Further exploring on aqueous chemistry of micron-sized lignite particles in lignite water slurry: Effects of humics adsorption

The aqueous chemistry of micron-sized lignite particles has essential influences on the dispersion stability of water-lignite slurry. In this work, the adsorption behaviors of dissolved Mimics on lignite surface in lignite-water slurry were studied through batch adsorption experiments. The influences of adsorbed humics on the surface properties, particle size distribution and dispersion stability of lignite particles in water-lignite slurry were examined by advanced analysis techniques, EDLVO theory and settlement tests. The adsorption results indicate that the adsorption capacity of humics on lignite increases from 4.11 mg.g(-1) to 8.25 mg.g(-1) with the humics concentration increasing from 100 mg.L-1 to 200 mg.L-1. The adsorption process can be well described by the pseudo-second order kinetic model. The adsorbed humics significantly improves the hydrophilicity and electronegativity of lignite surface and reduces the apparent particle size of lignite. The EDLVO calculation and settlement tests reveal that the total interaction energy of the humics-adsorbed lignite particles at 18 nm of separation distance is enhanced from 0.85 x 10(-17) J to 1.45 x 10(-17) J with the initial humics concentration increasing from 100 mg.L-1 to 200 mg.L-1. The dispersion stability of micron-sized lignite particles is improved with humics adsorption on lignite surface.