Phase transitions and surface property variations of bastnaesite in suspension roasting: A study of bastnaesite pyrolysis and cerium oxidation

Abstract

Roasting bastnaesite concentrates is a crucial process in extracting rare earths. This study explored an efficient suspension roasting technology and investigated the bastnaesite pyrolysis and cerium (Ce) oxidation. Relevant analytical tests were applied to evaluate the phase and surface property variations of bastnaesite, and isothermal kinetic analysis of bastnaesite pyrolysis and Ce oxidation was performed. The results revealed that bastnaesite decomposed rapidly and accompanied by Ce oxidation, and the gas-solid products were identified as CO₂, Ce₇O₁₂, La₂O₃, CeF₃ and LaF₃, with Ce oxidation restricted by bastnaesite pyrolysis. As roasting time prolonged, cracks and pores appeared on bastnaesite surface; the BET specific surface and pore diameter increased. In later roasting period, the pore diameter continued to increase but the specific surface decreased, assigned to particle fusion agglomeration and pore consolidation. Additionally, the surface C content reduced and Ce(IV) content increased gradually as roasting progressed. The reaction kinetics all followed Avrami-Erofeev equations, the reaction orders of bastnaesite pyrolysis and Ce oxidation decreased with decreasing reaction temperature. The calculated activation energies at lower temperatures were higher than those calculated at higher temperatures. This study analyzed the bastnaesite reaction mechanism to supply a reference for the application of suspension roasting technology in bastnaesite smelting.

Keywords

bastnaesite pyrolysis / cerium oxidation / suspension roasting / isothermal kinetics

References

[1] BalaramV. Rare earth elements: A review of applications, occurrence, exploration, analysis, recycling, and environmental impact [J]. Geoscience Frontiers, 2019, 10(4): 1285-1303.

[2] WangL-s, HuangX-w, YuY, et al.. Towards cleaner production of rare earth elements from bastnaesite in China [J]. Journal of Cleaner Production, 2017, 165: 231-242.

[3] TalanD, HuangQ-q. A review of environmental aspect of rare earth element extraction processes and solution purification techniques [J]. Minerals Engineering, 2022, 179107430.

[4] ChengS-k, LiW-b, HanY-x, et al.. Recent process developments in beneficiation and metallurgy of rare earths: A review [J]. Journal of Rare Earths, 2024, 42(4): 629-642.

[5] DushyanthaN, BatapolaN, IlankoonI M S K, et al.. The story of rare earth elements (REEs): Occurrences, global distribution, genesis, geology, mineralogy and global production [J]. Ore Geology Reviews, 2020, 122103521.

[6] CenP, BianX, LiuZ-n, et al.. Extraction of rare earths from bastnaesite concentrates: A critical review and perspective for the future [J]. Minerals Engineering, 2021, 171107081.

[7] JyothiR K, ThenepalliT, AhnJ W, et al.. Review of rare earth elements recovery from secondary resources for clean energy technologies: Grand opportunities to create wealth from waste [J]. Journal of Cleaner Production, 2020, 267122048.

[8] JordensA, ChengY P, WatersK E. A review of the beneficiation of rare earth element bearing minerals [J]. Minerals Engineering, 2013, 41: 97-114.

[9] MarionC, LiR-h, WatersK E. A review of reagents applied to rare-earth mineral flotation [J]. Advances in Colloid and Interface Science, 2020, 279102142.

[10] LiW-b, ChenJ-j, ZhouW-t, et al.. Effect of bastnaesite as reductant on hematite reduction during in situ suspension magnetization roasting of refractory iron ore under neutral atmosphere [J]. International Journal of Mining Science and Technology, 2022, 32(4): 877-886.

[11] NingJ-l, GaoP, YuanS, et al.. Highly efficient and green separation of iron from complex low-grade polymetallic ore via hydrogen-based mineral phase transformation [J]. Powder Technology, 2024, 433119177.

[12] HuangX-w, LongZ-q, WangL-s, et al.. Technology development for rare earth cleaner hydrometallurgy in China [J]. Rare Metals, 2015, 34(4): 215-222.

[13] LiW-b, ChenJ-j, ChengS-k, et al.. Thermal decomposition mechanism and kinetics of bastnaesite in suspension roasting process: A comparative study in N₂ and air atmospheres [J]. Journal of Rare Earths, 2024, 42(9): 1809-1816.

[14] MengD-l, WangM, FengZ-y, et al.. Behavior of phase transformation of Baotou mixed rare earth concentrate during oxidation roasting [J]. Journal of Rare Earths, 2022, 40(6): 981-987.

[15] ZhaoL-s, WangL-s, ShuaiG-h, et al.. Thermal decomposition and oxidation of bastnaesite concentrate in inert and oxidative atmosphere [J]. Journal of Rare Earths, 2018, 36(7): 758-764.

[16] ZhangQ, SunY-s, HanY-x, et al.. Pyrolysis mechanism of bastnaesite during roasting in N₂ atmosphere: An in situ study of gas products, phase transition, and kinetics [J]. Journal of Industrial and Engineering Chemistry, 2023, 124: 381-391.

