基于数值计算的浮选机内颗粒流动行为研究

浮选机内矿浆动态流动性能研究对于优化浮选机具有重要意义。利用CFD数值模拟方法研究了浮选机内矿浆动态流动特性,并讨论了不同粒径矿石颗粒的分布特点,矿浆的动态流动并未破坏浮选机的循环流场结构,固相颗粒也形成了循环特征流场。单一固相粒径分析表明,随着给矿粒径的增加,浮选机槽底的沉积现象加重。多固相粒径分析表明,浮选机对不同粒级颗粒的提升能力和搅拌混合能力是不同的,为提高粗颗粒的回收能力,需要提高颗粒的提升高度。     

KYF型浮选机气泡特征参数分析与探讨—KYF浮选机流场测试与仿真研究(五)

浮选机内气泡特征参数和流动规律的研究一直是浮选机研究的重点和难点。本文利用电导探针法和CFD数值方法研究了浮选机内气泡特征参数及其分布特性。通过电导探针法获取了浮选机内气泡直径、速度和气含率等气泡特征参数。利用CFD数值方法揭示了浮选机内气含率的分布特征,预测结果同试验观察一致。并进一步研究了浮选机关键运转参数对气含率分布的影响规律。试验结果表明,CFD预测的气含率同试验测试结果吻合。     

KYF型浮选机内气泡特征参数分析与探讨——KYF浮选机流场测试与仿真研究(五)

浮选机内气泡特征参数和流动规律的研究一直是浮选机研究的重点和难点.本文利用电导探针法和CFD数值方法研究了浮选机内气泡特征参数及其分布特性.通过电导探针法获取了浮选机内气泡直径、速度和气含率等气泡特征参数.利用CFD数值方法揭示了浮选机内气含率的分布特征,预测结果同试验观察一致.并进一步研究了浮选机关键运转参数对气含率分布的影响规律.试验结果表明,CFD预测的气含率同试验测试结果吻合.     

基于试验和数值分析的浮选机停留时间分布特性研究

浮选机停留时间分布研究对于认识大型浮选机内短路和死区等异常流动具有重要意义。本文采用示踪试验的方法研究了实验室和工业浮选机的停留时间分布特性。电导率示踪法可以有效应用于实验室浮选机的RTD研究,而荧光示踪法可以解决工业浮选机三相体系下的RTD研究。应用CFD方法研究了动态体系下浮选机的流态特征,揭示了示踪剂在浮选机内的流动过程,CFD方法揭示出浮选机内的停留时间分布特征与理想搅拌反应器相似,说明具有很好的搅拌混合效果。在世界最大的680m3浮选机开展了停留时间分布特征研究,平均停留时间达到理想平均停留时间的89%,说明浮选机内短路和死区等异常流动较少。     

颗粒粒径对浮选机固—液两相流场分布特征影响研究

针对充气机械搅拌式浮选机,运用CFD流体模拟软件进行了颗粒粒径对浮选机固—液两相流场分布特征的影响研究。通过模拟分析可知:离散相矿物颗粒与连续液相两相之间相互作用较小,流场分布特征基本保持一致,微细粒矿物颗粒粒径对浮选机内部固—液两相流场特性影响较小。转子及定子表面压力分布值与颗粒粒径有较大的关系,且在此处区域附近湍流动能较大,保证了矿物颗粒在该区域的较好分散性。     

PDA测试浮选柱液—固—气三相流中颗粒的流速分布

采用ＰＤＡ流速测试技术,对ＬＨＪ浮选柱下导管内液－固－气三相流中固体颗粒的流速进行了测定,获得了浮选柱内液－固－气三相流中固体颗粒沿径向和轴向的湍流速度分布,证实了ＬＨＪ浮选柱内形成泡沫流时,下导管内固体颗粒运动处于强烈的脉动状态,从而为揭示其矿化作用机理,建立数学模型及放大提供了理论依据。     

基于CFD-DPM模型的浮选机内固相颗粒行动行为研究

矿物颗粒在浮选机内部的运动状态是优化研究浮选机性能的基础。采用计算流体力学仿真技术,使用欧拉-拉格朗日方法（CFD-DPM）模拟研究了浮选机内部固相颗粒的运动行为:采用单一粒径的石英固体颗粒,在单向耦合条件下研究颗粒运动轨迹随时间的变化,揭示流场对固体颗粒的影响;在完全耦合条件下研究颗粒运动轨迹随时间的变化,揭示颗粒与流场的相互作用。      

