Study of Prevention of Dispersion of Coal Dust in the Wind

Dispersion phenomena of coal dust and methods to prevent dispersion were studied in a wind tunnel. The critical friction velocity had its minimum value when the particle diameter of coal dust was around 180 μm. At wind speeds between 10 and 15 m/s, the dispersing quantity of coal dust had its maximum value when the particle diameter of coal dust was between 200 and 600 μm. The dispersion quantity of less dispersable fine powder increased when it was mixed with more dispersable powder or when coarse grain was located on the surface of the powder bed, and the quantity had its maximum value at a certain ratio of the mixture. The addition of water to coal dust was effective for preventing dispersion, especially at low wind speed and short elapsed time after its addition. Non-dispersion chemicals completely prevented dispersion. Fundamental data to determine the desirable amount and concentration of the chemicals for practical use were obtained.