The entrainment effect on the performance of iron ore reverse flotation

An iron ore mineral processing plant in Brazil treating Itabirite ore was assessed by sampling a circuit consisting of Wemco 144 mechanical cells, as part of the AMIRA P9P collaborative research project. This paper presents and discusses the results of entrainability, water recovery and quartz and hematite grades associated to hydrodynamic parameters. The results indicated strong correlation between water recovery and hematite losses which was intensified by the operating conditions of the circuit.A potential alternative to reduce the hematite losses through entrainment and to increase quartz removal was to modify the traditional circuit design to treat rougher and cleaner/recleaner tails in different stages. In addition, the scavenger residence time must be matched to the quartz floatability. Changes to design and operation of these circuits are needed to sustain concentrate recovery and grade as iron ores become finer.     

煤泥浮选过程中的细泥夹带与罩盖机理

选用开滦矿区钱家营矿的高灰难选煤泥和大同塔山选煤厂煤系高岭石,通过单矿物和混合矿物浮选试验研究了影响高灰细泥夹带和罩盖的主要因素。研究发现：影响高灰细泥夹带的主要因素为细泥粒度、起泡剂用量和矿浆浓度,捕收剂用量对其影响较小;矿浆pH值接近8时,可燃体回收率最大。EDLVO理论计算发现：微细粒的高岭石与煤粒间存在着“能垒”,当颗粒间距约为30 nm时,“能垒”达到最大值;高岭石的粒度越细,“能垒”越低。外界能量输入可以打破“能垒”,使细泥颗粒发生罩盖。试验表明：强烈的机械搅拌使混合煤样的精煤产率和可燃体回收率分别降低10.87%和13.16%。     

Modelling of entrainment in industrial flotation cells: Water recovery and degree of entrainment

Entrainment in flotation can be considered as a two-step process, including the transfer of the suspended solids in the top of the pulp region just below the pulp–froth interface to the froth phase and the transfer of the entrained particles in the froth phase to the concentrate. Both steps have a strong classification characteristic. The degree of entrainment describes the classification effect of the drainage process in the froth phase. This paper briefly reviews two existing models of degree of entrainment. Experimental data were collected from an Outokumpu 3 m³ tank cell in the Xstrata Mt. Isa Mines copper concentrator. The data are fitted to the models and the effect of cell operating conditions including air rate and froth height on the degree of entrainment is examined on a size-by-size basis. It is found that there is a strong correlation between the entrainment and the water recovery, which is close to linear for the fines. The degree of entrainment decreases with increase in particle size. Within the normal range of cell operating conditions, few particles coarser than 50 μm are recovered by entrainment. In general, the degree of entrainment increases with increase in the air rate and decreases with increase in the froth height. Air rate and froth height strongly interact with each other and affect the entrainment process mainly via changes in the froth retention time, the froth structure and froth properties. As a result, other mechanisms such as entrapment may become important in recovering the coarse entrained particles.     

KYZ浮选柱操作参数对铜浮选效率影响的研究

对秘鲁某大型铜选矿厂的铜精选作业中KYZ浮选柱的操作参数进行探索性条件试验。在不影响选厂正常生产的前提下,以充气量、泡沫层厚度和喷淋水量三个操作参数为变量条件,对比不同条件下浮选柱的选别效果,找到了与工艺流程相适应的操作参数范围。进一步得出规律,浮选柱充气量越大则回收率越高而铜品位相对降低;喷淋水的添加对浮选柱精矿中铜品位具有显著的提升作用,但对铜回收率的降低也较明显。     

煤泥浮选工艺参数对浮选指标影响的试验研究

采用XFDⅣ型浮选机对汾西紫金矿选煤厂浮选入料进行浮选试验,研究了浮选机充气量、叶轮转速和药剂配比及用量对煤泥浮选指标的影响。试验结果表明:当浮选机充气量为150 L/h、转速为1 800 r/min,捕收剂和起泡剂配比为4∶1,捕收剂和起泡剂用量分别为1 200 g/t和300 g/t时,浮选效果最好。     

脉石矿物在细粒煤浮选过程的夹带回收特性研究

以脉石矿物高岭石为研究对象,通过浮选速度实验研究了其在单独及掺配浮选条件下的回收特性,探究了起泡剂用量、浮选浓度、搅拌转速对浮选过程中高岭石回收率Rs、水回收率Rw、夹带率eg的影响.实验结果表明:单独浮选时,高岭石夹带率eg在浮选过程中基本不变,表现出"随水分配"的特征;掺配浮选时疏水性煤粒促进了高岭石回收,高岭石回...     

