Ultrasonic assisted cleaning of high sulphur Indian coals in water and mixed alkali

Ultrasonic-assisted coal beneficiation: A review.

Feasibility studies of de-sulfurization and de-ashing of low grade medium to high sulfur coals by low energy ultrasonication

Increasing coal quality by oil agglomeration after ultrasonic treatment

Producing low-ash coal by microwave and ultrasonication pretreatment followed by solvent extraction of coal

The present work investigates utilization of ultrasound in reagent-based coal de-ashing and de-sulfurization. The coal under study was received from Girald mine, Rajasthan, India. Three different ultrasonic frequencies (25 kHz, Dual (58/192 kHz) and 430 kHz) and three reagents (HCl, HNO 3 and H 2 O 2 ) were used. The study employed a Taguchi fractional-factorial L 27 DOE. Experimental data were used to derive an empirical model for the prediction of total sulfur removal. The model incorporates cavitational intensity, reagent concentration, sonication time, coal particle size and coal concentration as key parameters. Effects of above factors on reagent-based ultrasonic coal-desulfurization are presented here. An optimum set of process parameters are identified and validated. Larger-scale trial with high-ash and high-sulfur coals is strongly recommended.

T.N. Chintala

Papers

Feasibility of using ultrasound-assisted process for sulfur and ash removal from coal