Air entrainment rate and holdup in the Jameson cell

Air entrainment rate and holdup are important and potential control parameters in plunging liquid jet bubble columns. In this study, air entrainment and holdup in laboratory Jameson cell downcomer were investigated in an air–water system. Air entrainment flow rates and holdup were quantified experimentally. The effects of various conditions in the nozzle diameter, the downcomer diameter, the free jet length, the jet velocity and the ratio of air-feed flow rate on gas holdup and air entrainment were studied. Two empirical equations were proposed to estimate gas holdup. The predictions from these equations are in good agreement with the experimental data for holdup.     

Effect of Jameson cell operating variables and design characteristics on quartz-dodecylamine flotation system

The Jameson cell is a relative newcomer to separation science and technology. Its mode of operation and mechanisms differ drastically from the other flotation machines. It has a number of unique parameters affecting flotation performance. An experimental investigation of Jameson cell operating variables and some design features was carried out within the quartz-dodecylamine flotation system. These parameters included jet length, bias, % solids, downcomer plunge length, and tank diameter studied for up to three different particle size groups (i.e., −250 + 106, −106 + 53 and −53 μm). The recovery of the medium and coarse size particles dropped by 10–15% as the free jet length increased, while that of fines was nearly independent of it. The bias factor negatively affected the recovery of all three size groups almost by same proportion. The effect of the downcomer plunging length on recovery was generally negative, but it was significant only for the coarsest size groups when the plunging length was beyond 50 cm. These negative effects on flotation recovery were mostly attributed to turbulence and its particle size dependent characteristics.     

The effect of particle porosity on liquid holdup in heap leaching

The inter- and intra-particle porosities of heaps have two distinct length scales (of order millimetres between the particles versus tens of microns within the particles) and therefore the dominant flow mechanisms within and around the particles are quite different. This paper investigates the effect of particle porosity on heap hydrodynamics by comparing the behaviour of a model system consisting of non-porous glass beads with a system of actual ore particles. The overall liquid holdup behaviour of these two systems initially appears quite different. However, when the effect of the liquid holdup around the particles is separated from that within the particles, the same theoretical flow model can be applied to both the model and ore systems. This demonstrates that correlating the liquid flow to the overall liquid holdup is problematic and that the effect of the inter- and intra-particle liquid holdup should be considered separately. This is important as the amount of liquid held within the ore particles in these experiments was nearly as large as that held around the particles. The model for the external liquid flow proposes a power law relationship between the relative flow rate (flow rate divided by residual holdup) and the excess relative holdup (the steady state liquid holdup divided by the residual holdup minus one) with an exponent of two. It was found that the pre-factor in this relationship was quite a strong function of particle size for the spherical glass beads, but relatively constant for the more angular ore particles.     

基于CPFD多密度电子垃圾颗粒分离影响研究

基于电子垃圾绿色、高效的分离回收需求,利用barracuda仿真软件建立电子垃圾颗粒气固分离模型,模拟电子垃圾颗粒在气流作用下的分选特性,探讨在不同气流参数及不同物料流量、不同粒径下电子垃圾各组分颗粒的分离效率和回收率。研究表明,电子垃圾颗粒下落流量与粒径对贵金属回收分离有显著影响,当一次进风的气流速度为3.8m/s、二次进风的气流速度为4.6m/s、入料开口宽度为4mm,颗粒粒径为75~100um时,Au的品位率和回收可达87.1%和99.1%,Cu的品位为70.8%,回收率为85.8%。说明在二次进风的作用下,改变电子垃圾流量和控制粒径大小可以有效提升电子垃圾中贵金属的品位和回收率,同时对多密度颗粒的分选提供参考和借鉴。     

煤层气井射流冲煤粉装置冲击深度的研究

为确定煤层气井射流冲煤粉装置合理的结构和工作参数,实现射流冲煤粉系统的优化设计和有效运行,理论分析了冲煤粉装置工作原理和煤粉颗粒运动过程,整个井底冲煤粉射流场可分为:自由射流区、射流冲击区、漫流区、返流区、旋涡区和负压吸附区6个区域,决定煤粉是旋转上升的复杂运动状态。开展均匀设计方法的冲煤粉实验,运用二次多项式逐步回归法得出回归方程,揭示喷嘴结构参数、射流参数和煤粉特性对冲煤粉深度的互相耦合的影响关系。结果表明,对冲煤粉的深度影响程度的大小依次为:喷距、喷嘴直径、喷嘴流量和煤粉直径。进一步的单因素试验详细了解各影响因素对冲煤粉深度的影响,得出在要求不动管柱时冲煤粉深度达到500 mm的条件下,喷嘴流量不能低于15 m3/h,喷距应小于100 mm。     

