Experimental Research And Flow Field Analysis On Wide-Size-Fraction Coal Slime Flotation Machine

Nowadays, facing the needs of energy saving, efficiency improvement, environment-protection and other aspects, how to work out a reasonable and effective solution to the problem of coal slimes mixing flotation has become the priority among priorities of the coal preparation plants. Due to the fact that there exist a gap of effective separation of particle sizes between gravity concentrate and flotation, namely, with the decrease of particle sizes in the gravity concentrate process, separation efficiency declines, whereas with the increase of participle sizes in flotation process, separation efficiency gradually declines. When the particle size of the coarse slime ranges near the junction of the effective separation boundaries in gravity concentrate and flotation, the separation efficiency reaches to the lowest level. Therefore, the key point to the progress of coal preparation technology and the economic benefits improvement of coal preparation plant is whether the coarse slime is effectively sorted.By preliminary study of expanding the upper limit of particle size in coal flotation, this research group proved that the technical objective of making the limit1mm is achievable. And according to different hydromechanics conditions needed in coarse particle and fine particle, the group designed a wide-size-fraction coal slimes flotation machine which can be used in both fine particle conventional flotation and coarse particle fluidized flotation. Based on the flow field numerical simulation of liquid single-phase in the flotation machine and the analysis of the fluid velocity and turbulence intensity of the flotation machine, this paper verified that the wide-size-fraction coal slimes flotation machine is able to provide the hydromechanics environment for the flotation of both coarse particle minerals and fine particle minerals separately. The new designed testing system was employed to the flotation experiment on0-1mm coal slime in Tunlan Coal Preparation Plant. The results show that, the ash content of tailings with-lmm can reach up to55percent and the quantitative index of flotation concentrate and combustible mass recovery rate of0.125-1mm wide-size-fraction slime can reach up to91.05percent and84.81percent respectively, which demonstrates that this wide-size-fraction coal flotation machine can be used to separate-1mm level of coal slime effectively. After that, in order to test the effect on the flotation results when reducing the amount of the internal circulation of the machine and the ejection in the tailing outlet, the number of circulation holes was changed into3and the tailing outlet was placed in the flank of the machine instead of the center of the bottom. The numerical simulation of the new structure showed that the changed flotation machine can also provide the hydrodynamic environment for both coarse and fine mineral flotation separately. Flotation experiment showed that after changing the place of the tailing outlet of the flotation machine, the ash content can reach up to63percent and the quantitative index of flotation concentrate and combustible mass recovery rate of0.125-1mm wide-size-fraction slime can reach up to92.95percent and91.51percent respectively, which manifested that the flotation is rather effective. However, the defect was that the ash content of each size fraction concentrate also rose considerably, so the structure still needs to be further optimized. Changing the number of circulation holes had a small effect on the flotation results; it mainly improved the flotation of fine particle mineral.