基于浮选柱的高灰煤泥浮选参数优化研究

阐述了高灰煤泥产生的原因及其浮选研究现状,介绍了旋流微泡浮选柱的特点及其对高灰煤泥浮选的适应性。利用实验室浮选柱试验系统,对邢台矿选煤厂高灰煤泥进行了浮选试验,并运用Design-Expert软件对试验结果进行了分析,得出最优浮选条件:捕收剂用量为2 400 g/t,入浮浓度为100 g/L,药比为8∶1,此时精煤产率为57.13%,精煤灰分为9.35%,尾煤灰分为48.63%,浮选完善指标为49.99%。     

Influence of operating parameters on the flotation of apatite

Flotation of apatite is complicated, owing to its physicochemical similarity with other minerals in phosphate ores. Despite this, relatively few studies have been done on the effect of operating parameters, such as the mode of milling, pulp conditions and collector dosage on the kinetics of apatite flotation. In this technical note, the results of batch flotation tests and the fitting of a first-order kinetic model to assess the influence of operating variables on the flotation kinetics are discussed. Pulp pH, collector dosage and pulp temperature affected recovery significantly, but the mode of milling (wet or dry) did not. All factors influenced the concentrate grade, except for the collector dosage, while the milling mode was the only factor that did not affect the flotation kinetics significantly.     

A case study of optimising UG2 flotation performance. Part 1: Bench,pilot and plant scale factors which influence Cr2O3 entrainment in UG2 flotation

In the Platinum Group Minerals (PGM) industry, almost all UG2 deposits being currently developed are deep level and bankable feasibility studies must rely entirely on batch testwork of borecore samples. Since UG2 has a significant chromite (FeO·Cr₂O₃) content, minimising chromium oxide (Cr₂O₃) recovery into final concentrate has become a critical aspect of downstream smelting since % Cr₂O₃ in furnace feed has a practical upper limit of about 2.5%. In most cases concentrate is toll smelted but penalties are severe depending on chromite content. Together with PGMs, the characterisation of chromite floatability and prediction of recovery and concentrate grade in a production plant using bench-scale data is therefore a key component of UG2 ore analysis. The need to accurately predict chromite recovery and particularly to identify characteristics that indicate when % Cr₂O₃ in concentrate can be reduced has a significant impact on the project’s financials and subsequent plant design.The natural floatability of chromite is low and its passage into concentrate is almost entirely by entrainment in water carry-over into concentrate whereas PGMs are recovered by true flotation. Optimising flotation performance has to accommodate these two completely different flotation behaviours in an effort to reject chromite whilst at the same time maximise Platinum Group Minerals (PGM) recovery and grade.Incorporating extensive testwork conducted by Barrick Platinum South Africa and Northam and other plant data, the paper traces chromite, and to a lesser extent PGM, floatability in bench, pilot and plant scales and highlights that certain mechanisms of chromite entrainment are consistent irrespective of cell size and efficiency.     

Influence of coal particles on froth stability and flotation performance

Solid particles have significant effect on flotation froth. In this research, the effects of coal particles of different size and hydrophobicity on froth stability and flotation performance were studied. The froth stability was measured in both the froth formation and froth decay processes by maximum froth height, froth half-life time and water recovery. The results show that fine particles of moderate hydrophobicity contributed most to maximum froth height in the froth formation process and were most favorable for flotation. Fine hydrophilic particles stabilized the froth in the froth formation process but the froth half-life time was very short due to the high water solid ratio. High hydrophobic particles of both fine and coarse size fractions greatly increased the froth half-life time in the froth decay process. But the froths were very rigid and the maximum froth heights were very low. The presence of fine hydrophobic particles was very unfavorable for the recovery of coarse particles.     

