Kinetics of bubble interaction with low rank coal surface in the presence of adsorbed dodecane-oleic acid collector mixture

Abstract

ABSTRACT Bubble–particle interactions are crucial in the flotation process, and the influence of adsorbed chemicals on bubble-surface collisions/attachment is important to fully understand the role of mixed collector in low-rank coal (LRC) flotation. In this paper, the process of rising bubble attachment to LRC surface in the presence of adsorbed dodecane (D)-oleic acid (OA) collector mixture was studied using high-speed video camera and molecular-kinetic (MK) model. The results showed that collector adsorbed on LRC surface reduced the collision times, the time for stopping collision and reaching standstill. Mixed collector showed more obvious advantages than single collectors in accelerating bubble-surface collisions/attachment and increasing contact line length. Only when OA and OA-D were adsorbed, the wetting film between bubble and LRC surface broke and a stable three-phase contact was formed. The molecular displacement length of D-OA was smaller than that of single collectors, indicating the adsorption sites of bubbles on LRC surface treated with D-OA were more dense, and the higher displacement frequency of D-OA meant that the molecular displacement rate and TPCL expansion velocity was faster. D-OA enhanced the hydrophobicity of LRC surface through the synergistic effect between OA and D, which promoted the kinetics of bubble interaction with LRC surface.