磨料射流喷嘴外流场磨料速度模型及分析

喷嘴外流场磨料速度是建立磨料射流冲蚀深度模型的重要前提,以磨料射流喷嘴外流场磨料为研究对象,以固液两相流理论为基础,建立了磨料射流喷嘴外流场磨料速度模型,基于位移等分法和迭代算法求解了该速度模型,利用PIV实验进行验证,实测值与理论值的平均百分比误差在5%之内。并利用该速度模型得到了磨料射流喷嘴外流场磨料运动规律:(1)磨料颗粒流在喷嘴外流场的流动具有扩散性;(2)磨料颗粒沿射流轴向运动时,大多经历了一个先加速后减速的过程,只是加速距离有所差异;(3)初始段内相同轴向距离的射流横截面上,位于等速核区域内的磨料速度相同,随后磨料速度从等速核边界朝射流边界方向逐渐减小;初始段末端及基本段内相同轴向距离的射流横截面上,磨料速度沿射流径向的分布完全呈现出钟形速度分布。     

带射流方腔内气固流动实验与模拟

使用PIV实验和数值计算研究了壁面射流下主流中的100μm颗粒运动分布。在气固两相主流中引入一股不含尘气流,能够影响颗粒在流道内的分布,形成沿流动方向和高度方向的不均匀分布。结果显示:射流速度越高,流场中心低浓度颗粒区域越大,射流孔后位置越远,流场中心低浓度颗粒区域越大,但壁面附近浓度增加。改善小颗粒的主动流动控制手段,为设计出高效的惯性粒子分离器提供依据。     

自制逆流分选柱用于低品位黄锑矿预富集的流场模拟及试验研究

采用自制逆流分选柱对某低品位黄锑矿进行摇床分选前的预富集以提高分选效率,并采用FLUENT 16.0数值流场模拟软件仿真与实际试验相结合的方法,研究了不同操作参数下的分选状态与效果.粒度范围-0.074+0.023 mm、Sb品位0.82％的实际矿物分选试验结果表明,在给矿质量浓度30％、底流流量50 mL/min、上...     

An experimental study of the recovery of hydrophilic silica fines in column flotation

This paper presents results of tests performed to investigate the effect of gas rate (1.2–2.5 cm/s), hydrophilic fines content (5–20% w/w silica) and froth depth (10–30 cm) on fines recovery in a laboratory-scale flotation column operating without wash-water addition and absence of floatable particles. A model was developed based on the entrainment coefficients presented by [Trahar, W.J., 1981. A rational interpretation of the role of particle size in flotation. International Journal of Mineral Processing 8, 289–327], which describes the mass contribution of the different size classes to the solids recovered in the concentrate. The entrainment model of [Zheng, X., Johnson, N.W., Franzidis, J.P., 2006. Modelling of entrainment in industrial flotation cells: water recovery and degree of entrainment. Minerals Engineering 19, 1191–1203] was also tested. The results show both models described well the dependence of the mass flow rate of hydrophilic solids in the concentrate.     

镜铁山V矿体铁矿石智能与强磁干式联合预选试验研究

酒钢镜铁山V矿体铁矿石采出TFe品位23%左右,多年来受选矿工艺技术水平及经济条件制约,一直未得到合理利用。现场采用单一强磁预选工艺,入选矿石TFe品位得到较为明显的提高,但尾矿TFe品位偏高,铁损失较大。为进一步提高预选效果,对该矿进行智能预选与强磁预选联合抛废试验研究。结果表明：①对于TFe品位为23.92%、粒度范围为15~45 mm粒级样,适宜的抛废率为16.31%,此时TFe品位为26.53%、回收率92.83%。抛废率为13.20%和20.39%的稳定试验结果与条件试验结果基本一致,表明智能预选试验数据可靠。②A1粒级样（30~45 mm）粗选适宜的筒体表面线速度为0.70 m/s,此时精矿TFe品位为29.03%、回收率70.91%;A2粒级样（15~30 mm）粗选适宜的筒体表面线速度为0.85 m/s,此时精矿TFe品位为30.03%、回收率78.09%。③粒度为30~45 mm的智能预选精矿通过强磁干式预选,可抛除作业产率为15.04%、TFe作业回收率为8.29%的尾矿,精矿TFe品位提升了2.04个百分点;粒度为15~30 mm的智能预选精矿通过强磁干式预选,可抛除作业产率为10.97%、TFe作业回收率为5.79%的尾矿,精矿TFe品位提升了1.54个百分点。粒度为30~45 mm的智能预选精矿的强磁干式预选效果更好。④采用智能预选—强磁干式预选（1粗1扫）工艺进行联合抛废处理15~45 mm粒级矿样,可抛除总产率为24.12%、TFe回收率为11.95%的尾矿,精矿TFe品位提升了3.85个百分点,预选效果较好。     