微乳型捕收剂的稳定性和浮选性能的试验研究

微乳型捕收剂(Micro-emulsion Collector,MEC)在煤浆中的分散性能优于柴油和乳化柴油,可以有效降低煤泥浮选药剂的用量。MEC的稳定性是影响其工业应用的重要性能指标,国内外学者通常采用静置观察法研究乳化柴油和微乳化柴油的稳定性,难以直观并定量表征微乳液的稳定性和液滴粒径。笔者借助多重散射光稳定性分析仪研究了乳化剂配方和用量、超声波功率及作用时间对MEC稳定性和液滴粒径大小的影响,通过煤泥浮选试验考察了MEC的浮选性能。研究结果表明:制备MEC的最佳工艺条件为,乳化剂用量为柴油质量的5%,含水量为柴油质量的5%,表面活性剂配方为Span80∶Tween40∶Octanol=7∶3∶4,磁力搅拌10 min后用200 W超声波强化处理5 min;乳化剂配方和用量影响MEC的稳定性和液滴粒径大小。乳化剂用量越多,MEC越稳定。乳化剂用量为3%时,液滴易发生聚集,放置一段时间后液滴粒径会超过100 nm。乳化剂用量为7%时,MEC最稳定,液滴初始粒径为69 nm,并随放置时间延长缓慢变大。乳化剂用量为5%时,MEC稳定性好,液滴粒径随放置时间的延长基本不发生变化,保持在37 nm左右;超声波功率低于600 W时,功率越小,MEC越稳定。功率大于600 W时,功率越大,液滴粒径越小,MEC稳定性越好。超声波处理时间为20 min时,MEC的稳定性动力学指数(Turbiscan Stability Index,TSI)值随放置时间延长快速变大,MEC很不稳定;MEC用于煤泥浮选时,能显著提高煤样的接触角,增加煤粒表面疏水性,提高煤粒的可浮性。在相同的捕收剂用量下,浮选精煤产率更高,灰分更低,浮选完善指标更好。     

Effects of the rock mass parameters on the dragline excavation performance

This paper investigates impacts of rock mass properties on dragline performance. Performances of two draglines operated in different rock formations in Tuncbilek Coal mines were analyzed using modified geological strengths index (GSI). Results showed that draglines’ performance change with the rock mass properties. Based on the available data, an empirical relationship was generated to estimate dragline production capacity. The estimated excavation amount by the proposed model was found to be consistent with the excavation amount obtained from the field data.     

高强度调浆对微细粒磷灰石浮选效果的影响研究

为了提高微细粒磷灰石的浮选指标,需要对入浮矿浆进行高强度调浆处理。本文以承德某地的斜板浓密溢流为研究对象,展开高强度调浆工艺条件试验。以实验室30L规格的高强度调浆机和工业上2m直径的高强度调浆机为研究手段,对调浆时间、调浆转速等展开条件试验。30L调浆机结果表明最佳的浮选时间为6分钟,最佳的线速度为8.35m/s,和普通改质机叶轮和直桨叶轮相比,新型叶轮的调浆效果更好,并且能耗较低。2m高强度调浆机的工业试验表明,150rpm是最佳的转速。并且和普通调浆机相比,在相同产率（粗选产率为5%~10%）下磷灰石的回收率提高了约10%,可见高强度调浆机能显著改善细粒磷灰石的浮选环境。清水条件高速摄像和浊度测试结果表明,高强度调浆机叶轮和普通搅拌槽叶轮相比,对油滴的分散效果更显著,搅拌后形成的乳浊液体系更为稳定。     

基于Canny算子的浮选气泡形态特征参数提取

浮选过程中微观气泡的形态特征参数对浮选条件实验及机理研究具有重要意义,本文提出了一种基于气泡区域选取及Canny边缘检测的气泡形态特征提取的方法。首先,将拍摄到的浮选气泡图像进行预处理操作,阈值分割后的二值图像与原图像矩阵相乘得到气泡区域图像;然后利用Canny边缘检测提取气泡边缘坐标参数,基于此坐标信息计算出气泡面积、周长、圆心位置等参数,并实现向物理参数的转换。结果表明,此参数提取方法鲁棒性强、精度高,适用于光照不均和噪声干扰等复杂环境下气泡形态特征参数的提取。     

煤炭浮选机性能优化研究

针对梁北选煤厂XJX-T12型浮选机存在的处理能力不足、电能消耗大、搅拌电机故障率高、电机维修困难等问题,重点分析了XJX-T12型浮选机的入料形式、搅拌机构以及搅拌电机的安装方式等关键环节,并结合XJM-S12浮选机的特点,对现有的XJX-T12浮选机进行了改造。改造后提高了浮选机的处理量、降低了电能消耗及搅拌电机的维修强度,使浮选机的性能大幅度提升,取得了良好的经济和社会效益。     

