Rongdong Deng,Yi Wang,Wenting Duan,Dingquan Xing,Yuan Hu
Smithsonite is a common oxidized zinc ore , and its recovery has gained increasing attention to meet the high demand for zinc. Current methods to concentrate oxidized zinc ores are through sulfidation flotation or “sulfidation + metal + xanthate” flotation. However, such techniques are not sufficiently efficient for treating smithsonite. In this study, Pb(NO 3 ) 2 was used to pre-treat smithsonite as a crystallization inducer, and the mechanism of lead modification was studied through micro-flotation tests, adsorption measurements, contact angle measurements, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and TOF-SIMS analysis. The micro-flotation test results showed that the recovery of smithsonite after Pb 2+ pre-treatment increased from 80.3% to 85.3%. The comprehensive results of adsorption experiments, contact angle measurements, XRD and SEM analysis indicated that Pb 2+ adsorbed on the smithsonite surface and transformed portion of smithsonite into cerussite, increasing the active sites on the mineral surface for adsorption of S ions . The newly formed PbS after sulfidation had an effect of induced crystallization on subsequently formed PbS, increasing PbS species and making the surface more effective for xanthate flotation. ToF-SIMS was used to visualize the 3D distribution of Pb 2+ and S 2- adsorption, and it further proved that pre-treatment with Pb(NO 3 ) 2 enhanced the sulfidation process of smithsonite.
Yanfei Chen,Guofan Zhang,Mengtao Wang,Qing Shi,Dezhi Liu,Qi Li
Sulphidisation xanthate flotation is a common process in dealing with zinc oxide minerals and sulphidisation is the key procedure in the zinc mineral recovery. In this study, the effect of Ca 2+ on the sulphidisation flotation of smithsonite was investigated by flotation tests. The results show that the presence of Ca 2+ impairs the sulphidisation flotation of smithsonite. Adsorption studies and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) analysis illustrate that at pH 9.5, where the sulphidisation process is routinely performed, the positively charged Ca(OH) 2(s) , Ca(OH) 2(s) , and CaOH + produced due to hydrolysis and precipitation of Ca 2+ will preferentially adsorb onto smithsonite surface, preventing the adsorption of sulfur ions. Thus, the insufficient sulphidisation on smithsonite surface cannot promote the mineral flotation performance. Interestingly, sodium carbonate can eliminate adverse effect of Ca 2+ by charge reversal. For its reactivity with Ca 2+ , the formation of negatively charged calcium carbonate ceases the adsorption of calcium onto smithsonite surface as a consequence of electrostatic repulsion. As thus, the sulphidisation flotation of smithsonite is regained.
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