叶片式旋转涡流场中多级配矿物颗粒群分级机制研究

The subject proposed a new device and method in order to improve classification efficiency of mineral particles for low classification efficiency at present dressing plant. Spiral sieving classification despited using a classification principle alone, which combined with advantages of hydraulic classification and sieving in eddy current field. Spiral sieving column were researched in subject. Diluted pulp with two or three kinds of particles maked spiral motion with fluid when they were pumped into spiral sieving column, the particles collided griddle surface by bevel or right-angle, when the particles gradually closed to the vessel wall by the collision force, centrifugal force and gravity, fine particles traversed the apertures under vertical function by rotating current and pore flow near griddle surface, Coarse particles bounced back and settled down, In the end it was successfully separated between fine and coarse particles. It was observed and researched about particles mechanical behavior at different stages in the process of sieving by using high speed camera and the laser velocimetry (PIV), especially the perspective of fine particles collided with the griddle surface, shape, speed, coarse particles were collisions with wire and aperture, rebounded and sedimentated. Moreover, sieving mechanism was researched with micro-flow boundary layer theory and the rotating flow separation theory. The topic provided the theoretical foundation for classification and theoretical basis and test data for designing spiral eddy classification equipment.

针对矿物加工领域的矿物颗粒群分级效率不高的问题，提出一种新型矿物颗粒群分级装置与方法。旋流分级抛开单独使用一种分级原理的方法，将筛分分级与离心分级优点结合于自主设计的旋流分级柱中进行思考。本课题以旋流分级柱分级装置为研究对象，两种或三种级配尺寸的颗粒群矿浆进入装置后随着高速流体做旋转涡流运动，在碰撞力、离心力、重力等为主的耦合作用力下，颗粒与筛面发生斜角或直角碰撞，颗粒靠近筛面边壁处时，在近壁面旋转流与筛孔的孔隙流垂直交叉作用下，细颗粒发生透筛行为，粗颗粒反弹回去，达到粗细颗粒筛分分离。采用高速相机和激光粒子测速仪（PIV）观测并研究颗粒筛分过程中不同阶段的受力行为，尤其是细颗粒与筛面碰撞的角度、形态、速度，粗颗粒与筛丝和筛孔的瞬态碰撞、反弹及沉降过程。应用微流边界层理论和旋转流分离理论分析筛分机制。课题为颗粒群高效分级提供理论研究基础，为高效旋转涡流分级设备研制提供理论依据与试验资料。

为提高矿物加工（选矿）领域中矿物颗粒群分级/筛分的精度和效率，根据研究目标，自主探索和研制一种新型分级设备（旋流分级柱）。配制不同粒级组成的颗粒群，进行分级/筛分试验研究，主要研究叶片旋转速度、颗粒级配组成、颗粒加料速度、矿浆浓度、分级时间等对分级/筛分效果的影响。试验表明：当柱形筛网直径90mm、筛网孔径0.25mm、长度420mm，柱筒直径300mm、长度450mm，叶片17层，中心轴转速为1000r/min，分级时间为10s时，分级质效率和量效率基本保持平稳，浓度为10%、12%、15%、18%和20%时的E质-0.25mm分别是88.32%、88.36%、89.32%、86.26%、85.67%，E量-0.074mm分别是92.03%、91.32%、90.62%、90.36%、90.12%，试验结果表明它比同尺寸的水力旋流器的颗粒分级效率（以-0.074mm颗粒为准）高出20~30个百分点。运用FLUENT数值模拟较好的解释了颗粒分级效率高的原因。课题为提供一种新型分级设备的高效分级技术提供思路和探索，为“筛网+旋流”结合的分级设备研究提供理论基础与技术参数。