Abstract:The effects of Ca 2+ , Mg 2+ , Al 3+ , and Fe 3+ on the flotation behaviors of apatite, dolomite and quartz were investigated through a micro-flotation test, and the influence of calcium ions on the flotation of these minerals was further elucidated by solution chemistry study, zeta potential measurement, and X-ray photoelectron spectroscopy (XPS) analyses. The results indicate that an appropriate amount of Ca 2+ and Mg 2+ can improve the floatability of apatite but had a negligible effect on the flotation performance of dolomite, whereas Al 3+ , Fe 3+ , and excessive amounts of Ca 2+ decreased the recovery of apatite and dolomite. The studied metal cations can activate quartz at a particular pH. It can be inferred from solution chemistry and zeta potential measurement that the influence of metal ions on the flotation of different minerals should be attributed to the adsorption of various hydrolysis species on the mineral surfaces. XPS analyses reveal that calcium ions can enhance the adsorption of anionic collector on apatite and quartz surfaces, and there are no apparent changes to be observed on the surface of dolomite in the absence and presence of calcium ions at a concentration of 2.5 × 10 −3 M, which was in good agreement with the micro-flotation results.

Abstract:The mid-low grade sedimentary phosphate ore, abundant in silicate and carbonate gangue minerals, exhibits a poor processability. It is conventionally enriched using high temperature flotation to remove silicate gangues with fatty acid as a collector. Cottonseed oil has been proved to be an efficient collector for achieving ambient temperature flotation of the sedimentary phosphate ore used in this study. Flotation kinetics was investigated to ascertain the excellent collecting performance of cottonseed oil, as compared with oleic acid, and the phosphate flotation fitted well with the first-order flotation model. Based on the analysis of flotation reagent effect on the direct flotation process using the response surface methodology (RSM), a closed circuit of direct-reverse flotation for stepwise removing silicate and carbonate gangues from the sedimentary phosphate ore was established. Consequently, a required high quality of phosphate concentrate containing 30.16% P 2 O 5 was obtained, with a recovery of 90.90%. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) of the flotation products confirmed that the majority of silicate and carbonate gangues were effectively removed from the concentrate products.

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In this study, the effects of various characteristics of artificial and natural magnetite concentrates on their pelletizing behaviors were elucidated through batch pelletizing experiments. The results showed that artificial magnetite concentrates exhibit higher hydrophilicity and lower electronegativity compared with natural magnetite concentrates. Additionally, scanning electron microscopy of magnetite particles demonstrated that the surface of artificial magnetite particles was rougher than that of natural magnetite particles, which causes the artificial magnetite to have a larger specific surface area compared with natural magnetite. Pelletizing experiments indicated that the compressive strength of artificial magnetite green pellets was higher than that of natural magnetite green pellets. However, the shock temperature of artificial magnetite green pellet was only 255°C, which is far lower than the requirements of industrial production. It was found that when the pelletizing raw materials were mixed to consist of 20% artificial magnetite and 80% natural magnetite, the ballability increased significantly.