Abstract:
The contact angles of five types of fine ashes with different particle size distributions produced by the gasification of opposed multi-burner coal water slurry were measured by Washburn capillary tube, with the reference solution (
n- hexane) for measuring the effective radius. X-ray diffraction and Fourier infrared spectrometer were used to determine the XRD pattern and infrared spectrum of the fine ashes, respectively. The surface groups, crystal mass fraction and crystallinity of inorganic minerals were analyzed in order to determine the influence of physical and chemical properties on their wettability. The results show that the contact angle of the fine ashes decreases as the particle size increases. However, the decreasing trend is not linear with the particle size. In addition, the functional surface groups including Si−O−Si and −OH and inorganic minerals including SiO
2 are found to determine the wetting characteristics of the fine ash particles in addition to particle size. A good linearity was determined between the peak area of the Si−O−Si and −OH groups in the infrared spectrum and the contact angle of fine ashes. The wetting contact angle decreases with the increase of peak areas of the functional groups, suggesting that the surface area of Si−O−Si and −OH in the infrared spectrum can be used as a quantitative index to characterize the wettability of fine ashes produced by coal gasification.