Desulfurization Effect of High-Sulfur Weibei Coal of Assisted by Microwave Irradiation and Ultrasonic Wave

Abstract

The desulfurization process of high-sulfur coal in Weibei was studied by flotation pretreatment and microwave combined with ultrasonic wave and oxidants. Through the single factor experiment which took Chenghe coal as the sample, the optimum conditions of this process had been concluded as follows: microwave power was 250 W, microwave time was 15 min, ultrasonic temperature was 60 °C, ultrasonic time was 30 min, coal slurry concentration was 0.083 g/ml, coal particle size was less than 0.074 mm, the dosage of agents was 8 mL/g, the radio of acetic acid and hydrogen peroxide was 1:3. After fractional release pretreatment, the sulfur reduction of Chenghe coal could reached to 53.10%. As to Hancheng coal, the value was 46.41%. By analyzing XRD and XPS spectra, it showed that most inorganic sulfur were removed by flotation pretreatment, and under the function of microwave combined with ultrasonic wave and oxidants, a part of organic sulfur was removed, such as mercaptan, sulfoxide and thiophene. However, as for sulfone, the removal effect was not obvious. The results proved that the experimental method could remove most of inorganic sulfur and part of the organic sulfur and significantly reduce the coal ash.