Mikhlin Yuri, Karacharov Anton, Vorobyev Sergey, Romanchenko Alexander, Likhatski Maxim, Antsiferova Svetlana, Markosyan Svetlana
Institute of Chemistry and Chemical Technology, Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences, Akademgorodok, 50/24, 660036 Krasnoyarsk, Russia.
Nanomaterials (Basel). 2020 Jul 12;10(7):1362. doi: 10.3390/nano10071362.
Surface nanobubbles at hydrophobic interfaces now attract much attention in various fields but their role in wetting-related phenomena is still unclear. Herein, we report the effect of a preliminary contact of "hot" solids with cold water previously proposed for generation of surface nanobubbles, on wettability of compact materials and flotation of particulate galena (PbS), sphalerite (ZnS), and Pb-Zn sulfide ore. Atomic force microscopy was applied to visualize the nanobubbles at galena crystals heated in air and contacted with cold water; X-ray photoelectron spectroscopy was used to characterize the surface composition of minerals. Contact angles measured with the sessile drop of cold water were found to increase when enhancing the support temperature from 0 to 80 °C for sphalerite and silica, and to pass a maximum at 40-60 °C for galena and pyrite (FeS) probably due to oxidation of sulfides. The temperature pretreatment depressed the recovery of sulfides in collectorless schemes and improved the potassium butyl xanthate-assisted flotation both for single minerals and Gorevskoye Pb-Zn ore. The results suggest that the surface nanobubbles prepared using the temperature difference promote flotation if minerals are rather hydrophobic and insignificantly oxidized, so the addition of collector and activator (for sphalerite) is necessary.
疏水界面处的表面纳米气泡目前在各个领域备受关注，但其在与润湿性相关现象中的作用仍不明确。在此，我们报道了先前提出的用于产生表面纳米气泡的“热”固体与冷水的初步接触对致密材料润湿性以及方铅矿（PbS）、闪锌矿（ZnS）和铅锌硫化矿浮选的影响。应用原子力显微镜观察在空气中加热并与冷水接触的方铅矿晶体上的纳米气泡；使用X射线光电子能谱表征矿物的表面成分。发现对于闪锌矿和二氧化硅，当将载体温度从0℃提高到80℃时，用冷水静滴测量的接触角增大，而对于方铅矿和黄铁矿（FeS），接触角在40 - 60℃时达到最大值，这可能是由于硫化物的氧化。温度预处理降低了无捕收剂体系中硫化物的回收率，但对于单一矿物和戈列夫斯科耶铅锌矿，均改善了丁基黄原酸钾辅助浮选。结果表明，如果矿物相当疏水且氧化程度不高，利用温差制备的表面纳米气泡会促进浮选，因此添加捕收剂和活化剂（用于闪锌矿）是必要的。
