浮选过程泡沫图像特征识别研究

在浮选过程中,通过观测矿浆泡沫状态来判断药剂添加量的程度。运用图像检测方法,提取矿浆中泡沫图像特征,获取浮选过程加药量的程度,实现加药量进行调节,浮选过程加药量的自动控制提供条件。     

Competitive representations in studies on froth flotation and prospects of their application for selection of reagents

From the viewpoint of experimental substantiation and usefulness for the selection of reagents for froth flotation, five different representations are considered that interpret the causes of selective capture of particles by bubbles. These are the hysteresis, electrostatic, capillary, jointly radiographic and luminescent, and sophistic presentations, which were popular in the past, then rejected, and now are being developed again; they, however, contain substantial errors. Quantitative analysis has shown us that capillary presentations are preferential, with the use of which it proved possible to establish the effect that the electrical charge of the particle surface (or the ionic composition of the pulp) had on the absorption of neutral organic molecules on the surface; to determine the nature of forces that keep the particles on the bubbles; to find the interlayer of the liquid between the bubble and the substrate; to determine the properties of thin layers of the liquid, which are the “glue” keeping the particles on the bubble; to reveal the structure of the boundary layers of the liquid that are in contact with the solid and gas phases; to introduce the quantitative criterion of nonequilibrium for the characteristics of the properties of reagents, which manifest themselves in the dynamic conditions of froth flotation and, the most important, which are based on capillary physics, in order to calculate various models of froth flotation to reveal their mechanism and the causes of existence; to find the optimal conditions for solving concrete problems and the modes of conducting reagent-free, ecologically pure froth flotation. It is also important that the capillary representations allow one to easily recognize the incorrectness of not only the previously wide-spread popular (sophistic) hypotheses, but certain modern ones as well.     

Development of investigation techniques of froth flotation from the beginning of its wide industrial use. Part two. Methods of evaluation of the adsorption and orientation of heteropolar molecules of reagents in the adsorption layer on the surface of particles

Methods for evaluation of the adsorption and orientation of heteropolar molecules of reagents in the adsorption layer on the surface of particles and the adsorption of reagents on the surface of bubbles are considered. Experiments of nonfrothing flotation from a turbulent medium, methods of froth flotation (FF) with a limited air consumption, measurement of detachment forces simulating the FF, determination of the adherence times of the particles to the bubbles, and measurement of the contact angles can be used to reveal the character of the orientation of adsorbed molecules or ions of reagents. To evaluate the adsorption of reagents on the surface of bubbles, only static procedures for determination of the surface tension (σ), methods of recording the relaxation curves σ(t), and methods for evaluation of froth formation and destruction can be used. This possibility is reviewed to establish the relation between the definite properties of reagents and their concrete effect under the dynamic FF.     

Effect of Oleic Acid on Froth Properties and Reverse Flotation Performance of Thermal Coal

Reverse flotation was proposed as a potential method for the upgradation of low rank thermal coal. Higher combustible matter recovery in the float could be obtained using reverse flotation method compared to conventional flotation method. In order to reduce the entrainment of fine particles, oleic acid (OA) was used as froth regulator in coal reverse flotation process. Experimental data showed that the total volume of froth product in the absence of OA was almost 3 times more than that in the presence of 0.45 kg/Mg OA dosage. Reverse flotation results showed that the ash content of froth product increased with the increase of OA dosage which indicated that the entrained coal particles could be decreased by the addition of froth regulator OA.     

Investigation of froth flotation and selection of reagents on the basis of the mechanism of their effect: Report 1. Substantiation of the selected methods for investigation of the process

Three strengthening components of the particle-bubble contact that emerges under the effect of appearance of the external detachment force f in the dynamic conditions of froth flotation are considered. These are the flexure of the bubble surface at the contact perimeter, the increase in the contact angle θ, and the local increase in the surface tension σ on the bubble surface near the perimeter of its contact with the detached particle. Using the equations of capillary physics and experiments, three possible mechanisms of flexure of the bubble surface (which are caused by the effect of gravitation and reagents, namely, classical, hysteresis, and capillary mechanisms) are revealed. The necessary properties of reagents, which promote such flexure under the effect of f, are established. These are their ability to selective hydrophobization of the particle surface and to the local increase in the surface tension σ on the stretched bubble surface. Two groups of simple methods are recommended to investigate the process and to select reagents which model the process of froth flotation: (i) to evaluate the ability of reagents to vary the wettability of the particle surface—flotation experiments in frothing and nonfrothing apparatuses and to measure detachment forces, the time of adherence of the bubbles to the particles, and contact angles; (ii) methods for recording the relaxation curves and evaluating frothing properties (for reagents acting preferentially on the bubble surface). The effect of the capillary pressure of the gas in variously sized bubbles on the value of detachment forces of the particles from them, as well as the invariance of these forces of σ during slow detachment, are shown.     

