微细粒赤铁矿絮聚体两相流体特征研究

发布时间：2018-07-03 00:54

本文选题：微细粒 + 赤铁矿　；参考：《华北理工大学》2017年硕士论文

【摘要】：絮凝浮选过程中,流体变化使能量的传递以及颗粒的行为发生改变。试验以微细粒赤铁矿为研究对象,考察了絮凝过程中搅拌槽内流体变化对絮聚体粒径以及分形维数的影响,并结合ANSYS数值模拟软件对搅拌槽内流体的变化进行数值模拟,在此基础上对搅拌槽内流体状态和颗粒行为进行初步研究。通过试验研究搅拌转速、搅拌时间、轴向距离和搅拌槽形状等条件的变化对絮聚体性质的影响,并采用响应曲面法进行结果优化可知,在方形搅拌槽中,当搅拌转速为880r/min,搅拌时间为3.2min,轴向距离为2cm时,絮聚体的粒径为35.59μm,分形维数为1.6689,性质较好。在试验基础上,对搅拌转速、轴向距离和搅拌槽形状等条件进行数值模拟,由结果可知,在搅拌转速为880r/min,轴向距离为2cm,搅拌槽形状为方形时,搅拌槽内速度、湍流动能的分布以及转子所受压力均在较适宜的范围。经搅拌槽内流体力学分析可知,流体一直处于完全湍流状态,随着搅拌转速的增加,平均能量耗散、有效能量耗散、速度梯度以及Gt值逐渐上升,湍流微尺逐渐下降。当搅拌转速为880r/min时效果较好,此时平均能量耗散为0.1972 m2/s3,有效能量耗散0.1696 m2/s3,湍流微尺为47.5731mm,速度梯度为511.14s-1,Gt值为98139.2。经过颗粒行为分析可知,在Re104,介质相同的条件下,絮聚体的密度与其跟随性成正相关。对于絮聚体形成时搅拌槽内颗粒碰撞概率的分析,Levich模型不仅考虑到了颗粒自身的性质,还考虑到了流体的性质,适用性更强。文中通过条件试验、数值模拟以及流体力学和颗粒行为分析,对微细粒赤铁矿絮聚体形成过程中水力学条件的影响进行研究,研究结果为生产实践提供了理论基础与数据支撑。
[Abstract]:In the flocculation flotation process, the fluid change makes the transfer of energy and the behavior of the particles change. In the experiment, the influence of the fluid change on the particle size and the fractal dimension of the floc during the flocculation process was investigated, and the numerical simulation software of ANSYS was used to carry out the numerical value of the fluid in the stirred tank. On the basis of the simulation, the fluid state and particle behavior in the stirred tank are preliminarily studied. The effects of the changes of the stirring speed, stirring time, the axial distance and the shape of the stirred tank on the properties of the floc are studied by experiments, and the response surface method is used to optimize the results. In the square stirred tank, the stirring speed is 880r/mi N, when the stirring time is 3.2min and the axial distance is 2cm, the particle size of the floc is 35.59 mu m and the fractal dimension is 1.6689. On the basis of the experiment, the stirring speed, the axial distance and the shape of the stirrer groove are numerically simulated. The results show that the stirring speed is 880r/min, the axial distance is 2cm, and the shape of the stirring tank is square. The velocity, the distribution of turbulent kinetic energy and the pressure of the rotor are in a suitable range. Through the fluid mechanics analysis in the stirred tank, it is known that the fluid has been in a complete turbulent state. With the increase of the stirring speed, the average energy dissipation, the effective energy dissipation, the velocity gradient and the Gt value gradually rise, and the turbulence microscale gradually decreases. When stirring, the stirring is gradually reduced. When the rotational speed is 880r/min, the average energy dissipation is 0.1972 m2/s3, the effective energy dissipation is 0.1696 m2/s3, the turbulence microscale is 47.5731mm, the velocity gradient is 511.14s-1, and the Gt value is 98139.2. through the particle behavior analysis. The density of the floc is positively related to the following property under the same conditions of Re104 and the medium. For the flocculation body shape, the floc shape has a positive correlation with the floc shape. The analysis of particle collision probability in a time stirred tank, the Levich model not only takes into account the properties of the particles, but also takes into account the properties of the fluid, and the applicability is stronger. In this paper, the effects of the hydrodynamic conditions on the formation of the floc during the formation of fine Hematite floc are carried out by conditions test, numerical simulation, fluid mechanics and particle behavior analysis. The research results provide theoretical basis and data support for production practice.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD951;TD923

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