Zhang Na, Chen Xumeng
School of Chemical Engineering, The University of Queensland, St Lucia, Brisbane, QLD4072, Australia.
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China.
ACS Omega. 2023 Sep 7;8(37):33564-33571. doi: 10.1021/acsomega.3c03647. eCollection 2023 Sep 19.
Kaolinite and quartz are the common gangue minerals found in raw coal; however, their effects on stability of coal froths and subsequent settling of coal flotation products have not been investigated. In this study, in the coal froths batch settling tests, the amount of froth floating on top of water was 275, 325, 355, and 405 mL for coal concentrates generated with 0, 20, 40, and 60 wt % kaolin Q38, respectively, while that was almost the same (300-306 mL) for coal froth concentrates generated with 0, 20, 40, and 60 wt % quartz added in flotation, respectively, which turned out that the kaolinite could increase the stability of coal froth, while quartz could not. To investigate the mechanism, oscillatory rheology and scanning electron microscopy (SEM) were applied. The results of the oscillatory rheology suggested that the structural strength in coal froth was strengthened with the addition of kaolinite. In addition, images of Plateau borders by SEM illustrated that the addition of kaolinite in flotation increased the size of Plateau borders and generated network structures in the Plateau borders. However, as a comparison, the addition of quartz did not cause an obvious change for the oscillatory rheology and SEM results of coal froth. Based on the results, it can be concluded that network structures were generated in the Plateau border of coal froth with the addition of kaolinite, which increased its structural strength and retarded the drainage in froth. As a result, the stability of the coal froth increased.
高岭土和石英是原煤中常见的脉石矿物；然而，它们对煤泡沫稳定性及后续煤浮选产品沉降的影响尚未得到研究。在本研究中，在煤泡沫间歇沉降试验中，分别添加0、20、40和60 wt%高岭土Q38所产生的煤精矿，浮在水面上的泡沫量分别为275、325、355和405 mL，而在浮选过程中分别添加0、20、40和60 wt%石英所产生的煤泡沫精矿的泡沫量几乎相同（300 - 306 mL），结果表明高岭土会增加煤泡沫的稳定性，而石英则不会。为研究其机理，采用了振荡流变学和扫描电子显微镜（SEM）。振荡流变学结果表明，添加高岭土会增强煤泡沫的结构强度。此外，SEM拍摄的Plateau边界图像表明，浮选过程中添加高岭土会增加Plateau边界的尺寸，并在Plateau边界中产生网络结构。然而，作为对比，添加石英对煤泡沫的振荡流变学和SEM结果没有引起明显变化。基于这些结果，可以得出结论，添加高岭土会在煤泡沫的Plateau边界中产生网络结构，这增加了其结构强度并阻碍了泡沫中的排水。结果，煤泡沫的稳定性增加。
