An insight on the mechanism of efficient leaching of vanadium from vanadium shale induced by microwave-generated hot spots

Abstract

Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate. In this paper, microwave heating was used to improve the acid leaching, and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software. The effects of the microwave power, leaching temperature, CaF₂ dosage, H₂SO₄ concentration, and leaching time on the vanadium recovery were investigated. A vanadium recovery of 80.66% is obtained at a microwave power of 550 W, leaching temperature of 95°C, CaF₂ dosage of 5wt%, H₂SO₄ concentration of 20vol%, and leaching time of 2.5 h. Compared with conventional leaching technology, the vanadium recovery increases by 6.18%, and the leaching time shortens by 79.17%. More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process. Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field (E-field). The distributions of E-field and temperature among vanadium shale particles are relatively uniform, except for the higher content at the contact position of the particles. The analysis results of scale-up experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching, and the local high temperature destroys the mineral structure and accelerates the reaction rate.

Keywords

vanadium shale / microwave-assisted leaching / hot spots / numerical simulation

References

[1] Zhang YM, Bao SX, Liu T, Chen TJ, Huang J. The technology of extracting vanadium from stone coal in China: History, current status and future prospects. Hydrometallurgy, 2011, 109(1–2): 116.

[2] Gustafsson JP. Vanadium geochemistry in the biogeosphere-speciation, solid-solution interactions, and ecotoxicity. Appl. Geochem., 2019, 102, 1.

[3] del Carpio E, Hernández L, Ciangherotti C, et al. Vanadium: History, chemistry, interactions with α-amino acids and potential therapeutic applications. Coord. Chem. Rev., 2018, 372, 117.

[4] Hu PC, Zhang YM, Liu T, Huang J, Yuan YZ, Zheng QS. Highly selective separation of vanadium over iron from stone coal by oxalic acid leaching. J. Ind. Eng. Chem., 2017, 45, 241.

[5] B. Chen, S.X. Bao, Y.M. Zhang, and S. Li, A high-efficiency and sustainable leaching process of vanadium from shale in sulfuric acid systems enhanced by ultrasound, Sep. Purif. Technol., 240(2020), art. No. 116624.

[6] Yuan YZ, Zhang YM, Liu T, Hu PC, Zheng QS. Optimization of microwave roasting-acid leaching process for vanadium extraction from shale via response surface methodology. J. Cleaner. Prod., 2019, 234, 494.

[7] Yuan YZ, Zhang YM, Liu T, Chen TJ, Huang J. Source separation of V and Fe by two-stage selective leaching during V extraction from stone coal. RSC Adv., 2017, 7(30): 18438.

[8] Chen B, Bao SX, Zhang YM. Synergetic strengthening mechanism of ultrasound combined with calcium fluoride towards vanadium extraction from low-grade vanadium-bearing shale. Int. J. Min. Sci. Technol., 2021, 31(6): 1095.

[9] Li MT, Wei C, Fan G, Wu HL, Li CX, Li XB. Acid leaching of black shale for the extraction of vanadium. Int. J. Miner. Process., 2010, 95(1–4): 62.

[10] Wang MY, Xiao LS, Li QG, Wang XW, Xiang XY. Leaching of vanadium from stone coal with sulfuric acid. Rare Met., 2009, 28(1): 1.

[11] Zhang B, Gao ZG, Liu HZ, Wang W, Cao YH. Direct acid leaching of vanadium from stone coal. High Temp. Mater. Process., 2017, 36(9): 877.

[12] Zhang XY, Yang K, Tian XD, Qin WQ. Vanadium leaching from carbonaceous shale using fluosilicic acid. Int. J. Miner. Process., 2011, 100(3–4): 184.

[13] Elmahdy AM, Farahat M, Hirajima T. Comparison between the effect of microwave irradiation and conventional heat treatments on the magnetic properties of chalcopyrite and pyrite. Adv. Powder Technol., 2016, 27(6): 2424.

[14] Moravvej Z, Mohebbi A, Daneshpajouh S. The microwave irradiation effect on copper leaching from sulfide/oxide ores. Mater. Manuf. Process., 2018, 33(1): 1.

[15] T. Le, X.T. Li, A.V. Ravindra, Q. Wang, J.H. Peng, and S.H. Ju, Leaching behavior of contaminant metals from spent FCC catalyst under microwave irradiation, Mater. Res. Express, 6(2018), No. 3, art. No. 035509.

[16] L. Guo, J.R. Lan, Y.G. Du, T.C. Zhang, and D.Y. Du, Microwave-enhanced selective leaching of arsenic from copper smelting flue dusts, J. Hazard. Mater., 386(2020), art. No. 121964.

[17] Wen T, Zhao YL, Xiao QH, et al. Effect of microwave-assisted heating on chalcopyrite leaching of kinetics, interface temperature and surface energy. Results Phys., 2017, 7, 2594.

