Synergistic effect of microwave irradiation and CaF₂ on vanadium leaching

Jing-peng Wang^1,2，Yi-min Zhang^1,2,3，Jing Huang^1,2,3，Tao Liu^1,2,3

1. School of Resource and Environmental Engineering,Wuhan University of Science and Technology2. Hubei Provincial Engineering Technology Research Center of High Efficient Cleaning Utilization for Shale Vanadium Resource

摘 要：The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride（Ca F₂） on the vanadium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when Ca F₂ is present. The leaching rate of vanadium under microwave irradiation is increased by 8%–15% when 5wt% Ca F₂ is added; by contrast,in the absence of Ca F₂,the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation,whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover,a large amount of Al and V and a small amount of Si are dissolved from samples under microwave heating,as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When Ca F₂ is present,the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer,resulting in a prominent effect of microwave irradiation.

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