Effect of Chloride Salt Ions onto Coal Flotation based on Contact Angle and Bubble-Particle Attachment Time

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Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi, vol.24, no.71, pp.553-562, 2022 (Peer-Reviewed Journal) identifier


This study was aimed to reveal the effect of K+, Na+, Ca2+, and Mg2+ ions on the bubble-particle interactions of high-rank coal with contact angle and bubble-particle attachment time studies. The results for the contact angle experiments indicated that the contact angle of the coal, which was 62° in the absence of ions, increased slightly in the presence of mono- and divalent ions and reached a maximum (67°) in the presence of 1∙10-1 mol/dm3 Mg2+, and the effect of K+ ions on the contact angle was minimal. Furthermore, the results for the bubble-particle attachment time experiments showed that the bubble-particle attachment time of coal, which was measured as 4.5 ms in the absence of ions, decreased as a function of ion concentration from 1∙10-2 mol/dm3 to 1 mol/dm3. While the bubble particle attachment times of coal particles in the presence of K+/Na+ and Ca2+/Mg2+ at low concentrations were around 2-3 ms and 1-2 ms, respectively, the increase in the concentration slightly changed the attachment time which decreased to less than 1 ms except for K+ ions. Overall, it can be concluded from this study that the effect of these dissolved ions in water was more prominent on the bubble-particle attachment time of the coal particles rather than the contact angle which showed no significant change. Also, the specific ion effect was determined as “Mg2+ > Ca2+ > Na+ > K+” in terms of the bubble-particle interactions in the presence of these ions. Keywords: Chloride Salt Ions, Coal, Flotation, Bubble-Particle Attachment Time, Contact Angle