Optimization of depth clarification device for beneficiation circulating water based on solid-liquid two-phase flow simulation
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摘要: 部分选矿循环水中含一定量的高分散性悬浮颗粒，仅依靠简单浓缩沉降难以澄清，无法达到回用要求。针对这一难题，提出了一种选矿循环水固体悬浮物澄清装置。为优化装置的结构参数与运行参数，建立了选矿循环水深度澄清装置的二维物理模型，基于计算流体力学（CFD）的方法，选用Mixture和RNG k‒ε 模型对装置主要的结构参数与运行参数展开了数值模拟研究。研究发现适当降低水力循环区喷嘴长度，增加喉管与喷嘴管径比、颗粒沉降区开口尺寸、装置直径等结构，能够降低颗粒沉降区平均湍动能，由于湍动能为单位质量流体由于紊流脉动所具有的动能，故降低了颗粒沉降区流场的紊流程度，增加了水流的稳定性，提高了装置对悬浮颗粒的去除效果；同时发现降低入口流速、增加悬浮颗粒粒径有助于提高悬浮物的去除率，当进水流速为0.1 m·s‒1、经过混凝的悬浮颗粒形成粒径大于100 μm时，装置对选矿循环水中的悬浮颗粒去除效果显著。Abstract: Some beneficiation circulating water contains excess highly dispersed suspended particles, which are difficult to clarify only by simple concentration and sedimentation and cannot meet the requirements of reuse. To solve this problem, a clarification device was developed for removing the solid suspended matter from beneficiation circulating water, which consists of a hydraulic circulation area and a particle sedimentation area and integrating mixing, flocculation, and sedimentation. The flow field inside the gadget has a big influence on how well it works. The structural and operating parameters of the gadget were improved using the computational fluid dynamics approach to increase the device’s performance. A two-dimensional physical model of the deep clarification device for beneficiation circulating water was established. Numerical simulation research on its main structural parameters and operating parameters were conducted by using software Fluent and choosing the Mixture multiphase flow model and RNG k‒ε turbulence model. The effects of feed water nozzle length, throat to nozzle diameter ratio, sludge settling area opening size, and device diameter on the internal flow field were investigated. The average turbulent kinetic energy in the sludge settling zone can be reduced by reducing the length of the nozzle in the hydraulic circulation region, increasing the ratio of the throat to nozzle diameter and the opening size of the sludge settling area, and increasing the diameter of the device. Due to the fact that the turbulent kinetic energy is the kinetic energy of fluid produced by turbulent pulsation, the turbulent degree of the flow field in the sludge settling area is reduced, the effect of turbulent flow in the flow field on particle settling is weakened, and the removal effect of the device on suspended particles is improved. Simultaneously, it is found that at the same suspended solids concentration, reducing the inlet flow rate or increasing the suspended particle size helps to improve the removal rate of suspended solids. When the inlet flow rate is 0.1 m·s-1 and the coagulated suspended particles form particles with particle size more than 100 μm, the removal effect of slime particles in beneficiation circulating water is remarkable.
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图 1 固体悬浮物处理装置结构简图
Figure 1. Structure diagram of deep clarification physicochemical reaction device
图 4 不同喷嘴长度对装置内部速度流场的影响. (a) 50 m; (b) 80 mm; (c) 110mm
Figure 4. Effect of nozzle length on velocity flow field inside the device: (a) 50 m; (b) 80 mm; (c) 110 mm
图 6 喷嘴长度对固体悬浮颗粒去除率η的影响
Figure 6. Effect of nozzle length on the removal rate of solid suspended particles η
图 5 喷嘴长度对颗粒沉降区平均湍动能的影响
Figure 5. Effect of nozzle length on average turbulent kinetic energy in sludge settling zone
图 7 管径比对装置内部速度流场的影响. (a) 管径比1.5; (b) 管径比2; (c) 管径比3
Figure 7. Effect of pipe diameter ratio on velocity flow field inside the device: (a) pipe diameter ratio of 1.5; (b) pipe diameter ratio of 2; (c) pipe diameter ratio of 3
图 8 管径比对颗粒沉降区平均湍动能的影响
Figure 8. Effect of pipe diameter ratio on average turbulent kinetic energy in sludge settling zone
图 9 管径比对固体悬浮颗粒去除率的影响
Figure 9. Effect of pipe diameter ratio on the removal rate of solid suspended particles
图 10 开口尺寸对装置内部速度流场的影响. (a) 开口尺寸50 mm; (b) 开口尺寸70 mm; (c) 开口尺寸90 mm
Figure 10. Effect of opening size on velocity flow field inside the device: (a) opening size of 50 mm; (b) opening size of 70 mm; (c) opening size of 90 mm
图 12 开口尺寸对固体悬浮颗粒去除率的影响
Figure 12. Effect of opening size on removal rate of suspended solids particles
图 11 开口尺寸对污泥沉降区平均湍动能的影响
Figure 11. Effect of opening size on average turbulent kinetic energy in sludge settling zone
图 13 装置直径对装置内部速度流场的影响. (a) 直径500 mm; (b) 直径600 mm; (c) 直径700 mm
Figure 13. Effect of device diameter on velocity distribution of flow field inside the device: (a) diameter of 500 mm; (b) diameter of 600 mm; (c) diameter of 700 mm
图 14 装置直径对污泥沉降区平均湍动能的影响
Figure 14. Effect of device diameter on average turbulent kinetic energy in sludge settling zone
图 15 装置直径对固体悬浮颗粒去除率的影响
Figure 15. Effect of device diameter on the removal rate of solid suspended particles
表 1 装置主要结构尺寸
Table 1. Main structure size of the device
mm H D h1 h2 h3 h4 h5 h6 d1 1220 500 155 450 440 60 190 95 25 d2 d3 L L1 L2 L3 L4 α β 50 380 70 80 15 60 50 140º 150º 
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表 2 装置运行参数对固体悬浮颗粒去除率的影响
Table 2. Effect of operation parameters on the removal rate of suspended solids
Inlet velocity/(m·s−1) Suspended particle size/µm η/% 0.1 60 25.11 75 30.26 100 60.98 120 80.36 0.12 60 18.3 75 24.13 100 45.96 120 70.46 0.15 60 17.16 75 18.41 100 26.11 120 46.18 0.18 60 11.54 75 15.6 100 23.6 120 29.1
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