PUBLICATIONS

LIBS, XRF and Raman sensors for optimal bauxite sorting
B Orberger, C Garcia-Piña, B de Waard, L Rybok, R HyypiÖ, A Prudhomme, L Capar, H Lindström, S Uusitalo, M Alamäki, C Kaminski, J A Meima and S Merk IMPC Asia-Pacific 2022 : 22-24 August2022, Melbourne Australia + online; The Australian Institute of Mining and Metallurgy; Publication series N° 5/2022 p. 437-462.

Abstract: Bauxite, bauxite residues (BR) and Bayer Liquor are important resources for Al, Sc, V and Ga. Bauxite is currently the solely source for primary aluminium. At global scale about 80 plants produce alumina. From these resources, about 1 to 1.4 tonnes of bauxite residues are generated per tonne of alumina (Ujaczko et al. 2018). Bauxites present heterogeneous grades at lateral and vertical scale, variable mineralogy, and chemistry. Therefore, it is important to localize most precisely minerals hosting valuable metals for Al, Sc, V and Ga, but also hazardous minerals/metals for processing such as reactive silica (aluminosilicates), TiO2 (rutile, anatase), and minerals generating moisture (phyllosilicates). This must be done at the beginning of the value chain on mine sites to reduce transport and processing costs, and BR volumes. In this study, different types of sensors were applied to major lithologies of the karst bauxite deposits of SODICAPEI (Villeveyrac, Southern France), for optimal bauxite sorting. Therefore, the applicability of Laser-Induced Breakdown Spectroscopy (LIBS) was investigated with an industrial LIBS system and a LIBS core scanning system. Furthermore, first time-gated Raman and XRF spectroscopic analyses were performed with the multi-sensor ANCORELOG system.Our results, obtained in the frame of the EIT ANCORELOG and T-REX projects, show that LIBS is powerful to precisely define the bottom and top layer of bauxite ores and define the bauxite types by measurement of major and trace elements (Al, Mg, K, Na, Ca, C, Si, Ti, Fe, S). Furthermore, LIBS can access the critical parameters crucial for bauxite processing. XRF gives semiquantitative data for Mn, Fe, Cr, Ti, V, Ca, K while time-gated Raman spectroscopy allows deciphering clay minerals, Ti-minerals, boehmite and carbonates, all allowing defining bauxite on and offset.

Efficient vanadium recovery from highly alkaline solution using Lanthanum doped Mg-Al LDH: A promising approach for sustainable resource extraction

Subhamoy Bhowmick, Bart Michielsen, Monika Kus, Steven Mullens, Pegie Cool, Elena Mihaela Seftel; Separation and Purification Technology 354 (2025) 128650

https://doi.org/10.1016/j.seppur.2024.128650 

Highlights:

• La doped Mg-Al LDH with varying Al/La molar ratio was prepared.

• La doping in the LDH increased the V sorption capacity in alkaline solution.

• The stability of the LDH particle increased from La doping in alkaline pH.

• V was removed from the solution by anion exchange mechanism.

• Adsorbed V was successfully recovered using 2 M NaNO₃ – 1 M NaOH mixed solution.

Abstract: Metal recyclability from secondary sources is vital in the context of circular economy. Vanadium (V) is one such critical metal due to its increasing demand in various industries. Herein, a series of NO₃^– intercalated Lanthanum (La)-doped Mg–Al layered double hydroxides (LDHs) were synthesized to remove V oxyanions from alkaline solution. Characterization of the synthesized material suggested that incorporation of La into the LDH structure did not change the basic layered structure of LDH but mainly affected the interlayer distances. Batch adsorption experiments showed that La doping enhanced the removal of V compared to pristine Mg-Al LDH, especially in alkaline solution and the V removal capacity was dependent upon the La content in the LDH. Pseudo-second order and inter-particle diffusion model were able to explain the V removal kinetics, and the sorption equilibrium data fitted well with the Langmuir model. Spectroscopic investigation of the spent LDH demonstrated that an anion exchange mechanism was mainly responsible for the V uptake from solution. Different concentrations of NaOH and NaNO₃ solution were investigated to recover the maximum amount of V adsorbed. Recyclability test showed that 2 M NaNO₃ – 1 M NaOH solution was not only able to recover most of the adsorbed V but could also regenerate the LDH activity, as tested for 5 cycles. Thus, the study clearly indicates that La-doping onto the Mg–Al LDH increases the LDH alkaline stability and can be a promising material for effective separation and recovery of V from alkaline secondary sources, ensuring resource sustainability.