Recent developments and advances in formulations and applications of chemical reagents used in froth flotation

Over the last two decades, significant advances have been made in the field of chemical reagents used in froth flotation, a solids separation technique whose success depends on the use of a wide variety of both inorganic and organic reagents, including polymers, for controlling the wetting behavior of solid surfaces, particle dispersion or aggregation, and bubble stability. Novel discoveries include new chemistries of reagents, especially collectors, depressants and frothers, new blends of known chemical compounds, new applications of known reagents, and the development of scientific methodologies for reagents design and testing of potential formulations. Even though the most important application of froth flotation has been the processing of raw materials, in recent years new applications of flotation continue to grow. Depletion of easy-to-process, high-grade ores and an increasing demand for clean technologies require new flotation reagents, that are environmentally friendly, more versatile, and economic. This article reviews recent developments of new chemistries for froth flotation, some of which are now available as commercial products, and their applications.     

Effect of Froth Structure and Mobility on Plant Performance

Abstract

The role of processes operating in the mineralised froth encountered in production scale flotation machines is discussed in relation to both process operation and mathematical modelling techniques used for simulating process response on complex process flowsheets. The structure of froths (and associated drainage patterns) developed on a continuously operated flotation cell over a wide range of operating conditions is reported. The concept of shear induced drainage in the froth is introduced, where mobility in froths on producing cells is seen to reduce froth separation effects. The relation of shear induced drainage to modern cell design is discussed, particularly in terms of maximising froth separation effects to enhance process separation efficiency.     

Investigation into the froth flotation and selection of reagents on the basis of the mechanism of their action: Report 2. A comparison of flotation properties of millimeter,micrometer, and nanometer bubbles based on equations of capillary physics part one

Calculations with the application of equations of capillary physics (ECP) showed that the capillary pressure in the bubbles with a diameter from 3 mm to 5 nm varies from several thousandths to several hundreds of atmospheres and affects the processes associated with froth flotation. It is shown that bubbles 2 μm in diameter can spontaneously (i.e., with a decrease in energy) adhere to a solid surface, and this tendency increases in an antibate manner as their size decreases, which is the main factor. The reality of such a mechanism is confirmed by the multiyear practice of applying the Potter-Delprat process. In connection with the aforesaid, when investigating the flotation process, it is more rational not to orient for the principle of “effective collisions” of particles and bubbles as a necessary condition for their adherence and flotation, but to apply the ECP. This approach is more productive.     

浮选过程中颗粒--气泡黏附作用机理及研究进展

系统分析总结了浮选过程中颗粒与气泡的黏附概率模型、EDLVO理论、颗粒-气泡集合体的受力分析、影响因素分析和颗粒-气泡黏附的研究进展.基于接触时间、感应时间的方法和能量势垒的方法,分别从动力学和热力学的角度分析总结了黏附概率模型,并从动力学和热力学的角度解释了颗粒大小、气泡大小、颗粒疏水性、颗粒表面粗糙度和溶液pH对黏附概率的影响,对静态环境和湍流环境中颗粒-气泡集合体进行了受力分析,颗粒和气泡的黏附力有毛细作用力、液体静压力和浮力,静态环境中的脱附力只有重力,但是湍流环境中的脱附力还包括振荡力和离心力.很多研究学者利用先进的仪器和检测手段对颗粒-气泡的黏附做了大量的研究,取得了大量研究成果.颗粒-气泡黏附作用过程相当复杂,试验研究时简化了作用条件,目前理论不能满意解释黏附过程,需要结合实际进行更深层次、更全面的研究.      

FP-01浮选泡沫图像处理系统

比较了国内外图像处理技术在浮选过程中应用的三个代表性例子 ;介绍了FP - 0 1浮选泡沫图像处理系统 ;指出了图像处理技术在浮选过程控制中的应用前景。     

Effect of Clay Slime on the Froth Stability and Flotation Performance of Bastnaesite with Different Particle Sizes

Russian Journal of Non-Ferrous Metals - To investigate the effect of kaolin particles on the flotation performance and froth stability of different particle sizes of bastnaesite, batch flotation...     

