Study on the influence of coal surface roughness on contact angle and surface energy

ZHANG Jian; XU Bo; WEI Jianping; ZHANG Pengyan; CAI Maolin; ZHANG Kaixuan

doi:10.16186/j.cnki.1673-9787.2021080073

Abstract：In order to effectively control mine dust,improve the working environment,and ensure the safety of operation,the research focused on the surface roughness of coal.Hami lignite,Laogongyingzi lignite,Anyang coking coal,and Zhaogu anthracite were selected as research subjects.The surface roughness of coal was mea-sured using a non-contact method after being polished with different mesh sandpapers.The contact angle of different roughness of coal was measured by the seat-drop method after being wetted by deionized water and glycerol.The surface energy of coal with different surface roughness was calculated using the OWRK method.This study investigated the impact of coal surface roughness on contact angle and surface energy.The results showed that:with the increase of surface roughness,the contact angle of Hami lignite,Laogongyingzi lignite and Zhaogu anthracite gradually decreased,while the surface energy of coal increased.In contrast,the contact angle of Anyang coking coal increased,and its surface energy decreased.Lignite is hydrophilic,coking coal is hydrophobic,and anthracite is weakly hydrophilic.The metamorphic degree of coal affects both the trend and range of contact angle change and the nature of surface energy.The surface energy and wettability of the four coal samples exhibited similar trends with surface roughness.The results and patterns of how surface rough-ness affects coal wettability could be analyzed from the perspective of surface energy.The surface energy was negatively correlated with the contact angle,and the contact angle of the four coal samples decreased with the increase of surface energy.