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Impact of reactive oxygen species on Fe(II) oxidation and pyrite floatability under alkaline conditions
Minerals Engineering ( IF 4.9 ) Pub Date : 2025-05-17 , DOI: 10.1016/j.mineng.2025.109392
Xiaopeng Niu, Haiping Zhao, Shihong Xu, Xianbing Jia, Yan Jia, Renman Ruan
Minerals Engineering ( IF 4.9 ) Pub Date : 2025-05-17 , DOI: 10.1016/j.mineng.2025.109392
Xiaopeng Niu, Haiping Zhao, Shihong Xu, Xianbing Jia, Yan Jia, Renman Ruan
The generation of reactive oxygen species (ROS) such as H2 O2 and • OH during pyrite grinding and their impact on flotation under acidic conditions is well documented, yet their role in alkaline systems remains unclear. This study investigates the impact of ROS on fine pyrite floatability at alkaline pH, with a focus on ROS effect on Fe2+ oxidation. Surface oxidation products and collector adsorption were systematically analyzed using X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS). Electron Paramagnetic Resonance (EPR) revealed that ROS (e.g., H2 O2 and • OH) formed spontaneously during pyrite grinding, with their types and concentrations varying across slurry pH levels. At pH 8, Fe2+ addition depressed pyrite flotation, whereas sodium citrate addition enhanced pyrite floatability. Tof-SIMS and XPS analyses demonstrated that conditioning fine pyrite in a mixture of Fe2+ and H2 O2 solution reduced the normalized intensity of C4 H9 OCS2 - (collector species) while increasing of FeOOH- signals, suggesting that iron oxide/hydroxide species (e.g., FeOOH) inhibited collector adsorption. Critically, Fe2+ oxidation experiments confirmed that ROS accelerated Fe2+ oxidation and subsequent precipitation under alkaline conditions. These results indicated that fine pyrite depression at alkaline pH arose primarily from Fe(II) oxidation and precipitation, rather than direct ROS-induced surface oxidation. By introducing an iron-complexing agent (e.g., sodium citrate), the oxidation and precipitation of Fe(II) was mitigated, alleviating pyrite depression, as validated through tests on Carlin-type gold ores from Northwestern China. This work advances fundamental understanding of ROS interactions with pyrite at alkaline pH and propose practical engineering solutions to enhance gold recovery from refractory Carlin-type deposits.
更新日期：2025-05-17
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