Abstract
The effect of the pH of the disperse medium on the deashing of coal was investigated in the oil agglomeration process. A coal-water slurry used in the experiment was prepared by suspending ground coal in water as the disperse medium the pH of which was adjusted to 2, 4, 7, 10 and 12. A-class heavy oil was used as the bridging liquid.
The zeta potential ζ of the coal particle was negative at any pH condition of the disperse medium and |ζ| became the largest value at pH=12. The dispersion of coal particles in the slurry improved with increase in the value of |ζ|. The deashing efficiency of coal by oil agglomeration increased with the dispersibility of coal particles and attained the highest value at pH=12.
