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

ABSTRACT

XPS 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.

KEYWORDS:

• Oily-bubble flotation
• air-bubble flotation
• induction time
• size fraction
• low-rank coal
• XPS

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 51574235), the Project for Graduate Research and Innovation in Universities of Jiangsu, China (Grant No. KYLX15_1413), and the China Scholarship Council.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 51574235), the Project for Graduate Research and Innovation in Universities of Jiangsu, China (Grant No. KYLX15_1413), and the China Scholarship Council.