超声乳化煤油乳滴尺寸对泡沫性质及隐晶质石墨浮选的影响

本文提出采用乳化煤油的方法强化泡沫排液,改变泡沫性质,从而降低在隐晶质石墨浮选中脉石颗粒夹带的思路。将乳化剂、煤油和氯化钠溶液以2.5%、2.5%和95%的比例通过不同的复配方法混合,采用超声波处理制备出不同乳滴尺寸的乳化煤油,并探究了不同方法获得的乳化煤油对泡沫性质(如气泡尺寸、泡沫层高度和水回收率)和隐晶质石墨浮选过程中脉石矿物夹带的影响。研究结果表明:随着乳化煤油乳滴尺寸的减小,泡沫层高度和水回收率降低,隐晶质石墨浮选过程中脉石矿物的夹带量减少,浮选精矿品位和回收率均提高。     

浮选泡沫细粒脉石夹带与充气量的关系

为更好地揭示并合理利用浮选过程中细粒脉石的泡沫夹带与充气量的内在联系,采用自制的泡沫特性测试系统,模拟了浮选中充气量对泡沫的特性及脉石的泡沫夹带行为的影响规律。结果表明：在两相体系中,充气量的增大会明显降低泡沫层中气泡的兼并速度,增大泡沫的含液率及泡沫柱表观液流速度,显著提高泡沫水回收速率;在三相体系中,充气量的增大会显著降低泡沫中脉石的回流速度,显著提高顶部泡沫层的脉石质量分数。因此,在浮选过程中,在保证精矿有效回收的前提下,控制充气量是有效控制精矿泡沫夹带脉石的有效手段。     

浮选泡沫相中现象及机理研究进展

泡沫相(层)是浮选重要组成部分之一,决定了最终精矿品位和整体浮选效率。由于泡沫相中的气泡与颗粒的相互作用比较复杂,近些年国内外学者围绕浮选泡沫层开展了大量相关研究。本综述在介绍浮选泡沫的结构和性质后归纳了浮选泡沫失稳的机理,即排液、粗化和兼并在现阶段的研究进展。对颗粒强化泡沫稳定性的相关机理进行了分析和总结,且归纳出颗粒疏水性、粒度和形状是颗粒影响泡沫层稳定的主要因素。之后回顾了泡沫层中常见的泡沫夹带现象,分析总结了泡沫夹带的三个主要机理;颗粒物理性质、水回收率、湍流强度、矿浆浓度、泡沫层性质和表观气速是影响泡沫夹带的主要因素;夹带模型的建立对脉石夹带程度的有效预测以及浮选工艺流程的优化具有重要意义。最后提出在今后的研究中加强泡沫相流体力学研究和推进泡沫层颗粒追踪技术是浮选泡沫相研究的方向之一。     

脉石矿物夹带进入浮选泡沫过程的研究

浮选泡沫的结构和运动决定着夹带集到精矿中的脉石数量，尽管这一现象对总的工艺指标起着重要的作用，但现阶段对泡沫的性状仍然了解得不够，至今为止，已建立出的多数用以说明夹带过程的模型都是经验模型。本文介绍了一种有重要参考意义的理论模型，并试图利用这一模型更好地了解夹带现象，这种通用的泡沫模型器（UMIST Froth-Sim）可以模拟很宽范围的浮选条件，因为它考虑到了出现出浮泡沫中的许多物理现象，该模型首先要根据重力，黏滞力和毛细效应描述气体的运动，气泡的兼并和水的运动。根据疏水性，颗粒粒度和密度区分不同固体着型之间的固体运动，并建立包括几何普拉特奥边界（Plateau bordey)的扩散，颗粒沉降和水运动等效应的模型，本文的目的是要证明，这一模型在解释试验观测到的脉石矿物的夹带和捕收现象的应用中的可能性。这是通过对比模型预测的脉石回收率和试验观测到的脉石回收率与水回收率之间关系实现的。     

无机盐对气液两相泡沫特性的影响研究

为更好地揭示并合理利用浮选过程中无机盐对浮选泡沫特性的影响,采用自制的泡沫特性测试系统,通过对两相泡沫不同高度处泡沫的静压强、气泡直径、泡沫柱的溢流流量进行测定,深入研究了无机盐对泡沫特性参数的影响规律.结果表明:在两相体系中,NaCl、Na2SO4、MgSO4及AlCl3这四种无机盐可显著减小各泡沫层高度下的气泡直径,增大泡沫含液率以及泡沫柱表观溢流速度,从而增大微细粒亲水脉石的泡沫夹带,而NaClO3的添加对泡沫特性参数均无显著影响.     

