Use of ultrasonic emulsification in oil agglomeration for coal cleaning

Abstract Emulsification is one of the most important stages in coal cleaning by using oil agglomeration. Reduction in size of oil droplets and increase in total surface area provided by emulsification result in coverage of entire coal surface with oil, thereby reducing the oil dosage and affecting rapid agglomeration. Ultrasonic emulsification which has been used recently in many sectors such as pharmaceutical, cosmetic, food, chemical industries may be a beneficial and promising operation in oil agglomeration of coal. In the present study, an oxidized fine coal with high ash and pyritic sulfur content was cleaned by oil agglomeration process after ultrasonic emulsification and the effects of power level and time of ultrasonic treatment on the performance of the agglomeration process were determined. Ash and pyritic sulfur rejections that was found to be 50.38% and 85.28%, respectively, at agglomeration test without ultrasonic emulsification was increased to maximally 56.89% and 88.69% by using ultrasonic emulsification before agglomeration. While increase in power of ultrasonic treatment did not affect ash and pyritic sulfur removals considerably, ultrasonic treatment time had positive affect at higher power levels. Contrary to expectations, ultrasonic emulsification affected the combustible recovery and separation efficiencies adversely.