含金废液脱氰过程固—液搅拌的数值模拟

为提高含金废液在搅拌槽内脱氰过程的搅拌效果,针对脱氰过程的搅拌槽内流场及固—液分散进行数值模拟研究。模拟实验采用多重参考系法和欧拉双流体模型,考察转速、偏心率对脱氰过程的槽内速度场、流场流型、固含率分布以及搅拌功率的影响。结果表明:偏心搅拌能够明显改善对称的速度场和流型,当偏心率e=0.2时流场状态最佳;当e0.2时,近壁侧上、下循环涡向桨叶区靠近,远壁侧桨叶上方则出现较大尺度的弱湍动循环涡,不利于混合;e在0~0.2范围内有利于脱氰药剂的分散,过大的偏心程度反而会使脱氰剂堆积在近壁侧挡板处。当转速从100 r/min增大至1 200 r/min,功率增速越来越快,两相搅拌功率比单相搅拌功率高8.8%;偏心搅拌具有节能功效,当e从0增大至0.43时,搅拌功率降低3.9%。

Numerical Simulation of Solid -Liquid Mixing in Stirred Tank During Decyanation Process of Gold-Containing Wastewater

In order to improve the decyanation stirring effect of gold-containing wastewater in the stirred tank,a numerical simulation of the flow field and the solid-liquid dispersion was carried out.Multiple reference frame method and Euler- Euler model are used in the simulation experiment.The effects of rotational speed,eccentricity on the velocity field,flow pattern,solid holdup distribution and mixing power in the decyanation process were investigated.The results show that the eccentric mixing can significantly improve the symmetric velocity field and flow pattern,and the flow field is the best when the eccentricity is e=0.2.The near wall lateral flow is enhanced when eccentricity is greater than 0.2,the near-wall circular vortex close to blade area.There is a large circular vortex with weak turbulence in far-wall area,which is not conducive to mixing.Eccentricity is conducive to the dispersion of decyanation agent in the 0~0.2 range.But a large degree of eccentricity will cause the accumulation of cyanide in the near wall side baffle plate.Agitation speed increased from 100 r/min to 1 200 r/min,the power growth rate is more and more fast.The power of two phase mixing is 8.8% higher than that of single phase stirring. Eccentric agitation has the energy saving effect,when the eccentricity increases from 0 to 0.43,the stirring power is reduced by 3.9%.