Separation Research Of Different Particle Size Coal In Vibrated Fluidized Bed

A long term process of coal washing is demanded by the increasingly serious environmental problems, whereas the current situation of water shortage restricts the development of traditional wet coal preparation. Therefore, a more efficient dry separation method is in urgent need. Air dense medium fluidized bed coal preparation technology has been proved to efficiently grade coal separation of +6 mm, with E value of 0.05-0.08. But for the grade of fine coal whose particle size is less than 6 mm, the traditional fluidized bed cannot meet the separation requirements. It has been pointed out that the vibration energy introduced into fluidized bed can significantly improve the fluidized bed stability and the effect of fine coal separation.This thesis build the intermittent separation system using a vibrated fluidized bed(VFB). The fluidization characteristics of fluidized bed is researched by fluidization curves in different vibration intensity and medium solids. Researches pointed out that compared with ordinary fluidization bed, VFB has advantages in decreasing minimum fluidization velocity and fluidized state of pressure fluctuations, and enhancing the stability of VFB. Magnetic mineral powders mixed with quartz sands are used as the heavy medium. With the increase of the quartz sands ratio, the minimum fluidization velocity decreases.Based on single factor experiment of 6-3mm fine coal, the three factors and three levels orthogonal experiment of 6-3mm, 3-2mm, 2-1mm, 1-0.5mm fine coal is carried on by the BoxBehnken response surface method using the Design-Expert software. Researches shows that the sorting effect gradually decreases with the decline of grain size. For 6-3 mm graded coal, in the case of the concentration ash content is lower than 4.65%, the combustible recovery rate is as high as 86%. For 1-0.5 mm coal grade, in the case of the ash content lower than 18%, the combustible recovery ratio can be made at around 70%.This paper researches the separation effect of mixed coal grains of four particle size coal in same quality in VFB. The result shows that the separation effect for 3-2 mm, 2-1 mm, 1-0.5 mm three grades is better than that of selected grading, which means that the existence of 6-3 mm graded coal can improve the VFB separation effect to 3-0.5 mm graded coal.By mixing magnet mineral powders with quantitative quartz sands as mixing heavy medium solids, this paper studies the separation effect of 2-1 mm graded coal. The results shows the best sorting effect happens when the magnet mineral powder and quartz sand quality ratio is 2:0.3, in this case, the ash content is 8.47%, combustible recovery rate is 91.86%. Therefore the VFB fine coal separation effect can be improved by mixing magnet mineral powders with quantitative quartz sands. By the separation and sink-float experiment in mixing heavy medium solids VFB, the result show that the E values of four coal grades(6-3 mm, 3-2 mm, 2-1 mm, 1-0.5 mm) separation in the vibration fluidized bed are respectively 0.090, 0.127, 0.137,0.270 g/cm3.