering, University of Brimingham. (5) Thor lake introduction. (n.d.). Retrieved from http://avalonraremetals.com/projects/thor_lake/thor_lake_intro/
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Objective
Background
Introduction
Conclusions/Future Work
The Effects of Microwave Treatment on the Froth Flotation of Rare Earth Elements Kaleb Allen – Department of Materials Engineering – [email protected]
Supervisor: Prof. Kristian Waters, Adam Jordens
•Determine possible reagents for froth flotation and the effects of microwaves on the Thor Lake RE ore.
Froth Flotation of REE
Effects of Microwaves on Flotation
•Microwaves are a form of electromagnetic radiation. •Materials that absorb microwave radiation are called dielectrics. •When a dielectric absorbs microwaves, the material loses stored energy as heat. • Since ore is made up of various minerals, the differences in heating between each mineral causes stresses to occur within the structure of the ore. •This could increase the recovery of REE due to the intergranular fractures between the ore’s particles.
•A physico-chemical separation process using differences in the hydrophobicity of particles so that desired minerals rise as froth and gangue sits at the bottom of the cell.
Rare earth elements (REE) are a group of elements that have unique properties allowing them to be used in magnets, electronics, metal alloys, and other technological fields. China produces roughly 94% of the world’s REE. (3) With China restricting its exports of REE to the rest of the world, other options must be explored to meet growing demand for these minerals. Avalon Rare Metals Inc. is currently exploring rare earth deposits in Thor Lake, NT. These deposits have the potential to be the largest producer of HREE.(6) However, there is no knowledge of how to process the ore.
2.65
64.91 60.19
56.13
63.19
8.68
18.47 15.09
11.73 5.87
15.45 19.85 23.61
1.97 3.50 5.01
43.91
7.74 5.48
1.13
8.19 6.45
9.48
21.76
9.89 19.88
22.84
34.32
58.47 59.68
60.96
25.91 28.55 29.00
60.34 59.66 60.91
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
No
ne
Sod
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Sod
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Silc
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Sod
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Sod
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Sod
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Ben
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Ben
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(M
W 2
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Sod
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(MW
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Sod
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(MW
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Sod
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Sod
ium
Ole
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(MW
4m
in)
% Total Conc. w/ values
Mass Pull of Preliminary and Microwave Treated Flotation of Thor Lake Ore
Collector + Depressant(s) Used
• 500g samples were floated using collectors for each type of reagent.
•Three collectors (one from each type of reagent) were selected for further testing: -Sodium Oleate, -Benzohydroximic acid -Flotinor SM15. •Samples were then used to test the effects of adding depressants to RE flotation: -Sodium Silicate -Citric acid -Combination
•Benzohydroximic acid showed an increase in the mass pull of microwaved samples compared to normal samples when floated (av. 13.49% to av.25.68% at 2min, av.27.82% at 4min) •Some microwave-treated concentrates using Benzo. acid produced a stable froth that was not seen in untreated samples.
•Due to time constraints, only Sodium Oleate and Benzohydroximic acid were then treated with microwave radiation •For each collector, samples were microwaved at 800Wh for 2min and 4min before being ground and floated.
•The hydrophobicity can be altered using reagents; collectors, depressants, and pH modifiers •When floating RE ore, previous studies have shown: -Carboxiylic Acids (Sodium Oleate) -Hydroxamic Acids( both Benzo-acids) -Organic Phosphoric Acids (both Flotinors) as effective collectors for separating RE minerals.
Figure 1: Flotation Separation Cell Diagram(1)
(a) (b)
Figure 2: (a) Scanned electron micrograph of as- received samples (non-microwave treated) and (b) microwave treated sample showing intergranular thermal stress cracking(5)
Figure 3: Denver Flotation Cell
(a) (b) (c)
Figure 4: (a) Sample of Benzohydroximic Acid during flotation (b) microwave treated sample during flotation and (c) microwave sample’s concentrate showing stable froth after collection
•Due to time constraints of the project, there was no time to complete a mineral analysis of all tested samples. When samples have been analyzed, it will be possible to examine the recovery of REE in the concentrate and determine the effectiveness of each collector. •When treated with microwave radiation, samples using Benzo. acid showed an increase in mass pull and in some cases the production of a stable froth. •Additional flotation tests to confirm results of tested collectors/depressants are needed. •Complete mineral analysis of all tested samples is needed. •Further research on the effects of microwave treated flotation using Benzo. acid and Flotinor SM15.
Method/Results
References (1) Flotation Separation Cell. Art. EncyclopaediaBritannica Online. <http://www.britannica.com/EBchecked/media/1524/Schematic-diagram-of-a-flotation-separation-cell>. (2) Long, K. The future of rare earth elements: Will these high-tech industry elements continue in short supply?. Tucson,AZ: Western Mineral and Environmental Resource Science Center. (3) Ren, J., Wang, W., Luo, J., Zhou, G., & Tang, F. (2003). Progress of flotation reagents of rare earth metals in china. Journal of Rare Earths, 21(1), 1-8. (4) Sahyoun, C. (2004). The effect of microwave radiation on the liberation of minerals from ores. Brimingham, England: Department of Chemical Engineering, University of Brimingham. (5) Thor lake introduction. (n.d.). Retrieved from http://avalonraremetals.com/projects/thor_lake/thor_lake_intro/
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