Effects of n-hexadecane on pore wetting kinetics of porous carbon particles by 1H LF-NMR and its improvement on the flotation recovery

The wettability has an important effect on the floatability of carbon particles (low-rank coal and fly ash), including surface and pore wettability. The pore wettability of the porous carbon particles is a dynamic process and can further affect their surface wettability. In order to enhance the flotation performance of porous carbon particles, the roles of n-hexadecane on their pore wetting kinetics, chemical properties and surface hydrophobicity were studied by six classic flotation kinetic models, 1 H low-field nuclear magnetic resonance ( 1 H LF-NMR), fourier transform infrared spectroscopy (FTIR), contact angle and flotation experiments. 1 H LF-NMR could accurately characterize the volume of pure water and n-hexadecane in the pores of the particles. The wetting processes of total pores in the particles wetted by pure water and n-hexadecane both fitted the first-order model with rectangular distribution. However, the pore wetting degree and rate of the particles in n-hexadecane at the same time were all smaller than those in pure water. A larger number of methyl and methylene contained in n-hexadecane could physically adsorbed to the particles by the van der Waals forces, resulting in an increase of surface hydrophobicity. Therefore, the good flotation performance of the porous particles was achieved by non-polar liquid n-hexadecane. This work attempts to provide a new inspiration for the efficient flotation of porous carbon particles.