起泡剂对硫化矿浮选的影响

研究了起泡剂MIBC、BK201、松醇油及2-乙基己醇对石英及黄铁矿单矿物浮选行为的影响, 并进行了实际矿石浮选试验。单矿物试验结果表明: 石英通过泡沫夹带进入浮选精矿, 而黄铁矿通过疏水上浮和泡沫夹带的双重作用进入浮选精矿。不同起泡剂作用下, 精矿中泡沫水回收率越高, 石英和黄铁矿的浮选回收率越高, 不同起泡剂对石英和黄铁矿具有不同的夹带效果, 使石英和黄铁矿浮选回收率最高的起泡剂分别为BK201和MIBC。实际矿石浮选试验表明: 浮选产率、精矿品位及回收率与泡沫水回收率密切相关, 泡沫水回收率增大, 精矿产率增大, 而品位降低。选择合适的起泡剂能够增加硫化矿物的回收率并降低石英的回收率, 获得较好的浮选分离效果。     

优选药剂制度优化精矿品位和回收率

在选择和优化浮选药剂制度后,就有可能从布什维尔德杂岩的UG-2矿带中回收铂族金属和金(PGM Au).UG-2矿石的特点是有两种主要的脉石相(即铬铁矿和硅酸盐矿物),它们具有明显不同的物理和化学性质.设计了一种策略,以便在提高精矿品位前提下,可降低脉石的回收率而不会明显影响有价组分的回收率.由于PGM Au作为具有不同化学和物理性质的多种不同矿物产出这一事实,使有价组分的回收变得复杂,因此操作上就必须考虑到有价矿物的特征和最大限度回收,并满足严格精矿质量要求.进行了实验室试验,以查清各种浮选参数的影响.讨论了发生于浮选槽中的各种机理.本文证明了回收有价组分和脉石时夹带的重要性,更好地了解了这种非选择的子过程在整个回路控制中的作用.     

脉石矿物机械浮选过程中控制因素的评述及分析

本文对脉石矿物的机械浮选过程进行了评述，首先考虑了有关脉石矿物输送的机理，阐述了水的回收率及其它主要因素对脉石矿物的影响，并介绍了脉石矿物的分级及夹带的数学模型，对泡沫特性的重要性也进行了讨论。文章中介绍了一种估计浮选回路中脉石矿物夹带的分析方法，并确定了制约脉石矿物机械浮选的一些措施。     

矿物浮选泡沫图像处理技术的发展——《矿物浮选泡沫图像处理与过程监测技术》

正选矿是矿产资源加工中必不可少的一个重要环节,泡沫浮选是重要的一种选矿方法,广泛应用于钢铁、有色金属、煤炭、化工和环保等领域。泡沫浮选是通过在矿浆中加入浮选药剂,并充入空气搅拌产生气泡,根据矿物表面润湿性差异,疏水有用矿物在气泡上黏附,亲水脉石矿物滞留水中,实现有用矿物与脉石分离的一种分选方法。浮选泡沫表面视觉特征     

煤泥盐水浮选技术

盐水对浮选体系下颗粒与气泡行为的影响规律进行了综述。浮选矿浆中的无机盐电解质在提高精煤可燃体回收率的同时也增加了脉石矿物的回收。反电荷阳离子在煤粒表面吸附改善颗粒疏水性,颗粒-气泡间的液膜排液速度因双电层被压缩而加快;同时电解质兼有起泡剂的效果,能有效阻止气泡兼并聚合。另一方面,盐水浮选体系下细粒脉石颗粒的水流夹带和聚合截留现象严重,可燃体回收与脉石颗粒非选择性上浮之间的矛盾激增。     

