Study on the mechanism of adsorption and hydrophobic modification of glycerol monooleate/kerosene mixed collector on low-rank coal surface

A new collector (GK) consisting of GMO (glycerol monooleate)/kerosene was developed to address the problem that low-rank coal is difficult to be recovered by flotation with conventional non-polar oil collector. The flotation test proved that GK collector has excellent flotation performance for low-rank coal (combustible recovery rate close to 90 % while the ash content of clean coal is about 6 %). The contact angle, infiltration time, wetting heat and XPS analysis demonstrated that GK collector can significantly improve the hydrophobicity of low-rank coal, resulting in a great improvement of flotation efficiency. Molecular dynamics simulation shows that the hydrophilic head of GMO molecules can adsorb with low-rank coal directly through hydrogen bonding or indirectly through water bridges. The presence of GMO molecules in GK collector can increase the overall interaction strength of collector oil droplet with low-rank coal surface by more than half. A schematic diagram of collector adsorption on the surface of low-rank coal is drawn, which gives a complete overview of the stacking and hydrogen bonding connection modes at the molecular level of low-rank coal, water, GMO and kerosene adsorbed at the interface. The adsorption mechanism of this mixed collector on the surface of low-rank coal was clarified.