Wettability of macerals from low rank bituminous

The specific wetting heats of different size vitrinite and inertinite in secondary deionized water were measured by micro-calorimeter,and surface wettability of malerals from low rank bituminous was analyzed.The results show that both vitrinite and inertinite from low rank bituminous are naturally wettable in water,the wetting phenomenon is spontaneous and the vitrinite is more hydrophilic than the inertinite.Based on the wetting heat measurements,proximate and ultimate analysis,defuse reflectance fourier-transformed infrared and X-ray photoelectron spectroscopy,it can be concluded that higher oxygen and hydroxyl content results in higher hydrophilicity of virtinite,which is related to low coalification degree and lower ash content of inertinite.The theoretical hydrophobicity of parent coal,vitrinite and inertinite is shown to decrease with particles size decreasing,especially of vitrinite.Wettability difference between vitrinite and inertinite is the foundation of floatation.Whereas,hydrophilicity difference between vitrinite and inertinite in coarser size fractions is much higher than the finer fractions i.e.,selective flotation of vitrinite and inertinite become more difficult at finer particle size.