Synergetic strengthening mechanism of ultrasound combined with calcium fluoride towards vanadium extraction from low-grade vanadium-bearing shale

• Published in: 矿业科学技术学报（英文版） Vol. 31; no. 6; pp. 1095 - 1106
• Main Authors: Bo Chen, Shenxu Bao, Yimin Zhang
• Format: Journal Article
• Language: English
• Published: Hubei Key Laboratory of Mineral Resources Processing and Environment,Wuhan 430070,China 2021; School of Resources and Environmental Engineering,Wuhan University of Technology,Wuhan 430070,China%School of Resources and Environmental Engineering,Wuhan University of Technology,Wuhan 430070,China; State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,Wuhan University of Science and Technology,Wuhan 430081,China%School of Resources and Environmental Engineering,Wuhan University of Technology,Wuhan 430070,China; State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,Wuhan University of Science and Technology,Wuhan 430081,China; Hubei Collaborative Innovation Center for High Efficient Utilization of Vanadium Resources,Wuhan University of Science and Technology,Wuhan 430081,China
• Subjects: Synergetic effect; Leaching kinetics; Vanadium-bearing shale; Ultrasound; CaF2 addition
• ISSN: 2095-2686
• DOI: 10.3969/j.issn.2095-2686.2021.06.012

The effect and mechanism of ultrasound and CaF2 on vanadium leaching from vanadium-bearing shale were investigated systematically. In consideration of the enhancement for vanadium recovery, the com-bination of ultrasound and CaF2 (66.28％) exerts more evident effects than ultrasound (26.97％) and CaF2 (60.35％) alone, demonstrating the synergetic effect of ultrasound and CaF2. Kinetic analysis manifests that the product layer diffusion controls vanadium leaching in ultrasound system without CaF2, however product layer diffusion and interfacial reaction is the rate-controlling step for vanadium leaching in other three leaching systems. The combination of ultrasound and CaF2 notably decreases the activation energy (Ea) from 62.03 to 27.61 kJ/mol, nevertheless individual CaF2 only reduces the Ea to 50.70 kJ/mol. X-ray diffraction and fourier transform infrared spectrometer analyses show that the decomposition degree of the vanadium-bearing mica structure is the most significant in ultrasound and CaF2 system, proving the highest release degree of vanadium. Specific surface area and pore distribution combined with scan-ning electron microscope analyses reveal that the action of ultrasound and CaF2 would provide higher specific surface area, more abundant pores structure and cracks for the particles, which further prompts the rapid diffusion of H+, F- and HF, and achieves the conspicuous improvement of vanadium leaching recovery.