离心场盘式分选过程数值模拟研究

发布时间：2018-06-10 20:46

本文选题：细粒矿物 + 离心分选　；参考：《中国矿业大学》2017年硕士论文

【摘要】：随着矿产资源被大规模的开发利用,大量低品位资源的开发与利用将成为重点,细磨是实现低品位矿物单体解离的主要方法,随之而来的微细粒成为矿物分选的难题。源于重力选矿技术的离心选矿技术,利用离心加速度替代重力加速度,能有效地提高固体颗粒的沉降速度,是解决微细粒分选难题的途径之一。盘式分选机作为离心分选机的一种,在其分离腔内有很多盘片,分离在盘片之间薄层内进行,通过缩短颗粒离心沉降的距离,从而可以提高分离效率。本文主要利用计算流体力学方法对该设备的分选性能与结构进行优化。首先,在旋转坐标系下,利用单相流场信息并结合DPM颗粒轨迹验证计算网格与计算模型,对盘片之间的流态运用斜面流流膜理论进行了判断。然后结合欧拉多相流模型,颗粒粒径对多相流场结构的影响,并对三种曳力模型Wen-Yu、Gidaspow、Huilin-Gidaspow 进行了比较,结果表明 Huilin-Gidaspow 的预测值较为接近试验值。因此,将Huilin-Gidaspow模型选定为本研究中的曳力模型。研究了三个关键操作参数:转速、入口速度、给料浓度,主要关注了操作参数因素对盘片之间分选区域轴向速度、切向速度以及固相体积分数的影响。以产率和功率为指标,设计了 L25 (5 6)正交试验表以评价操作参数的综合影响。结果表明影响产率的主次顺序为A (转速)、C (固相浓度)、B (入口速度),而对设备旋转功率影响的主次顺序为A (转速)、B (入口速度)、A (固相浓度)。其次,对五种盘间距(1.5 mm,2.5 mm,3.5 mm,5 mm,5.5 mm)与五种喷嘴直径(2.2 mm,2.6 mm,3 mm,3.3 mm,3.9 mm)进行了数值模拟研究,研究中操作参数参照了正交试验结果,选用欧拉模型耦合群平衡模型,计算了入料中粒径为15 μm与30 μm两种颗粒组分的分离效率。结果表明,小间距与大喷嘴有利于分离效率的提高。最后,使用数值模拟所研究的结构,加工后进行分选试验。比较四种盘间距与四种喷嘴结构分别对应的牛顿分离效率,试验结果表明盘间距由5.5 mm减小至1.5 mm,分选效率可以提高1.2倍;喷嘴直径由2.2 mm增加至3.9 mm,分选效率可以增加23.5%,即小间距与大喷嘴有利于分离效率的提高,与数值模拟的结论一致。本文的研究为细粒矿物的分选研究以及盘式分选机结构优化提供了一定的借鉴作用。
[Abstract]:With the large-scale development and utilization of mineral resources, the development and utilization of a large number of low-grade resources will become the focus. Fine grinding is the main method to realize the dissociation of low-grade mineral monomers, followed by micro-fine particles become the difficult problem of mineral separation. Centrifugal mineral processing technology derived from gravity dressing technology, using centrifugal acceleration instead of gravity acceleration, can effectively improve the settling speed of solid particles, which is one of the ways to solve the problem of fine particle separation. As one of the centrifugal separators, there are many disks in the separation chamber, which are separated in the thin layer between the plates. The separation efficiency can be improved by shortening the distance between the centrifugal settling of the particles. In this paper, the separation performance and structure of the equipment are optimized by computational fluid dynamics (CFD) method. Firstly, the single-phase flow field information and DPM particle trajectory are used to verify the computational grid and the computational model in the rotating coordinate system, and the sloping flow film theory is used to judge the flow pattern between disks. Then, the influence of particle size on the structure of multiphase flow field is studied by using Euler multiphase flow model. Three drag models, Wen-Yuan Gidaspowg Huilin-Gidaspow, are compared. The results show that the predicted value of Huilin-Gidaspow is close to the experimental value. Therefore, Huilin-Gidaspow model is chosen as the drag model in this study. In this paper, three key operating parameters: rotational speed, inlet velocity, feed concentration, and the effects of operating parameters on the axial velocity, tangential velocity and volume fraction of solid phase in the separation region between disks are studied. Based on the yield and power, the L 25 / 56) orthogonal test table was designed to evaluate the comprehensive effect of operating parameters. The results show that the primary and secondary order of the effect on the yield is A (rotational speed / C) (solid phase concentration) B (inlet velocity), while the primary and secondary order of the influence on the rotating power of the equipment is A (the inlet velocity is higher than A (solid phase concentration). Secondly, the numerical simulation of five kinds of disc spacing of 1.5 mm / 2.5 mm / 5 mm) and five kinds of nozzle diameters (2. 2 mm / 2. 6 mm / 3 mm / 3.9 mm) were carried out. The operating parameters of the study were based on the results of the orthogonal test and the Euler model coupling group equilibrium model was selected. The separation efficiency of two particle fractions with particle size of 15 渭 m and 30 渭 m was calculated. The results show that small spacing and large nozzle are beneficial to the improvement of separation efficiency. Finally, the structure studied by numerical simulation is used to carry out sorting test after processing. Compared the Newtonian separation efficiency between the four kinds of disc spacing and four nozzle structures, the experimental results show that the separation efficiency can be increased 1.2 times by decreasing the disc spacing from 5.5 mm to 1.5 mm. When the diameter of the nozzle is increased from 2.2 mm to 3.9 mm, the separation efficiency can be increased by 23.5. that is, the small distance between the nozzle and the large nozzle is beneficial to the improvement of the separation efficiency, which is consistent with the conclusion of numerical simulation. The research in this paper provides a reference for the study of fine mineral separation and the structure optimization of disk separator.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD922

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