基于泡沫视觉特征的浮选精矿品位的软测量

针对矿物浮选在线检测X荧光分析仪缺失、人工检测严重滞后的问题,依据泡沫视觉表面特征对浮选精矿品位具有直接指示作用的原理,采用最小二乘支持向量机(Least Squares Support Vector Machine,LS-SVM)实现浮选精矿品位的软测量。工业运行数据仿真结果表明,建立的软测量模型能够实现精矿品位的预测精度,满足工业要求。     

浮选泡沫图像处理技术研究现状与进展

简述了浮选泡沫图像处理系统国内外的研究现状,以及图像处理技术在泡沫浮选中的作用及重要意义.主要介绍了近年来国内外对浮选泡沫图像的各种处理技术的研究概况.并根据研究现状预测了浮选泡沫图像处理技术的应用前景.     

Interactions between a Small Bubble and a Greater Solid Particle during the Flotation Process

ABSTRACT

The interaction between bubbles and solid particles is an important mechanism in many industrial processes and flotation is a significant component of the most utilized applications. While flotation of mineral ores deals with fine particles and larger bubbles, the aim of this review is to focus on the opposite case; the interaction between smaller bubbles and larger particles encountered mostly in plastic flotation. Plastic flotation seems to be one of the appropriate methods for separating plastics, which is necessitated by increasing plastic consumption and the growing need to recycle. The first part of the article focuses on the problem of the collision of a bubble with a particle, both spherical and planar. The collision efficiency is discussed. The second part is devoted to the problem of liquid film rupture and the creation of the three-phase contact line. The third and final part focuses on the problem of the three-phase line expansion and the effect of surfactants on the resulting bubble stability.     

降低包头白云鄂博稀土精矿成本新工艺研究

在如何降低稀土精矿浮选成本方面进行了探索。将生产中所用的稀土浮选原料强磁中矿更换为强磁扫选精矿的反浮泡沫,不需特别的脱药措施,只采用稀选车间现有的工艺流程和浮选药剂组合方案,即可获得所需的稀土精矿,使每吨稀土精矿的成本降低一半左右。同时,还对从混合泡沫中分选稀土精矿的捕收剂作用机理进行了探讨。     

Numerical simulation of froth formation in aerated slurry coupled with population balance modelling

A computational fluid dynamic (CFD) model has been developed to incorporate pulp and froth zones into one model. In the present research, froth was considered as a separate phase comprised of a mixture of gas, liquid and solids. Considering the froth phase as a separate phase, allowed the incorporation of pulp and froth zones into one model by tracking the formation and destruction of the froth phase due to mass exchange between the pulp and froth. Bubble break-up and coalescence were taken into account in the pulp zone, by employing user functions, written using FORTRAN. The effect of bubble coalescence process due to ?lm rupture was considered in the froth phase. The variation in the concentration of attached particles due to attachment and detachment processes were also taken into account. The CFD model predicted the height of froth layer, the concentration of different bubble sizes in both pulp and froth zones, and finally the multiphase ?ow phenomena in the slurry column. Froth height was found to increase with the increase of gas flow rate while increasing solid concentration decreased froth height.     

Recovery of Fine and Ultrafine Mineral Particles by Electroflotation – A Review

Fine and ultrafine particles are successfully recovered by flotation when fine bubbles are present. Electroflotation is a technique in which fine bubbles are generated by the electrolysis of water. This article reviews the experimental studies into mineral recovery by electroflotation and the potential application of electrolytic bubbles in the recovery of fine and ultrafine mineral particles. The literature reveals that electroflotation resulted in better recoveries of ultrafine particles (e.g. dolomite, magnesite, and pyrite) as compared with dispersed-air flotation because electrolytic bubbles are smaller in size and are more active than those generated during dispersed-air flotation.     

浮选机空气流量自动控制实践应用

城门山铜矿5000T选矿厂选用了北京矿冶研究院设计的KYFⅡ-50浮选机,此浮选机叶轮不起吸气作用,空气靠外部风机强制吹入。在选矿过程中采用先进仪表,对KYF浮选机空气流量进行测量、调节和控制,实现浮选充气量自动控制,使进入浮选槽内空气量和分散度达到最佳化,有效地提高气泡与矿粒的接触率,稳定选矿指标。     

Coal Flotation in Saline Water: Effects of Electrolytes on Interfaces and Industrial Practice

ABSTRACT

Coal preparation plants are increasingly turning to alternative sources of water to reduce their consumption of fresh water. These alternative sources can vary significantly in ionic content. This review discusses the effect of dissolved inorganic electrolytes on coal flotation. It is argued that increasing process monitoring will enable a better understanding of the effects of salts on the flotation process. A pragmatic approach in monitoring is essential to differentiate significant factors from insignificant ones controlling the performance of coal flotation units in salt water. The effects of inorganic electrolytes on the air–water interface and the solid–liquid interface are reviewed to assist in the interpretation of industrial results.