Influence of frother dosage on the interaction between low rank coal particles and bubbles

The stable adhesion between particles and bubbles plays a decisive role in whether particles can be successfully trapped by bubbles in flotation process.The change of interaction force between bubbles modified by frother and low rank coal particles affects their adhesion behavior The influence mechanism of frother on the interaction between low-rank coal and bubbles is not clear yet.Non caking coal from Inner Mongolia and air bubbles modified by frothers (2-Octanol) are used as research objects.Atomic force microscopy (AFM) is used to probe the interaction force between low-rank coal and bubbles treated with different concentrations of frother.Molecular dynamics simulation is used to reveal the microscopic action mechanism of frother at the gas-liquid interface.Finally,by directly measuring the adhesion efficiency between particles and bubbles,the measurement results of the interforce between particles and bubbles at micro and nano scales are directly verified on a macro scale.The results show that the “jump contact” disappeared gradually with the increase of foaming agent concentration.The interaction force between low-rank coal particles and bubbles modified with frother also changes obviously.With the increase of the concentration of frother,the adhesion force between particles and bubbles weakens significantly,and even appears a tendency to disappear.The adhesion efficiency between particles and bubbles of low rank coal decreases accordingly.Molecular dynamics simulation showes that the hydrogen bond formed between the hydrophilic group (—OH)of frother and water molecules bound the diffusion movement of water molecules on the surface of bubbles when frother was adsorbed at the gas-liquid interface.With the increase of the number of frother molecules,the binding effect became more intense,thus greatly reducing the hydrophobicity of the surface of bubbles.Therefore,after the modification of bubble surface with frother,the reduction of hydrophobicity on bubble surface weakens the adhesion force between low-rank coal particles and bubbles,and then affects the adhesion behavior between them.