[18] Zhang LY, Mo JM, Li XH, Pan LP, Wei GT. Leaching reaction and kinetics of zinc from indium-bearing zinc ferrite under microwave heating. Russ. J. Non-Ferrous Met., 2016, 57(4): 301.

[19] Wang JP, Zhang YM, Huang J, Liu T. Synergistic effect of microwave irradiation and CaF₂ on vanadium leaching. Int. J. Miner. Metall. Mater., 2017, 24(2): 156.

[20] J.P. Wang, Y.M. Zhang, J. Huang, and T. Liu, Efficient microwave irradiation-assisted hydrothermal synthesis of ammonium vanadate flake, Cryst. Res. Technol., 52(2017), No. 12, art. No. 1700104.

[21] X. Qiao and X.Y. Xie, The effect of electric field intensification at interparticle contacts in microwave sintering, Sci. Reports, 6(2016), art. No. 32163.

[22] Ebadzadeh T. Effect of mechanical activation and microwave heating on synthesis and sintering of nano-structured mullite. J. Alloys Compd., 2010, 489(1): 125.

[23] Zhang XF, Liu FG, Xue XX, Jiang T. Effects of microwave and conventional blank roasting on oxidation behavior, microstructure and surface morphology of vanadium slag with high chromium content. J. Alloys Compd., 2016, 686, 356.

[24] A.J. Teng and X.X. Xue, A novel roasting process to extract vanadium and chromium from high chromium vanadium slag using a NaOH—NaNO₃ binary system, J. Hazard. Mater, 379(2019), art. No. 120805.

[25] H.Y. Gao, T. Jiang, M. Zhou, J. Wen, X. Li, Y. Wang, and X.X. Xue, Effect of microwave irradiation and conventional calcification roasting with calcium hydroxide on the extraction of vanadium and chromium from high-chromium vanadium slag, Miner. Eng., 145(2020), art. No. 106056.

[26] Yuan YZ, Zhang YM, Liu T, Chen TJ, Huang J. Comparison of microwave and conventional blank roasting and of their effects on vanadium oxidation in stone coal. J. Microwave Power Electromagn. Energy, 2016, 50(2): 81.

[27] Yuan YZ, Zhang YM, Liu T, Chen TJ. Comparison of the mechanisms of microwave roasting and conventional roasting and of their effects on vanadium extraction from stone coal. Int. J. Miner. Metall. Mater., 2015, 22(5): 476.

[28] E.A. Olevsky, A.L. Maximenko, and E.G. Grigoryev, Ponderomotive effects during contact formation in microwave sintering, Modelling Simul. Mater. Sci. Eng., 21(2013), No. 5, art. No. 055022.

[29] Rybakov KI, Olevsky EA, Semenov VE. The microwave ponderomotive effect on ceramic sintering. Scripta Mater., 2012, 66(12): 1049.

[30] Freeman SA, Booske JH, Cooper RF. Microwave field enhancement of charge transport in sodium chloride. Phys. Rev. Lett., 1995, 74(11): 2042.

[31] Demirskyi D, Agrawal D, Ragulya A. Neck growth kinetics during microwave sintering of copper. Scripta Mater., 2010, 62(8): 552.

[32] Wang X, Yang DJ, Srinivasakannan C, Peng JH, Duan XH, Ju SH. A comparison of the conventional and ultrasound-augmented leaching of zinc residue using sulphuric acid. Arab. J. Sci. Eng., 2014, 39(1): 163.

[33] Xiang JY, Huang QY, Lv XW, Bai CG. Extraction of vanadium from converter slag by two-step sulfuric acid leaching process. J. Clean. Prod., 2018, 170, 1089.

[34] Xiang JY, Huang QY, Lv XW, Bai CG. Effect of mechanical activation treatment on the recovery of vanadium from converter slag. Metall. Mater. Trans. B, 2017, 48(5): 2759.

[35] Yang QW, Xie ZM, Peng H, Liu ZH, Tao CY. Leaching of vanadium and chromium from converter vanadium slag intensified with surface wettability. J. Central South Univ., 2018, 25(6): 1317.

[36] Wang JP, Zhang YM, Huang J, Liu T. Kinetic and mechanism study of vanadium acid leaching from black shale using microwave heating method. JOM, 2018, 70(6): 1031.

[37] Wang F, Zhang YM, Huang J, et al. Mechanisms of aid-leaching reagent calcium fluoride in the extracting vanadium processes from stone coal. Rare Met., 2013, 32(1): 57.

[38] Sun J, Wang WL, Yue QY, et al. Review on microwave-metal discharges and their applications in energy and industrial processes. Appl. Energy, 2016, 175, 141.

[39] J.Y. Zhu, L.P. Yi, Z.Z. Yang, and M. Duan, Three-dimensional numerical simulation on the thermal response of oil shale subjected to microwave heating, Chem. Eng. J., 407(2021), art. No. 127197.