一种新型浮选柱的数值模拟及性能研究

CFD Study for a Novel Multi-Stage Flotation Column

自主研制了一种新型多级规整填料浮选柱,应用计算流体力学软件FLUENT6.3.26进行数值模拟计算,对其内部的气液两相流动进行了考察,采用了欧拉-欧拉多相流模型,对气相的模拟采用单一气泡尺寸,液相湍流采用了标准k-ε模型,两相之间的动量传输仅考虑曳力作用。通过模拟,获得了不同实验条件下浮选柱内部的气液速度场分布、气含率分布等,对部分模拟结果进行了定量比较。结果表明随着气相流量的增大,浮选柱内部气含率增大,液体循环速度增大,从而气液之间混合更加充分,这对于提高浮选柱的分选效率和设备的放大有重要意义。在唐山钱家营开滦煤矿选煤厂进行了以其煤浆为原料的浮选性能的测试,在气体1.25 m3/h,进料0.05 L/h条件下20min停留时间获得了精煤灰分10.28%,尾煤灰分43.39%,精煤产率52.53%的指标,与该厂浮选精煤灰分10.58%相接近。

Novel multi-stage flotation column was developed independently in our lab and computational fluid dynamics software FLUENT6.3.26 was used for numerical simulation of gas-liquid two-phase flow. Euler-Euler muhiphase flow model was used to simulate gas phase with single gas bubble size. A standard k-ε turbulence model was used to describe two phases in the simulations, considering the drag force for interphasc momentum transfer only. The liquid velocities, axial liquid velocities and gas holdup distribu- tion in the different radial positions were obtained through the simulations. It was shown that increasing the gas velocity would improve the gas holdup and liquid circulation rate, which means the more suffi- ciently gas and liquid were mixed, the better effect of flotation would be. It is significant for improving the separation efficiency in the column and the scale-up of the column. Performance of multi-stage loop packed flotation column at different conditions was tested with coal slurry in Qianjiaying Kailuan Mining Company. Under gas velocity of 1.25 m3/h and feed of 0.05 L/h, with residence time of 20 min, coal ash was 10.28% , tail ash of 43.39% , clean coal yield of52.53%. It was close to coal ash of 10.58% in this company.