Efficiency and mechanism analysis of the flotation of anthracite coal using soybean oil as an alternative sustainable collector

Vegetable oils are sustainable and used as raw material in many industrial areas. For coal flotation cleaning industry, hydrocarbon oils are always required as the flotation collector. If the vegetable oils can replace the hydrocarbon oils in coal flotation cleaning, the coal preparation industry will become sustainable. The aim of this paper was to study the efficiency and mechanism of anthracite coal flotation using soybean oil as the collector to replace the kerosene. The flotation behavior of fine coal using soybean oil as the collector was better than that using kerosene as the collector. Fourier transform infrared spectroscopy (FTIR) results indicated soybean oil contained plenty of fatty acids and carbonyl functional groups which might be bonded with coal surface through hydrogen bonding between these similar hydrophilic functional groups. Therefore, coal hydrophobicity using soybean oil as the collector was higher than that using kerosene as the collector. Additionally, focused beam reflectance measurement (FBRM) results indicated the droplet size of kerosene was much larger than that of soybean oil at the same stirring intensity. A better dispersion of oil collector in the flotation pulp enhanced the collision and attachment efficiency of coal-oil droplet. Therefore, the surface hydrophobicity and flotation recovery of fine coal were both improved as well as the coal flotation becomes sustainable by using soybean oil as an alternative sustainable collector.