螺旋分选机动力学分析及参数优化探讨

为了探索螺旋分选机主要结构参数对颗粒运动规律的影响,基于螺旋线的形成特性,利用微元的思想将颗粒在螺旋槽上复杂的受力进行简化,推导出集物料性质、螺旋分选机结构参数为一体的数学模型;以1.0~0.5 mm粒度级的不同密度级粗煤泥为入料,探究了不同密度级颗粒在螺旋分选机出料端沿径向的分布情况,与数学模型分析出的结果进行对比验证,并分析了螺距、流量、螺旋槽内径和槽深等参数对颗粒达运动平衡后径向距离的影响;结果表明:提出的数学模型可以定性分析颗粒在螺旋分选机中的运动行为,颗粒密度越大,其平衡半径越靠近螺旋槽内缘;颗粒达平衡状态后的径向距离随螺距、流量以及内径的减小而减小,随槽深的减小而增加;较小的螺距、较小的内径和较大的槽深有利于粗煤泥的分选。     

JJF-130m^3机械搅拌式浮选机动力学研究

对三种转速叶轮、四种浸没深度进行了分析,叶轮线速度为6.6m/s即主轴转速105r/min、浸没深度510mm时,JJF-130m~3机械搅拌式浮选机动力学测试效果最佳。在最佳转速和最佳浸没深度条件下进行了浮选动力学研究,主要测量了吸气量、空气分散度、转速、功率、空气保有量等有关参数,并分析了吸气量与空气分散度、功率、空气保有量的关系,通过分析可以看出JJF-130m~3浮选机性能优良。     

进气速度与质量流率对多密度颗粒分离性能的影响研究

通过建立多密度颗粒在康达效应下的分离模型,利用不同密度颗粒在康达壁附近迁移轨迹不同而实现不同颗粒间的分离。基于计算颗粒流体力学(CPFD)方法模拟混合颗粒在该模型下的流动迁移特征,反映出不同密度颗粒在不同进气速度与质量流率的分离特性。研究表明,进气速度与质量流率对不同密度颗粒在康达壁下的迁移轨迹及分布均具有重要影响,当气流速度为2.8 m/s,质量流率为10 g/s时,在420～480 mm区间,矿粒铜的回收率可达65%,品位可达78%,富集比可达9.75,在480～520 mm区间,矿粒钨回收率可达59.50%,品位可达72%,富集比可达18,说明在康达效应下可以有效的分选富集高密度金属矿粒铜和钨,对多密度颗粒的分选具有借鉴作用,同时可为我国西北水资源贫乏地区金属矿的分选提供新的思路。     

高硫高砷金精矿三相流化床流动特征模拟

常温常压条件下基于欧拉模型, 利用Fluent软件对高1.6 m、内径0.09 m的高硫高砷金精矿三相流化床流动特征进行了数值模拟。模拟过程以空气为气相且为连续相, 液态水为液相, 密度为3.2 g/cm3、粒径为0.5 mm的高硫高砷金精颗粒为固相。模拟结果显示, 流场的压力从计算域的入口到出口逐渐降低,速度场的变化对气液固局部相含率的分布影响显著; 在径向上, 气含率(ε_g)从计算域中心往边壁降低, 在轴向上也逐渐降低; 固含率(ε_s)从计算域的入口到出口逐渐减小, 从计算域中心向边壁ε_s增加。模拟结果与实验结果一致, 可为合理设置气流速度以及金矿投放量提供依据。     

电选摩擦器气体流动及单颗粒运动特性研究

为研究电选摩擦器内气固运动特性,建立了三种摩擦棒不同分布特征的摩擦器数学模型,运用标准k-ε湍流模型及颗粒轨道模型,对摩擦器内气固两相流流场进行了数值模拟,主要研究了气体相对压力场、相对速度场分布情况;并以粒径为10、40、74μm的球形颗粒为研究对象,分析了编号43的单个颗粒运动情况。研究结果表明,摩擦棒对气体流动过程的干扰作用明显,摩擦棒间距对气相流场分布影响很大;摩擦棒背部的负压区和回流区面积沿气体运动方向逐渐增大;摩擦棒分布特征和粒径对摩擦器内颗粒速度变化趋势影响大,颗粒粒径与运动轨迹长度成正比,与速度成反比。     

