Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science, Environmental Microbiology and Biotechnology Group
- 01 WASTE RESULTING FROM EXPLORATION, MINING, QUARRYING, AND PHYSICAL AND CHEMICAL TREATMENT OF MINERALS
- 01 04 wastes from physical and chemical processing of non-metalliferous minerals
- 01 04 12 tailings and other wastes from washing and cleaning of minerals other than those mentioned in 01 04 07 and 01 04 11
The Bayer process is the primary method by which alumina (Al2O3) is produced from bauxite ore. In this hydrometallurgical process, caustic soda digestion under elevated temperature and pressure is used to leach soluble alumina minerals from the bauxite ore and subsequently precipitate technically pure aluminum hydroxide. From the pregnant leach solution, the residual mineral matrix is removed as a byproduct, commonly termed as bauxite residue or “red mud” (Adamson et al., 2013; Gräfe and Klauber, 2011).
According to Vind, J. et al, 2018, in the process flowsheet of Aluminium of Greece, Metallurgy Business Unit, Mytilineos S.A., (AoG), about 80% of the bauxite feed is from karst bauxite, mainly Greek origin. About 20% of feed is from lateritic bauxite originating from West Africa (Ghana, Awaso) or Brazil (Porto Trombetas). The suspended karst bauxite is digested at a high temperature, and then the lateritic bauxite suspension stream is introduced to the main karst bauxite slurry stream in the appropriate flashing stage. The karst bauxite slurry in AoG is digested at about 255 °C (Balomenos et al., 2009) and a pressure of about 5.8–6.0 MPa.
The current practice in AoG’s plant is to dewater the washed bauxite residue in filter presses and store the filter cake. This datasheet provides the properties of the filter cake, based on Vind, J. et al, 2018.
It has been reported that over a 15-year period, the concentration of rare earth elements (REE) as well as Sc in the bauxite residue of AoG has fluctuated only about 8%, indicating a stable and homogeneous occurrence of Sc in this material (Davris et al., 2017).
- Metals, semi-metals and their compounds
- aluminium
Standardized X-ray fluorescence (XRF),
- Metals, semi-metals and their compounds
- iron
standardized X-ray fluorescence (XRF),
- Other inorganic chemical compounds
- silicon
Standardized X-ray fluorescence (XRF)
- Metals, semi-metals and their compounds
- titanium
- Other inorganic chemical compounds
- calcium
- Other inorganic chemical compounds
- sodium
- Metals, semi-metals and their compounds
- chromium
Inductively coupled plasma mass spectrometry (ICP-MS) after lithium metaborate/tetraborate fusion
- Metals, semi-metals and their compounds
- vanadium
Inductively coupled plasma mass spectrometry (ICP-MS) after lithium metaborate/tetraborate fusion
- Metals, semi-metals and their compounds
- other metal
Instrumental neutron activation analysis (INAA).
Mineralogical composition of the studied bauxite residue representing XRD-crystalline phases: boehmite: 2%, diaspore: 13%, hematite: 31%, Goethite: 7.5%, anatase: 0.6%, rutile: 0.7%, calcite: 5%, quartz: 5%, chamosite: 3.7%, gibbsite: 2.5% .
Secondary phases formed during the Bayer process: Hydrogarnet:14.5%, cancrinite: 11%, pervskite: 4%, portlandite: 0.8% (Vind et al, 2018)
Based on various publications that used different analytical techniques, the average concentration of Sc in AoG’s bauxite residue is 121 ± 16 mg/ kg (n=24) (Vind et al, 2018)
1) Adamson, A.N., Bloore, E.J., Carr, A.R., 2013. Basic Principles of Bayer Process Design. In: Donaldson, D., Raahauge, B.E. (Eds.), Reprinted in Essential Readings in Light Metals. John Wiley & Sons Inc, pp. 100–117 (2013).
2) Balomenos, E., Giannopoulou, I., Panias, D., Paspaliaris, I., 2009. ENEXAL: Novel technologies for enhanced energy and exergy efficiencies in primary aluminium production industry. MJoM 15, 203–217.
3) Gräfe, M., Klauber, C., 2011. Bauxite residue issues: IV. Old obstacles and new pathways for in situ residue bioremediation. Hydrometallurgy 108, 46 59. http://dx.doi.org/10.1016/j.hydromet.2011.02.005.
4) Davris, P., Balomenos, E., Taxiarchou, M., Panias, D., Paspaliaris, I., 2017. Current and alternative routes in the production of rare earth elements. BHM Berg- Hüttenmänn. Monatshefte 162, 245–251. http://dx.doi.org/10.1007/s00501-017-0610-y.
5) Vind, J., Malfliet, A., Bonomi, C., Paiste, P., Sajó, I.E., Blanpain, B., Tkaczyk, A.H., Vassiliadou, V., Panias, D. (2018) Modes of occurrences of scandium in Greek bauxite and bauxite residue, Minerals Engineering 123, 35–48.