Reaction mechanism of alumina, sulfur and gallium in desulfurization concentrate from diasporic bauxite during high-temperature digestion

Abstract

To mitigate the detrimental effects of sulfur and enhance the enrichment efficiency of valuable elements in desulfurized diasporic bauxite, the effects of CaO dosage, caustic alkali concentration, reaction temperature and time on the digestion behavior of alumina, sulfur and gallium were illustrated, and the digestion thermodynamics and mechanism were also revealed. During high-temperature Bayer process, alumina and gallium were digested synergistically, while pyrite is digested to S²⁻ and SO₄²⁻. Appropriate CaO dosage promotes the digestion of alumina and gallium, and facilitates the precipitation of sulfur as calcium sulfoaluminate hydrate, effectively removing sulfur from the solution. Excess CaO leads the formation of hydrogarnet, wherein Ga³⁺ incorporates into the crystal lattice by substituting for Al³⁺, reducing the digestion efficiency of gallium. Under the right conditions (CaO dosage = 3%, T = 260°C, t = 60 min, caustic alkali concentration = 260 g·L⁻¹), the corresponding alumina and gallium digestion efficiencies reach 90.82% and 77.58%, respectively, with a significantly reduced sulfur concentration of 1.32g·L⁻¹ in the solution. This work provides theoretical guidance for the efficient co-extraction of alumina and gallium from high-sulfur bauxite via the Bayer process.

Keywords

desulfurization concentrate / bayer process / alumina / gallium / high-temperature digestion

References

[1] Liu Y-s, Liu Y, Zhang T-a, et al.. Summary of sulfur hazards in high-sulfur bauxite and desulfurization methods [J]. Science of the Total Environment, 2024, 948: 174631.

[2] Chen Y, Zhang T-a, Lv G-z, et al.. Extraction and utilization of valuable elements from bauxite and bauxite residue: A review [J]. Bulletin of Environmental Contamination and Toxicology, 2022, 109(1): 228-237.

[3] Li X-b, Niu F, Liu G-h, et al.. Effects of iron-containing phases on transformation of sulfur-bearing ions in sodium aluminate solution [J]. Transactions of Nonferrous Metals Society of China, 2017, 27(4): 908-916.

[4] Zhu Z-p, Teng X, Yang Y, et al.. Flotation decarbonization and desulfurization of a high-sulfur bauxite in China [J]. Minerals, 2023, 13(8): 1008.

[5] Wang S-k, Niu F, Wang Y-l, et al.. Effects of S²⁻ and S₂O₃²⁻ containing bayer solutions on corrosion of 16Mn low-alloy steel at elevated temperatures [J]. Jom, 2021, 73(12): 3920-3927.

[6] Liu Z-w, Li D-y, Ma W-h, et al.. Sulfur removal by adding aluminum in the bayer process of high-sulfur bauxite [J]. Minerals Engineering, 2018, 119: 76-81.

[7] Tan C, Chen C-y, Li J-q, et al.. The desulfurization and digestion property of high-sulfur bauxite with coarse-grained particles by roasting: Desulfurization ratio and digestion kinetics [J]. Transactions of the Indian Institute of Metals, 2022, 75(7): 1821-1830.

[8] Cheng G, Li Y-l, Zhang M-ni. Research progress on desulfurization technology of high-sulfur bauxite [J]. Transactions of Nonferrous Metals Society of China, 2022, 32(10): 3374-3387.

[9] Xie M-z, Liu F-q, Zhao H-liang. Characterization of high sulfur bauxite and its phase transformation during desulfurization: A perspective from process mineralogy [J]. Journal of Sustainable Metallurgy, 2023, 9(4): 1466-1476.

[10] Lou Z-n, Xiong Y, Feng X-d, et al.. Study on the roasting and leaching behavior of high-sulfur bauxite using ammonium bisulfate [J]. Hydrometallurgy, 2016, 165: 306-311.

[11] Wu H-f, Chen C-y, Li J-q, et al.. Digestion mechanism and crystal simulation of roasted low-grade high-sulfur bauxite [J]. Transactions of Nonferrous Metals Society of China, 2020, 30(6): 1662-1673.

[12] Wang R-f, Yuan S, Gao P, et al.. Application of suspension magnetization roasting as technology for high-efficiency separation of valuable iron minerals from high-iron bauxite [J]. Transactions of Nonferrous Metals Society of China, 2022, 32(7): 2391-2402.

[13] Zhang Y, Liu R-q, Sun W, et al.. Electrochemical mechanism and flotation of chalcopyrite and galena in the presence of sodium silicate and sodium sulfite [J]. Transactions of Nonferrous Metals Society of China, 2020, 30(4): 1091-1101.

[14] Cheng G, Zhang J-q, Su H-h, et al.. Synthesis and characterization of a novel collector for the desulfurization of fine high-sulfur bauxite via reverse flotation [J]. Particuology, 2023, 79: 64-77.

[15] Sun Q, Wang S, Ma X, et al.. Desulfurization in high-sulfur bauxite with a novel thioether-containing hydroxamic acid: Flotation behavior and separation mechanism [J]. Separation and Purification Technology, 2021, 275: 119147.

