Intensification mechanism of oxidized coal flotation by using oxygen-containing collector α-furanacrylic acid

A traditional hydrocarbon collector dodecane and an oxygen-containing collector alpha-furanacrylic acid were selected for oxidized coal flotation in the present study, respectively. The changes of the surface functional groups and zeta potential of oxidized coal were measured before and after alpha-furanacrylic acid absorption and the electro-negativity of functional groups in a-furanacrylic acid was calculated to indicate its absorption mechanism on oxidized surface. Surface free energy and interfacial interaction energy were calculated to identify the interaction mechanism between coal and alpha-furanacrylic acid from the perspective of thermodynamics. Results show that 53.80% flotation yield with 14.03% ash content was obtained when 7000 g/t dodecane was used. In contrast, 69.17% yield with 11.98% ash content could be obtained only using 931 g/t a-furanacrylic acid. The high flotation recovery was attributed to the hydrogen bonding function between a-furanacrylic acid ( COOH and oxygen-containing five-memered rings) and oxidized coal surface. The interfacial interaction energy is 21.20 mN,m(-1) for coal-water-alpha-furylacrylic acid system while 23.09 mN.m(-1) for coal-water-dodecane system. A repulsive hydration force was found between oxidized coal and a-furylacrylic acid via water phase. alpha-Furanacrylic acid could not form hydrogen bond directly with the oxygen-containing functional groups on coal surface. Instead, the water molecules in hydration film may act as the bridging role of hydrogen bond for alpha-furanacrylic add absorption on oxidized coal surface. (C) 2016 Elsevier B.V. All rights reserved.