Lignite powder briquetting with binder and adsorption model of binder on the coal surface

ABSTRACT The addition of different binders can improve the mechanical strength of briquette for the lignite powder. The changes of lignite in wettability, functional groups and surface electrical properties were analyzed after briquetting. The model of the interaction between the binder and coal particle was studied. The results revealed that starch and polyvinyl alcohol binders could make the compressive and drop strength of lignite briquette strong. When the potential value decreased, it was beneficial to the briquetting process. The Fourier transform infrared spectra (FTIR) analysis showed that functional groups of binder adsorbed the oxygen-containing functional groups of coal. After the binder interacted with the pulverized coal, the molecules in the binder were adsorbed on the surface of coal, which changed the hydrophobicity of the pulverized coal. An adsorption model was proposed as follows: The first was the various types of hydrogen bonds between the hydroxyl terminus of binder and the carboxyl group or hydroxyl group on the surface of coal. The second was the generation of hydrogen bonds among the binder molecules. The greater hydrogen bonding was, the higher the strength of briquette was.