Effects of High-Power Ultrasonic Treatment on the Slurryability of Coals

To improve slurryability, high power ultrasonic energy was used to treat coal slurry. The influence of power on the slurryability of raw coals and on the maximum hydro-content (MHC) was investigated by measuring the apparent viscosity before and after treatment. The experimental results show that the effect of treatment on sluryability is different for different rank coals under the same treatment conditions. The coals metamorphosed to lower degree are more sensitive to the ultrasonic treatment. The apparent viscosity of slurries from coal metamorphosed to medium degree clearly decreases after the ultrasonic treatment. The ultrasonic treatment makes MHC decrease, which improves the slurryability. For Shenmu or Hebi coal slurry after 3 min. treatment the maximum fixed-viscosity concentration is increased by about 0.4% and 0.3%, respectively, when the ultrasonic power is 100 W. The maximum fixed-viscosity concentration increased 2.4% and 1.7%, respectively, when the ultrasonic power was 300 W, but it decreased by about 0.4% and 0.7%, respectively, when the power was 500 W.