铝土矿浮选新型捕收剂的捕收性能及机理研究

通过一水硬铝石和高岭石的单矿物浮选试验、接触角、红外光谱、和ζ电位测量分析了东北大学研制的DJL-1和DJL-2捕收剂在铝土矿正浮选中的浮选行为和作用机理。一水硬铝石与DJL-1和DJL-2作用后接触角变大、疏水性变强;高岭石与DJL-1作用后接触角几乎不变,与DJL-2作用后接触角变大。DJL-1使一水硬铝石和高岭石表面ζ电位均负向增加,DJL-2对一水硬铝石和高岭石表面ζ电位影响较小,分别使用DJL-1和DJL-2,一水硬铝石和高岭石的最大回收率之差为54.5%和70.5%,DJL-2在更宽的温度和pH范围内获得更好的浮选结果;DJL-1和DJL-2在一水硬铝石表面存在键合吸附和氢键作用,DJL-1与高岭石表面存在氢键作用。结果表明,DJL-1和DJL-2均是铝土矿正浮选的优良捕收剂,且DJL-2更优。     

磁化煤油-AEO9 捕收剂的性质及其浮选效果研究

针对低阶难浮煤泥浮选过程中煤油消耗量大、浮选效果差等问题,用自制磁化装置,以煤油-AEO9捕收剂为研究对象,首先考察不同磁化温度、磁场强度和磁化时间对捕收剂的性质的影响,然后进行煤泥浮选实验,考察其对煤泥浮选效果的影响,最后进行磁化前后的对比实验.结果表明:磁化条件可以有效降低煤油-AEO9捕收剂的表观黏度和表面张力,且都呈先降低后升高的趋势.磁化处理后的捕收剂用于煤泥浮选的效果得到明显改善,捕收剂的较佳磁化条件为磁化温度25～30℃,磁场强度0.3 T,磁化时间6min,浮选精煤产率、尾煤灰分和可燃体回收率分别提高了 10.56％、10.36％和11.74％.     

磨矿介质对两种铜镍硫化矿石浮选行为的影响研究

磨矿作业对矿物浮游性及浮选分离有重要的影响。本研究以分别产自中国和南非的两种不同铜镍矿为研究对象,研究了磨矿介质种类对铜镍矿石浮选行为的影响。研究结果表明,磨矿介质种类对两种矿石中铜镍矿物浮选回收率、浮游速度和脉石矿物的浮选行为的影响规律并不相同,且与报道中纯矿物体系中磨矿介质的影响规律不完全一致。与铸铁介质磨矿相比,采用不锈钢球介质磨矿后,中国铜镍矿混合浮选硫化铜浮游速度更快,可以获得较高的铜、镍品位,混合精矿中脉石含量显著降低。南非铜镍矿经铁介质磨矿后的铜、镍回收率高于惰性介质磨矿。两种矿石的矿物组成差异可能是磨矿介质对其浮选行为影响规律存在差异的主要原因。     

Optimizing flotation bank performance by recovery profiling

This paper uses the first-order fully mixed model to argue that operating a bank of cells with a flat cell-by-cell recovery profile yields maximum separation between two floatable minerals with constant relative floatability for a target bank cumulative recovery. The bank optimization problem thus translates into a local problem of selecting cell manipulated variables, such as air rate, to reach that recovery profile. Some properties of the bank that emerge from the analysis are discussed. Recovery profiling appears to contribute to the success of air profiling recently reported.     

Effect of particle size on flotation performance of complex sulphide ores

Flotation processes occurring in the bulk and froth phases have a characteristic influence on the structural features and dynamics of the flotation froth. It is recognized that the structure and texture of a mineral froth is a good indicator of flotation separation performance. The surface froth feature and dynamics are presented by three features extracted from the digitized images of the froths, i.e. SNE, a rough indication of the average bubble size of the froth, froth stability and the average grey level of the froth, an indication of mineral loading. Particle size is an important parameter in flotation operation. Nowadays, particle size is often measured and controlled in flotation concentrators. In this study the dependence of the froth structures on the particle size variation was investigated on the batch flotation of a sulfide ore from the Merensky reef in South Africa, and the size by size recovery curves were studied as well. In general medium particles produced bubbles smaller than those observed in the presence of fine and coarse particles, and the recovery rates were larger. Entrainment was a contributory mechanism to the recovery of fine particles. The fluctuation of flotation indices on the particle size change can be diagnosed and predicted by the froth structures change with a high degree of accuracy.