Investigating the effects of particle shape on chromite entrainment at a platinum concentrator

In flotation, entrainment is undesirable as it results in the recovery of hydrophilic gangue particles which reduces the concentrate grade. For UG2 ore, a South African platinum group mineral (PGM) ore, entrainment is particularly problematic because it leads to the recovery of chromite in the final concentrate which can cause severe problems in the smelter. It is therefore important to understand all factors affecting entrainment. These factors include froth characteristics, as well as particle size distribution and density, which have been studied widely. Theoretically, they should also include shape, as shape affects drag coefficients of particles and thus hindered settling rates of particles within plateau borders. In this study, detailed mineral-specific shape characterisation with Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) was used to assess the effect of particle shape on chromite entrainment during flotation of UG2 ore at a South African platinum concentrator. This plant-scale study suggests that shape does affect entrainment, with more rounded particles showing higher entrainment than angular, elongated particles.     

Effects of frother type and froth height on the flotation behaviour of chromite in UG2 ore

About 70% of the UG2 reef consists of the gangue mineral chromite (FeO · Cr₂O₃). In the processing of UG2 ore by flotation for the recovery of platinum group elements (PGEs) the presence of chromite in the concentrates can cause serious downstream processing problems and a grade of less than 3% Cr₂O₃ is sought. This constrains operating procedures and compromises optimum recovery of the PGEs.In this study, the influence of the froth phase on the recovery of chromite was investigated by changing both frother type and dosage and froth height in batch scale flotation tests. The results obtained showed that it was possible to obtain concentrates with less than 3% Cr₂O₃ content by increasing the froth height, allowing for better drainage of both entrained gangue particles and coarse particles with low hydrophobicity. At a 3 cm froth height, very low water and mass recovery were obtained and thus low entrainment. Nevertheless a small amount of chromite particles coarser than 45 μm was persistently recovered which may be attributed to the true flotation of these particles.The mechanism of chromite recovery was discussed on the basis of the difference in the appearance of the froth structure and water recovery.     

Flotation frother mixtures: Decoupling the sub-processes of froth stability,froth recovery and entrainment

The flotation process consists of two distinct phases: the pulp and froth phase. One of the main roles of the froth phase is to create a suitable environment for the separation of floatable, valuable minerals from non-selectively recovered, entrained gangue minerals. As a result the froth phase plays a significant role in the metallurgical performance of industrial flotation cells. Froth stability is important for the recovery of valuable minerals. However, a stable froth may contribute to increased entrainment and, consequently, a lower grade.This study compares the effect of frother mixtures with that of their single component frothers on the froth stability, froth recovery and entrainment of a platinum-bearing UG2 ore using polyglycol and alcohol frothers. The study showed that frother mixtures resulted in a greater froth stability than either of their component frothers. The increased froth stability was reflected in increased froth recoveries and greater overall recoveries. However, the important aspect in the use of frother blends was that they altered the froth structure and resulted in a lower degree of entrainment. This, together with the increased recovery, resulted in higher grades of valuable mineral recovered to the concentrate when using the frother mixtures.     

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.     

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.     

粗细粒级差异化给矿对浮选柱选别性能的影响

粗细粒级矿物具有不同的浮选特性,浮选柱主要应用于精选作业的细粒级矿物分选,对粗颗粒矿物回收率较低,限制了浮选柱的应用。在泡沫层分选理论的基础上,以纯石英矿物(纯度大于99%)为代表矿样,将其分成150~280μm和-15μm粗细粒级两个组分,采用Ф100 mm×2 000 mm浮选柱开展试验考察粗细粒级差异化给矿对选别性能的影响。在一个试验中将粗细粒级矿物混合给入浮选柱泡沫层之下进行常规浮选,在另一个试验中将粗细粒级矿物差异化给入浮选柱泡沫层之上和泡沫层以下分别进行泡沫层分选和常规浮选。试验对比结果表明,粗细粒级差异化给矿提高了浮选柱精矿回收率,对粗颗粒矿物回收效果提升更为显著。