基于EDEM—FLUENT耦合矿物颗粒分离效果的模拟研究

为了能同时依据矿粒的密度和粒度对其分离,尝试选用水平冲击水流和振动作用的联合分离工艺,采用EDEM-FLUENT耦合方法,以矿粒的回收率及分离产品含杂率为评价指标,对矿粒在分选装置中的分离行为进行模拟研究,并探讨不同工艺参数对矿粒分离效果的影响。结果表明:所选用的分离工艺可有效地依据矿粒的密度和粒径进行分离。添加振动筛能大幅度降低分离产品的含杂率。分选装置的较佳参数为:筛面倾角为0°、振动频率为10 Hz、振幅为3 mm、颗粒入口底部宽度为7 mm,此时回收率96.8%,含杂率5.67%。      

毫米级颗粒在湍流场中的传热及着火特性

燃料在强湍流中的燃烧广泛存在于实际工业装置中,研究湍流脉动对燃料传热及着火的作用对准确理解燃烧过程具有重要意义.目前,对于气体燃料和液滴在湍流脉动条件下的蒸发着火等过程已经有了非常详细的研究,而对于固体颗粒受热和着火的研究,大多数试验方法,如落管炉、单颗粒炉和平焰燃烧器等,是在层流条件下进行的.湍流条件下的研究方法主要...     

Improving the recovery of coarse coal particles in a Jameson cell

It has been observed in several Jameson cell installation where the source for flotation feed is deslime screens, that the recovery of coal particles greater than 0.5 mm is not as great as that of finer material. Consequently, a research project was undertaken at a CHPP in the Bowen Basin Queensland to assess the possibility of increasing the recovery of coarser particles (+0.5 mm) within the downcomer of the Jameson cell. The effect of decreasing turbulence and agitation in a commercial-scale downcomer was investigated to assess the effect on the recovery of both coarse and fine coal particles.This paper details the findings of the test work, summarising the results relating to differences in the operating parameters within the downcomer.     

矸石似膏体充填料浆临界流速影响因素研究

为探究矸石似膏体料浆在管输过程中的流变参数的影响因素,以公格营子矿矸石似膏体充填料浆为工程背景,使用CRT流变仪测试了不同浓度、矸石颗粒粒径下的矸石似膏体充填料浆的流变参数,运用流体力学和粒状物输送水力学分析了矸石颗粒在似膏体料浆的受力情况,运用Fluent软件对管道输送过程中不同流速、矸石粒径以及料浆浓度下的料浆流动状态以及粒子运动轨迹进行了模拟验证。结果表明,矸石似膏体料浆的矸石颗粒粒径大小和浓度会影响料浆的塑性粘度和初始切应力,进而对管道输送的临界流速产生影响。具体表现为在管输过程中,矸石粒径为15mm、20mm、较5mm和10mm更易下沉,料浆浓度达到76%时,料浆初始切应力增幅会出现急剧增加,随着料浆浓度增大,管输过程中矸石颗粒更不容易沉降。     

白云鄂博稀土精矿性质及对焙烧浸出率的影响

由于白云鄂博原矿性质的不断变化,稀土精矿的性质也随之改变,从而影响后续冶炼工艺REO的收率。通过化学多元素、粒度、配分、化学物相和矿物组成分析对白云鄂博稀土精矿的性质进行了研究,并考察了粒度、REO品位、铁磷比等因素对稀土精矿焙烧浸出的影响。结果表明: 白云鄂博品位REO 53.11%的稀土精矿中主要的杂质元素为CaO、P₂O₅、F、TFe和SiO₂,REO在-30 μm粒级中分布率为90.24%,镧、铈、镨、钕轻稀土配分合量为97.89%,主要稀土矿物为氟碳铈矿和独居石;当稀土精矿的粒度变细和水浸温度、REO品位及铁磷比增加时,均有助于提高焙烧矿REO浸出率,适宜的矿酸比为1:（1.3~1.4）,适宜的铁磷比为3:1~4:1。本研究查明了白云鄂博稀土精矿的性质,为后续冶炼工艺的优化提供了理论参考依据。