磁场强度对煤泥重介旋流器分选效果影响研究

基于前期磁场强度对煤泥重介旋流器分选效果的影响规律,为了进一步研究高磁场强度对旋流器分选效果的影响,本文采用提出假设、试验验证与理论计算相结合的方法,在试验假设的前提下,通过对旋流器柱段安装空心圆环定性表征旋流器磁场作用区形成的磁铁矿粉“堆积层”,以空心圆环厚度表征不同磁场强度下形成的“堆积层”厚度,随着空心圆环厚度的增加,可获得精煤灰分逐渐降低,尾煤灰分基本不变,即分选精度提高的结论。试验结论与假设相反,反向验证了在旋流器内流场的高速剪切作用下,磁场作用区域内并未形成具有稳定厚度的磁铁矿粉“堆积层”。充分考虑影响磁团聚体形成与破坏的受力因素,通过公式推导得到磁场作用下磁团聚体粒度与磁场强度、介质悬浮液密度等参数的对应关系。结果表明,磁场强度超过一定值,磁团聚体粒度显著增大,导致介质悬浮液稳定性和流变性变差,进而造成旋流器分选效果变差。以上研究结果对于完善复合力场分选理论,指导煤泥重介旋流器磁调控策略具有意义。

Study on the Separation Effect of Slurry Dense Medium Cyclone Affected byMagnetic Field Intensity

In order to further study the effect of high magnetic field intensity on the separation efficiency of coal slime dense medium cyclone, on the basis of previous research results, this paper adopted the method of combining hypothesis, verification and theoretical calculation, and installed hollow cones with different thickness in the column section of the cyclone to qualitatively represent the "accumulation layer" formed under the hypothesis conditions. With the increasing thickness of hollow ring, the ash content of clean coal decreases gradually, and the ash content of tailings remains basically unchanged, that was, the separation accuracy was improved. The results showed that there was no magnetite powder deposited with stable thickness in the magnetic field area of the cyclone under the action of high-speed shear of fluid. From the point of force analysis and theoretical derivation, various factors which affecting the formation and destruction magnetic aggregates were fully considered, and the corresponding relationship between the particle size of magnetic aggregates and the parameters such as magnetic field intensity and suspension density were obtained. The results showed that when the magnetic field intensity exceeded a certain value, the particle size of magnetic agglomerate increased significantly, which resulting in poor stability and rheological change of medium suspension, and consequently deteriorating the separation effect of the cyclone. The research results were of great significance for improving the separation theory of composite force field and guiding the magnetic control strategy of slime dense medium cyclone.