Role of Oxidant and Fluoride in Stone Coal-Type Vanadium Ore Leaching Process Based on SEM and Element Mapping Analysis
LIU Ming-bao1, 2, ZHANG Tian1, 2, LI Feng1, 2, LIU Heng1, 2, YIN Wan-zhong3
1. Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources, Shangluo 726000, China
2. College of Chemical Engineering and Modern Material, Shangluo University, Shangluo 726000, China
3. School of Resources and Civil Engineering, Northeastern University, Northeastern University, Shenyang 110004, China
Abstract：Vanadium-bearing mica in stone coal vanadium ore serves as one of the important vanadium source minerals. While the presence of oxidizing agents and fluorides significantly enhances vanadium leaching efficiency, the underlying mechanisms remain incompletely understood. This study focuses on the ShanYang stone coal vanadium deposit in Shangluo, Shaanxi Province. Using a thermostatic waterbath-sulfuric acid leaching technique，the effects of oxidizing agents and fluoride systems, including binary fluorides of GroupⅠ, Ⅱ, Ⅲ metals, hydrofluorides (K+/Na+/NH+4), and hexafluoro-silicates/aluminates/phosphates, on vanadium leaching are systematically investigated. Through SEM and element mapping analysis, the primary pathways by which oxidants and fluorides promote vanadium leaching are clarified for the first time. Results indicate that the “pore corrosion” and “crevice corrosion” induced by the oxidant and fluorides are the main ways for efficient vanadium leaching. The effects of Group Ⅰ, Ⅱ metallic fluorides have been found to follow the order: CsF>KF>NaF>LiF, BaF2>SrF2>CaF2>MgF2，aligning with the lattice energies of these fluorides and the standard Gibbs free energy changes for HF production via reactions of these fluorides with leaching agent(sulfuric acid). In hexafluorosilicate/aluminate/phosphate systems, Na2SiF6 predominantly induces “pore corrosion”, while (NH4)2SiF6 generates extensive “crevice corrosion”traces. Faster HF mass transfer in fissure corrosion explains their divergent leaching efficiencies at varying dosages. Na3AlF6 forms colloidal aggregates that hinder mass transfer, resulting in lower leaching efficiency compared to (NH4)3AlF6, as confirmed by Al mapping in the residues. PF-6 exhibits weaker dissociation than SiF2-6/AlF3-6 due to stronger P—F bonds (vs. Si—F/Al—F), making NH4PF6 less effective. Hydrofluorides (KHF2>NH4HF2>NaHF2) achieve superior leaching via “pore corrosion”, with KHF2 achieving 96.0% vanadium recovery-the highest among all fluorides. SEM confirms the presence of abundant corrosion pores in KHF2 residues. This work provides theoretical and technical foundations for optimizing vanadium extraction from stone coal.
Key words：Vanadium extraction from stone coal; Leaching; Aid-Leaching reagent; Vanadium; Oxidizing leaching
刘明宝，张 甜，李 峰，刘 恒，印万忠. 氧化剂及氟化物对石煤钒矿浸出特性的SEM和Mapping分析[J]. 光谱学与光谱分析, 2025, 45(09): 2606-2613.
LIU Ming-bao, ZHANG Tian, LI Feng, LIU Heng, YIN Wan-zhong. Role of Oxidant and Fluoride in Stone Coal-Type Vanadium Ore Leaching Process Based on SEM and Element Mapping Analysis. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(09): 2606-2613.
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