[17] CenP, BianX, WuW-y. Isoconversional kinetic analysis of decomposition of bastnaesite concentrates with calcium hydroxide [J]. Journal of Rare Earths, 2020, 38(12): 1361-1371.

[18] ChengS-k, HanY-x, TangZ-d, et al.. Producing magnetite concentrate from iron tailings via suspension magnetization roasting: A pilot-scale study [J]. Separation Science and Technology, 2023, 58(7): 1372-1382.

[19] YuanS, XiaoH-x, WangR-f, et al.. Improved iron recovery from low-grade iron ore by efficient suspension magnetization roasting and magnetic separation [J]. Minerals Engineering, 2022, 186107761.

[20] ZouD, ChenJ, LiK, et al.. Phase transformation and thermal decomposition kinetics of a mixed rare earth concentrate [J]. ACS Omega, 2018, 3(12): 17036-17041.

[21] ZhangQ, SunY-s, HanY-x, et al.. Pyrolysis behavior of bastnaesite in an air environment: Thermodynamics, phase transition and kinetics [J]. Journal of the Taiwan Institute of Chemical Engineers, 2023, 152105188.

[22] AgrawalA, ChakrabortyS. A kinetic study of pyrolysis and combustion of microalgae Chlorella vulgaris using thermo-gravimetric analysis [J]. Bioresource Technology, 2013, 128: 72-80.

[23] SunY-s, HanY-x, WeiX-c, et al.. Non-isothermal reduction kinetics of oolitic iron ore in ore/coal mixture [J]. Journal of Thermal Analysis and Calorimetry, 2016, 123(1): 703-715.

[24] AttaouiA. Modeling and non-linear mechanisms in heterogeneous kinetics of the non-isothermal pyrolysis or hydropyrolysis for tarfaya oil shale (Morocco) [J]. International Journal of Advanced Research, 2023, 11(3): 712-723.

[25] ZhaoY-y, SunX, MengD-l, et al.. Effect of phase transition during roasting of Mountain Pass rare earth concentrate on leaching efficiency of rare earths [J]. Journal of Rare Earths, 2024, 42(2): 409-414.

[26] MengD-l, HuangX-w, FengZ-y, et al.. Thermal decomposition of Bayan Obo mixed rare earth concentrate under inert atmosphere [J]. Transactions of Nonferrous Metals Society of China, 2023, 33(1): 285-292.

[27] ZhangQ, SunY-s, HanY-x, et al.. Isothermal and non-isothermal decomposition mechanisms of bastnaesite during the hydrogen-based mineral phase transformation [J]. International Journal of Hydrogen Energy, 2024, 68: 929-939.

[28] WangH-h, LiM, ZhangD-l, et al.. Phase change, micro-structure and reaction mechanism during high temperature roasting of high grade rare earth concentrate [J]. Journal of Rare Earths, 2020, 38(10): 1140-1150.

[29] LalithambaH S, RaghavendraM, YatishK V. Efficient application of green synthesized CeO₂ nanoparticles for the preparation of selenoester derivatives of protected amino acids and production of biodiesel from annona squamosa oil [J]. Journal of Electronic Materials, 2022, 51(7): 3650-3659.

[30] ZakiA A, KhalafallaM, AlharbiK H, et al.. Synthesis, characterization and optical properties of chitosan-La₂O₃ nanocomposite [J]. Bulletin of Materials Science, 2022, 453128.

[31] ChukanovN, ChervonnyiAInfrared spectroscopy of minerals and related compounds [M], 2016, Berlin. Springer. .

[32] ThommesM, KanekoK, NeimarkA V, et al.. Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report) [J]. Pure and Applied Chemistry, 2015, 87(9–10): 1051-1069.

[33] WeiX-l, SunY-s, LiY-j, et al.. Recovering cobalt from cobalt oxide ore using suspension roasting and magnetic separation technique [J]. Journal of Materials Research and Technology, 2023, 27: 3005-3015.

[34] MullinsD R, OverburyS H, HuntleyD R. Electron spectroscopy of single crystal and polycrystalline cerium oxide surfaces [J]. Surface Science, 1998, 409(2): 307-319.

[35] RygelJ L, ChenY-s, PantanoC G, et al.. Local structure of cerium in aluminophosphate and silicophosphate glasses [J]. Journal of the American Ceramic Society, 2011, 94(8): 2442-2451.

[36] XuL-h, LiuC, DengJ-s, et al.. Flotation and adsorption of novel Gemini decyl-bishydroxamic acid on bastnaesite: Experiments and density functional theory calculations [J]. International Journal of Mining Science and Technology, 2023, 33(10): 1193-1202.

[37] YangB, HeJ-f. New insights into selective depression mechanism of Tamarindus indica kernel gum in flotation separation of fluorapatite and calcite [J]. Separation and Purification Technology, 2025, 354128787.

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Central South University