1. University of Limerick
EVALUATION OF A REUSE TECHNOLOGY FOR BAUXITE RESIDUE – EXTRACTION OF GALLIUM
Éva Ujaczki, Patricia Cusack, Rama Krishna Chinnam, Seamus Clifford, Teresa Curtin, Ronan Courtney, Lisa O`Donoghue
University of Limerick

2. Importance of gallium
Ga compounds (e.g. GaAs, GaN, CIGS) provides semiconducting properties
Used for the production of microelectronic components e.g. photodiodes, cell phones, infrared emitting diodes, wireless communications
No primary Ga mines; Ga in the Earth’s crust is lower than < 19 ppm; Ga can be extracted from bauxite as part of the bauxite- alumina-aluminium refining flow
Ga is on the list of CRMs since the first report
in 2011; above average economic
importance and supply risk
Market price in 2017: 445 $ / kg

3. Bauxite residue used in the study
Produced by Bayer process
Stored after dewatering by vacuum filtration and mud farming at the disposal area
Moisture content of 28%
pH 10.9
Main composition: Al, Ca, Fe, Na, Ti, Si
Aqua regia accessible Ga concentration:
114 mg/kg
Origin
Ga [ppm]
Source
Earth crust 19
USGS
Australia 89
Wang et al., Sep. Purif. Technol. 108, 96–102 (2013).
China
570
Qu and Lian, Biores. Technol. 136, 16–23 (2013).
Hungary 27
Ujaczki et al., J. Chem. Technol. Biotechnol. 92(11), (2017).
India 91
Mohapatra et al., TMS 2012 Annual Meeting and Exhibition (Ed.: Suarez), pp. 87–90 (2012).
Turkey 25
Abdulvaliyev et al., Hydrometallurgy 157, 72–77 (2015).

4. Objectives Extractability: type of acid HCl, HNO3, H2SO4 and C2H2O4
process  parameters (acid concentration, time, T, S:L)
Purifying Ga from the leachate
adsorption
liquid-liquid extraction
By-product characterisation

5. Objectives Extractability: type of acid HCl, HNO3, H2SO4 and C2H2O4
process  parameters (acid concentration, time, T, S:L)
Purifying Ga from the leachate
adsorption
liquid-liquid extraction
By-product characterisation

6. Ga extractability Conditions normality = 2 24h duration 60 °C
100 g/L slurry conc.
250 rpm constant shaking

7. Process parameters
Ujaczki É., Cusack P., Clifford S., Curtin T., Courtney, R., O’Donoghue L. (2017) Proceedings of 35th International ICSOBA Conference, Hamburg, Germany. pp. 485–490.

8. Experimentally determined
Optimal conditions
DOE
optimal conditions for extraction
response: max. extractable Ga
Optimal conditions
2.5 M oxalic acid
22 h duration
80 °C
10 g/L slurry conc.
Experimentally determined
81.1 mg/kg
Predicted
85.8 mg/kg
Accuracy
93% 8

9. Objectives Extractability: type of acid HCl, HNO3, H2SO4 and C2H2O4
process  parameters (acid concentration, time, T, S:L)
Purifying Ga from the leachate
adsorption
liquid-liquid extraction
By-product characterisation

10. Zeolite adsorption
Kamonsawas et al., International Journal of Polymeric Materials 62(11) DOI /

11. Adsorbent amount (mg/cm3)
Zeolite adsorption
Zeolite products
SiO2/Al2O3 mole ratio
Nominal cation form
Pore size (Å)
Type
CBV 500
5.1
NH4+
7.4 Y
CP 811E-75 75
6.8
beta
CBV 2314 23
5.5
ZSM-5
CBV 500
CBV 2314
Adsorbent
Adsorbent amount (mg/cm3)
Contact time (h)
Temperature (℃)
Removal (%)
CBV 500 10 24 20
99.1±0.1
CP 811E-75
16.8±0.2
CBV 2314
21.0±3.2 CP

12. Adsorption parameters

13. Experimentally determined
Optimal parameters
DOE
optimal conditions for adsorption
response: maximum Ga removal %
Optimal conditions
5 mg/cm3 adsorbent
1 h contact time
20 °C
Experimentally determined
99.4 %
Predicted
99.8 %
Accuracy
99.6%

14. Ga adsorption on zeolite from leachate
Conditions
5 mg/cm3 adsorbent
1 h contact time
20 °C

15. Liquid-liquid extraction
Organophosphorus compound: D2EHPA
[Di-(2-ethylhexyl)phosphoric acid]
dissolved in Kerosene

16. Liquid-liquid extraction of Ga from leachate
Conditions
O/A=3
1M D2EHPA in Kerosene
1 h contact time
20 °C

17. Objectives Extractability: type of acid HCl, HNO3, H2SO4 and C2H2O4
process  parameters (acid concentration, time, T, S:L)
Purifying Ga from the leachate
adsorption
liquid-liquid extraction
By-product characterisation

18. By-product characterization
Bauxite residue
pH 10.9
EC 0.9 mS
By-product after leaching
pH 0.3
EC 39.1 mS
XRD by product and bauxite residue
Extraction with 2.5 M oxalic acid, 22 h, 80 °C, 10 g/L slurry conc.

19. By-product composition
Bauxite residue mapping EDS
By-product of leaching mapping EDS

20. Conclusion Ga could be efficiently extracted
Adsorption of Ga on zeolite has a potential
Extraction of Ga from the leachate is efficient but not selective
Value alone may not be the primary driver for extraction (avoidance waste, environmental /human health risks, reduce liabilities…)
Cheap processes needed: chance for bio-recovery?
Further study on the by-product needed: enrionmental risk, reuse potential

21. Project team Visit: http://alsource.eu/ Dr. Ronan Courtney
Dr. Lisa Maria T. O’Donoghue
Dr. Teresa Curtin
Ms. Patricia Cusack
Dr. Éva Ujaczki
Visit:

22. Thank you for your attention!
Contact:
Acknowledgements
We thank for financial support by the Al-Source (2014-RE-MS-1) funded by Irish EPA.