浮选机内部气-液两相流场特性研究

Study on Flow Field Characteristics of Gas-liquid Two Phase in Flotation Machine

本物浮选过程中的多相流体特征直接影响矿物分选效率,针对有效容积为0.1m^3的充气机械搅拌式浮选机,运用计算流体力学对浮选机内部气-液两相流体特性进行数值模拟计算,分析了矿物浮选过程中复杂的流体特性。基于CFX流场数值模拟软件,建立了气-液两相流场数值模拟策略,通过对比标准k-ε湍流模型和RNG k-ε湍流模型,确定了离散气相-零方程、连续液相标准k-ε湍流模型的数学模型,探究了不同表面张力、曳力相间作用力对浮选机内部气—液两相流场特性的影响,模拟了充气强度和搅拌强度对浮选机内部气—液两相流场的影响。研究结果表明:表面张力系数在浮选机内部气-液两相流场数值模拟研究中影响很小,选定较为常用的表面张力系数0.073为模拟标准;Grace曳力模型适合充气机械搅拌式浮选机气-液两相流场的数值模拟;浮选机充气速度应小于2.0 m/s时,此时气相流场速度分布较均匀,气相逸散性较好;浮选机转子转速每增加50 rpm转子和定子表面受压大约增加300 Pa,中等转速450 rpm适合该类型浮选机的浮选作业,气-液两相流体特性模拟结果将为浮选工艺参数的设定提供基础理论指导。

The characteristics of multi-phase fluid in the process of flotation have direct influence on separation efficiency. Computational fluid dynamics were applied to conduct numerical simulation computation and analyze the complex fluid characteristics in the process of flotation aiming at the gas-fluid two phase fluid characteristics of the air-blowing mechanical flotation machine with effective volume of 0.1m3. Based on CFX numerical simulation software, gas-fluid two phase flow field numerical simulation strategy were. established. Through comparing standard k-g turbulence model and RNG k-e turbulence model, discrete gas phase-zero equation and the mathematical model of continuous liquid phase standard k-e turbulence model were confirmed, the influence of acting force of different surface tension and drag force on gas-fluid two phase flow field characteristics were investigated, the influence of inflation intensity and stirring intensity on gas-fluid two phase flow field were simulated. The research results： The influence of surface tension coefficient on the research of gas-fluid two phase flow field numerical simulation within flotation machine was minimal, so the common surface tension coefficient（0.073） was selected as simulation criterion; Grace drag force model was suitable for the gas-fluid two phase flow field numerical simulation of air-blowing mechanical flotation machine; When the aeration rate of flotation machine was less than 2.0m/ s, the velocity distribution of gas phase flow field was relatively even, the gas phase fugitive emission was better; The rotator speed of flotation machine every 50 increase, the surface pressure of rotor and stator increased approximately 300Pa,mid rotating speed（450 rotate/min） was suitable for this type of flotation machine to conduct flotation operation, the simulation results of gas-fluid two phase fluid characteristics will provide basic theoretical guidance for the setting of flotation technical parameters.