[16] Lü A-j, Shen Y-q, Gong X-z, et al.. Effects of electrolyte recycling on desulfurization from bauxite water slurry electrolysis [J]. Transactions of Nonferrous Metals Society of China, 2016, 26(6): 1714-1720.

[17] Blight K, Ralph D E, Thurgate S. Pyrite surfaces after bio-leaching: A mechanism for bio-oxidation [J]. Hydrometallurgy, 2000, 58(3): 227-237.

[18] Xu J, Liu X-r, Song C-l, et al.. Biodesulfurization of high sulfur coal from Shanxi: Optimization of the desulfurization parameters of three kinds of bacteria [J]. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020, 42(18): 2297-2315.

[19] Liu Z-w, Yan H-w, Ma W-h, et al.. Digestion behaviors of sulfur-containing minerals and desulfuration during alumina production process [J]. Minerals Engineering, 2021, 173: 107234.

[20] Li X-h, Zhang Q, Qiu Y-q, et al.. Correlation between clay minerals, rheology, and flotation in the desulfurized pulp of high-sulfur bauxite [J]. Langmuir, 2025, 41(21): 13166-13183.

[21] Liu Z-w, Li W-x, Ma W-h, et al.. Comparison of deep desulfurization methods in alumina production process [J]. Journal of Central South University, 2015, 22(10): 3745-3750.

[22] Zhou X-j, Yin J-g, Chen Y-l, et al.. Simultaneous removal of sulfur and iron by the seed precipitation of digestion solution for high-sulfur bauxite [J]. Hydrometallurgy, 2018, 181: 7-15.

[23] Liu Z-w, Yan H-w, Ma W-h, et al.. Digestion behavior and removal of sulfur in high-sulfur bauxite during bayer process [J]. Minerals Engineering, 2020, 149: 106237.

[24] Wang S-k, Wang Y-l, Qi T-g, et al.. Effect of redox agents on the reaction behavior of pyrite in sodium aluminate solution at elevated temperatures [J]. Minerals Engineering, 2023, 191: 107974.

[25] Zhou X-j, Chen Y-l, Yin J-g, et al.. Study on Bayer digestion behaviour of low grade bauxite with high sulphur [J]. International Journal of Microstructure and Materials Properties, 2018, 13(3/4): 173.

[26] Frenzel M, Ketris M P, Seifert T, et al.. On the current and future availability of gallium [J]. Resources Policy, 2016, 47: 38-50.

[27] Zhao Z, Yang Y-x, Xiao Y-p, et al.. Recovery of gallium from Bayer liquor: A review [J]. Hydrometallurgy, 2012, 125–126: 115-124.

[28] Ujaczki É, Courtney R, Cusack P, et al.. Recovery of gallium from bauxite residue using combined oxalic acid leaching with adsorption onto zeolite HY [J]. Journal of Sustainable Metallurgy, 2019, 5(2): 262-274.

[29] Lu F-h, Xiao T-f, Lin J, et al.. Recovery of gallium from Bayer red mud through acidic-leaching-ion-exchange process under normal atmospheric pressure [J]. Hydrometallurgy, 2018, 175: 124-132.

[30] Qu Y, Li H, Tian W-j, et al.. Leaching of valuable metals from red mud via batch and continuous processes by using fungi [J]. Minerals Engineering, 2015, 81: 1-4.

[31] Li X-b, Fu W-a, Zhou Q-s, et al.. Reaction behavior and mechanism of anatase in digestion process of diasporic bauxite [J]. Transactions of Nonferrous Metals Society of China, 2010, 20(1): 142-146.

[32] Qi H, Gong N, Zhang S-q, et al.. Research progress on the enrichment of gallium in bauxite [J]. Ore Geology Reviews, 2023, 160: 105609.

[33] Dudek K, Jones F, Radomirovic T, et al.. The effect of anatase, rutile and sodium titanate on the dissolution of boehmite and gibbsite at 90 °C [J]. International Journal of Mineral Processing, 2009, 93(2): 135-140.

[34] Zhou G-t, Wang Y-l, Qi T-g, et al.. Enhanced conversion mechanism of Al-goethite in gibbsitic bauxite under reductive Bayer digestion process [J]. Transactions of Nonferrous Metals Society of China, 2022, 32(9): 3077-3087.

[35] Pan X-l, Wu H-f, Yu H-y, et al.. Precipitation of desilication products in CaO-Na₂O-Al₂O₃-SiO₂-H₂O system based on the Bayer process [J]. Hydrometallurgy, 2020, 197: 105469.

[36] Pan X-l, Yu H-y, Tu G-feng. Reduction of alkalinity in bauxite residue during Bayer digestion in high-ferrite diasporic bauxite [J]. Hydrometallurgy, 2015, 151: 98-106.

[37] Ge C-q, Zhao Y-r, Li C-c, et al.. Preparation and property studies of ferric sulfoaluminate cement based on Bayer red mud and phosphogypsum [J]. Environmental Science and Pollution Research, 2024, 31(25): 37594-37609.

[38] Roosen J, Mullens S, Binnemans K. Chemical immobilization of 8-hydroxyquinoline and 8-hydroxyquinaldine on chitosan-silica adsorbent materials for the selective recovery of gallium from Bayer liquor [J]. Hydrometallurgy, 2017, 171: 275-284.

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