粗颗粒矿物在矿浆相中的悬浮特征

浮选过程中颗粒的悬浮是气泡与颗粒碰撞和黏附的基础条件。粗颗粒矿物由于尺寸较大,在矿浆相中的悬浮特征有别于常规粒级和细粒级矿物。为了分析粗颗粒在浮选机矿浆相中的悬浮影响因素,以层析度函数为分析手段,选取金矿、钛铁矿、黄铜矿三种浮选系统中的四种规格浮选机中的粗颗粒为研究对象,研究了三种矿物在单槽浮选机内、沿作业分布、随浮选机规格变化等情况下的悬浮特征。结果表明:在单体浮选机竖直截面内,粗颗粒矿物在叶轮上方悬浮效果比其它粒级差,随着高度的增加重量层析度迅速减小;沿作业分布的三台同规格浮选机内的粗颗粒矿物悬浮特征相近;而浮选机的规格大小对粗颗粒的悬浮特征影响不敏感,给矿粒级分布和矿物的比重对粗颗粒的悬浮特征影响强烈。在同一浮选机槽体,固相颗粒重量分布层析度与金属量分布层析度两者变化并不一致,粗颗粒分选环境尤其明显,这为粗颗粒浮选机的设计提供了新的思路。     

充气搅拌式浮选机流场特性模拟研究

采用计算流体力学方法模拟了充气机械搅拌式浮选机的流场分布,分别讨论了单一液相、液气两相以及固液气三相条件下浮选机的流场特性,并讨论了液相条件下浮选机流场对转子和定子磨损的影响。研究结果对于进一步改进改善浮选机的分选效果以及开发高效浮选设备具有指导意义和实际应用价值。     

气固两相穿越液池过程颗粒运动分离特性研究

采用可视化实验和数值模拟方法对气固两相流穿越液池过程中气液固三相流动进行研究。揭示了入口流速、颗粒直径和下降管的浸没深度对颗粒运动分离的影响及颗粒运动分离过程,获得颗粒在液池中的分离机理。研究获得,气固两相穿越液池过程中,大直径的颗粒向液池底部沉降,小直径的颗粒在液池中悬浮;入口气速增大对小粒径颗粒影响明显,对大粒径颗粒影响较小;下降管浸没深度的增大对颗粒浓度分布影响较小。     

鼓泡流化床排渣流动的模拟与实验研究

基于计算颗粒流体力学(CPFD)方法,研究了鼓泡流化床的排渣流动特点,获得了不同管径的排渣管对流化床排渣流率的影响,并对排渣流动的流场进行了详细分析。模拟结果表明,布风板上开孔排渣会影响床内的正常流态化,随排渣管径的增大所影响的区域也会逐渐增大;排渣流率与流化风速、床层压降和管径的平方呈现出正相关性。根据流体力学拟流体理论所建立的公式能较好地预测排渣流率的变化趋势,从排渣流动过程中颗粒体积分数的梯度分布可知,布风板上排渣口的上方存在一个拱形临界面,此临界面是排渣过程中颗粒流动形态发生转变的分界面。     

自吸气浮选机模拟研究

为加深对自吸气浮选机槽体内的流场结构及性能参数的认识,运用CFD仿真技术对自吸气浮选机槽内气-液两相流进行了模拟研究。以实验室JJF-0. 2 m~3自吸气浮选机为原型进行仿真建模,采用六面体网格对整个模型进行网格划分的网格数量为1. 6×10~6。采用Euler-Euler双流体模型对气-液两相流进行稳态模拟仿真,运输方程的计算运用商业软件ANSYS-FLUENT软件。自吸气浮选机的吸气速率不能预先设定,需要通过模拟结果给出。我们设定气相为单一粒径的气泡,直径为1 mm。模拟过程中监测了叶轮区的气含率及功耗,结果表明浮选机处于良好的操作状态。分析了槽内不同区域的气含率云图及速矢量图,对自吸气浮选机内的流场有一个直观的认识。     

东鞍山含菱铁矿赤铁矿石分级浮选试验研究

东鞍山烧结厂矿石铁品位为32.45%,具有贫铁、高硅的特点,主要铁矿物为赤铁矿,主要脉石矿物为石英,同时含有少量的菱铁矿和磁铁矿,是一种含菱铁矿赤铁矿石。对磨矿细度为-0.074 mm占70%的产品筛分分析表明,随着粒度的增加,各粒级铁品位逐渐增大,铁矿物单体解离度逐渐减小。在该磨矿细度下进行分级浮选闭路试验,-0.074 mm粒级以柠檬酸为分散剂、氧化钙为活化剂、淀粉为抑制剂、KS-Ⅲ为捕收剂,+0.074 mm粒级以淀粉为抑制剂、十二胺为捕收剂,可获得精矿铁品位63.30%和铁回收率71.32%的浮选指标。与全粒级浮选相比,分级浮选可减弱微细粒矿物的黏附罩盖,提高浮选指标。     

