Effect of Dodecane-Oleic Acid Collector Mixture on the Evolution of Wetting Film between Air Bubble and Low-Rank Coal

Abstract

The wetting film evolution process is essential for flotation, especially in bubble–particle attachment. A mixed collector has been proved effective in promoting flotation. In this paper, the effect of a mixed collector (MC) composed by n-dodecane (D) and oleic acid (OA) on wetting film evolution was investigated using the extended Derjagin–Landau–Verwey–Overbeek (EDLVO) theory, the Stefan–Reynolds model, induction time, and zeta potential measurement. The hydrophobic force constant between bubble and coal treated by different collectors was analyzed. The results showed that MC was superior in reducing the induction time and increasing the zeta potential. When bubbles interacted with coal treated by MC, they had relatively low interaction energy, high critical film thickness, and high drainage rate. The order of hydrophobic force constant was no reagent < D < OA < MC. It indicated that the hydrophobic interaction between bubbles and coal particles treated by MC was the strongest because of the synergistic effect of D and OA.

Detachment Force of Air Bubbles Detached from Low-Rank Coal Surface in the Presence of Adsorbed Oleic Acid–Dodecane Collector Mixture

“…Thus, it can be inferred that the improvement effect of the three collectors on the surface hydrophobicity of low-rank coal is OA−D > OA > D. This deduction is consistent with the contact angle measurement and flotation results reported in previous studies. 31,32 Low-rank coal surface is rich in oxygen functional groups. D is a nonpolar collector and can adsorb on the hydrophobic area.…”

“…The mixed collector was composed of dodecane and oleic acid in the mass proportion of 4:1. When the mass ratio of OA in the mixed collector was changed from 0.2 to 0.3, the interfacial tension between oil and water decreased by about 1.5 mN/m. , Considering that the price of OA was higher than that of common oil collectors, we selected 0.2 as the proportion of OA in the mixed collector.…”

New Insight into Temperature Effects on Low-Rank Coal Flotation Using Diesel as a Collector

“…Some scholars focus on the new high-efficiency collectors, mainly focusing on the research of polar collectors and compound collectors. The results show that the polar collector can cover the oxygen-containing sites on the surface of LRC and improve the surface hydrophobicity of LRC, so the clean coal yield of flotation is improved. − In addition, the synergistic effect of polar and nonpolar components in the compound collector further strengthens the flotation.…”