Flotation Performances of Different Size Fractions of Low-Rank Coal in Air- and Oily-Bubble Processes

Abstract

ABSTRACTXPS results of different size fractions indicated that the content of oxygen-containing functional groups on the 0.500–0.250 mm and -0.074 mm size-fraction surfaces are much higher than that of other size fractions. Furthermore, both the 0.500–0.250 mm and -0.074 mm size fractions account for 63.35% of the raw coal. Therefore, the low-rank coal is extremely difficult to float in an air-bubble-flotation process. In order to efficiently float low-rank coal, a novel flotation process is proposed in this article that was named the oily-bubble-flotation process. Induction Timer 2015 was also used to compare the mineralization degree of different size particles between air and oily bubbles. The flotation results of low-rank coal in air- and oily-bubble processes indicated that the combustible matter recovery in the oily-bubble-flotation process for low-rank coal increased with increasing the diesel oil dosage and decreases in the particle-size fraction, especially for the -0.074 mm size fraction. Meanwhile, the oily-bubble flotation can obtain a better selectivity of finer particles flotation, which can effectively reduce the occurrence of entrainment. Therefore, the flotation performance of different size fractions of Da Liuta low-rank coal may be enhanced by oily-bubble flotation.