Flotation bank air addition and distribution for optimal performance

Recent studies have shown that varying the distribution of a set volume of air to a flotation bank significantly affects the performance of the bank. To date, however, the volume of air to be distributed has usually been arbitrarily set as that added with the ‘as found’ air rates, the typical operating air rates; not necessarily an optimum.Studies examining the effect of different total air additions, at a constant distribution, have shown the addition maximising air recovery typically yields the best performance. Air recovery is the fraction of the air added to a cell which overflows the lip of the cell as unburst bubbles and shows a peak with respect to cell aeration.In this work three experimental case studies are presented to examine of the role of aeration in flotation performance, with the aim of developing a generic technique to determine both the required total air addition and distribution of air to a bank of flotation cells.The first case study compares performance at three different total air additions. The air addition which gave the Peak Air Recovery (PAR) also gave the highest mineral recovery. Thus air recovery optimisation yields the optimum total air addition to a flotation bank. In the second case study the air recovery was optimised from each cell in a bank individually. The PAR air addition once more gave the highest mineral recovery from the bank. Therefore, air recovery optimisation determines the optimum total air addition to a bank and also provides a distribution for that air. The third case study compares a profile based on the PAR air rates with other distributions of the same total air. The results show the profile based on the PAR air rates gave a significantly higher cumulative mineral recovery than other distributions of the same volume of air, for the same cumulative grade.The results of the three case studies show air recovery optimisation of each cell in a bank is a robust and generic technique to simultaneously determine the optimum bank aeration and the optimum distribution of this air within the bank.     

Predicting plant scale flash flotation performance – Validation of laboratory methodology and applications for use

A method has been developed in which laboratory batch flotation test results can be used in conjunction with mineralogical analysis to determine whether an ore is amenable to successful recovery via the flash flotation processing route. In the original development work, using a high grade refractory gold ore, a direct correlation was found with the particle properties of the plant flash flotation cell concentrate and a concentrate produced by a targeted laboratory batch flotation test. The respective concentrates were observed to have nearly identical distributions of the target elements (Au, S and Fe) by size as well as almost identical liberation characteristics of the key mineral (pyrite) for flotation. A second ore from the same mine, but of significantly lower grade and different grinding characteristics has now been tested to determine if the same correlations exist that were observed with the previous work and to provide further insight into the differences between laboratory and plant response in order to potentially refine the procedure further and enhance its usability as a predictive tool.Testing of the second ore confirmed the original findings that a targeted laboratory batch flotation test can produce a concentrate with a target mineral (pyrite) distribution by size and liberation that matches the concentrate produced by the industrial scale flash flotation cell whilst treating the same feed material. Further to this, grades of the intermediate size classes in the laboratory concentrates were found to be similar to those of the plant flash cleaner cells.From the correlations in performance observed with both ore types in the laboratory batch cell and plant flash flotation cell, methodologies are proposed that can be used to determine:

• •whether a new ore could be treated by flash flotation in a plant with an existing flash flotation circuit;
• •whether a plant operating without an existing flash flotation circuit could benefit from installing one; and
• •the amenability of an ore to the flash flotation process for greenfield flow sheet development.

A step wise approach is given for each to allow the method to be applied to and adapted for other ores and valuable mineral types. The advantage of following this methodology exists in that no specialised equipment or analysis methods are required to perform the test. Standard laboratory equipment has been used throughout the test-work and mineralogical analysis performed via commercially available MLA. The procedure is kept as basic as possible to allow for maximum usability on sites where only essential laboratory equipment exists.     

循环流化床锅炉飞灰微观特性的研究

从微观角度入手,通过氮吸附仪、压汞仪和扫描电子显微镜观测了某循环流化床锅炉中不同粒径段飞灰颗粒的微观特性。结果表明：飞灰的含碳量与其粒径之间具有峰值特征;不同粒径段飞灰的吸附等温线均近似为第Ⅱ类;孔类型主要为锥形孔、平行板狭缝孔和墨水瓶状孔;孔径分布很宽,但未发现2 nm以下的孔;飞灰的孔径分布从几纳米至几万纳米,最可...