Adhesion forces for water/oil droplet and bubble on coking coal surfaces with different roughness

• 作者: Chunyun Zhu Guosheng Li Yaowen Xing Xiahui Gui
• 来源期刊: 矿业科学技术学报（英文版）
• 年，卷（期）: 2021,（4）
• 页码范围: 681-687
• 页数: 7页
• 语种: 英文
• DOI: 10.3969/j.issn.2095-2686.2021.04.013

摘要

Surface roughness plays a significant role in floatability of coal. In the present paper, coking coal surface was polished by three different sandpapers and the surface properties were characterized by contact angle and roughness measurements. The effect of surface roughness on floatability was investigated by adhesion force measurement system for measuring interaction forces between droplets/bubbles and cok-ing coal surfaces with different roughness. The results showed that the contact angle decreased with increasing roughness yet the adhesion force between the water droplet and coal surface increased owing to the increased contact line and the appearance of line pinning. Maximum adhesion forces between water and surfaces were 111.70, 125.48, and 136.42 μN when the roughness was 0.23, 0.98, and 2.79 μm, respectively. In contrast, under a liquid environment, the adhesion forces between air bub-ble/oil droplet and coal surfaces were decreased with increasing roughness because of the restriction by water. Maximum adhesion forces of increasing roughness were 97.14, 42.76, and 17.86μN measured at interfaces between air bubble and coal surfaces and 169.48, 145.84, and 121.02μN between oil droplet and surfaces, respectively. Decreasing roughness could be beneficial to the spreading of oil droplets and the adhesion of bubbles which is conducive to flotation separation.