Effects of energy consumption on the separation performance of fine coal flotation

To explore the laws of energy consumption in the fine coal flotation process, an energy consumption test system was established. In this investigation, it was discovered that fine coal with high ash content from Kailuan mine in China is difficult to float. The energy input in coal flotation process was changed by adjusting the shaft power and flotation time. A flotation rate test was conducted under different shaft speed conditions, and the characteristics of the flotation products with varying energy consumption were analyzed. The results showed that the floatability of the floating material decreased with the energy consumption increased. With the increase of energy consumption, the rate of increased yield of fractions is from higher to lower as following: 0.043–0.074 mm, 0.074–0.124 mm, − 0.043 mm, 0.124–0.246 mm, 0.246–0.495 mm, + 0.495 mm. Higher combustible matter recovery was achieved under high shaft speed conditions within the same flotation time. However, high energy input may increase the pollution of high-ash fine mud in the concentrate. The coarse intergrowth particles, such as coal and rocks were non-liberated and part of the micro-fine-grained coal particles, could be recovered by high energy input. For example, 18.74% concentrate yield was obtained for 1.5–1.6 g/cm3 intergrowth particles at 144 J energy input at the later stage of flotation process while the shaft speed is 1500 r/min.