Flotation intensification of the coal slime using a new compound collector and the interaction mechanism between the reagent and coal surface

Flotation reagents in particular the flotation collector plays a significant role in the cleaning efficiency of coal slimes in the coal preparation and utilization industry. A new collector (NC) was used to achieve the efficient cleaning of coal slimes. Comparing with the conventional flotation collector of diesel oil (DO), the higher yields and lower ash contents of clean coal with the higher combustible material recoveries could be obtained using the NC in flotation. The optimum NC dosage of 500 g/t was acquired through the unit flotation tests. Fourier transform infrared spectroscopy (FTIR) and contact angle measurement were used to study the interaction mechanism between the flotation collector and coal surface. The results indicated that the stronger electron-attracting ability of the ester groups than that of the carbon-carbon double bond resulted in the more stable interaction between the NC and coal surface than that between the DO and coal surface. The contact angle of the coal slime wetting with the NC of 67.1° was larger than that with the DO of 62.6°, suggesting the stronger hydrophobicity of the coal slime with the NC than that with the DO. The chemical composition analysis results suggest that the NC belongs to a compound flotation reagent, which provides an alternative high-efficient collector for coal flotation industry.