平底沉降槽内固液分离与赤泥沉降的数值模拟

采用计算流体力学软件Fluent、简化的三维Eulerian两相流和Realizable k-e湍流模型，并结合SIMPLE算法对直径40 m的氧化铝赤泥沉降槽内的固液分离过程进行数值模拟，以得到槽内流场形态和赤泥浓度的分布规律. 通过对比计算结果和现场测试数据，并结合自定义分析评价指标，分析了有无溢流围堰和中心下料桶的不同进料方式下沉降槽的固液分离和赤泥沉降的流动规律. 结果表明，去掉沉降槽的溢流围堰后浆液的固相浓度降低84.3%；采用自吸式射流进料管，60~64 g/L固相浓度范围内的浆液在中心桶内所占体积由3.70%提高到14.36%，可有效促进中心桶内赤泥浓度分布的均匀性，提高平底沉降槽内赤泥的沉降分离效率.

Numerical Simulation on Separation of Solid with Liquid and Sedimentation of Red Mud in a Flat Bottom Thickener

The solid-liquid separation process in an alumina red mud flat bottom thickener with the diameter of 40 m was simulated using the commercial CFD software Fluent and combining the simplified 3-D Eulerian two-phase model, realizable k-e turbulence model and SIMPLE algorithm. The flow patterns and solid red mud distribution in the thickener were analyzed and the arrangements for the overflow weir and feed inlet for feedwell proposed. The simulation results were verified by field measurements. Further simulation was carried out based on the optimum proposal. Combined with the self-defined evaluation criteria, the obtained results indicated that the solid concentration of overflow was decreased by 84.3% when the overflow weir was removed. And the fluid volume fraction lying in 60~64 g/L in the feedwell was increased from 3.70% to 14.36% after adopting the self-sucking jet pipe in the feed pipe, which could elevate the homogeneity of solid distribution in the feedwell, and enhance the sedimentation efficiency in the red mud thickener.