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1992 | Buch

Innovations in Flotation Technology

herausgegeben von: P. Mavros, K. A. Matis

Verlag: Springer Netherlands

Buchreihe : NATO ASI Series

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Über dieses Buch

The present book is the outcome of an Advanced Study Institute meeting, which was held in Kallithea, Chalkidiki, in Northern Greece, from 12-25 May 1991 and attended by 69 delegates from 18 countries. The Institute brought together scientists, engineers and technologists currently involved in basic and applied research on the different aspects of flotation. The Institute covered subjects in four major areas of flotation: a) fundamentals; b) chemical technology aspects; c) mineral processing; and d) water and wastewater treatment. Apart from the papers reproduced in this volume, several short oral communications were also presented. Participants also had the opportunity to visit the Hellenic Chemical Products & Fertilizers Co. Ltd. mixed sulphides plant, in Chalkidiki. Conference participants, whose interest and research projects are in this broad field of science and engineering, provided a well-informed discussion of the problems encountered, as well as possible directions of future technological developments. It is hoped that this book is not only a good record of the presentations made (formal and informal), analyzing the state-of-the-art in flotation, but will also be helpful for students, scientists and technologists working in the fields of separation processes and in particular mineral processing and wastewater engineering. All the invited speakers and the participants made this summer school possible, worthwhile and enjoyable. The sponsorship by the NATO Scientific Affairs Division is gratefully ack­ nowledged. The Editors would like to thank the members of the Organizing Committee, Dr. B.A.

Inhaltsverzeichnis

Frontmatter

Fundamentals

Frontmatter
1.1. The Study of Thin Aqueous Films as Models for Froths and Flotation
Abstract
Thin liquid films play a significant role as basic structural elements of many disperse systems (foams, froths, emulsions, etc.) as well as in processes of major industrial impor- tance, such as flotation. The stability of thin liquid films from aqueous surfactant solutions is of primary interest for froth generation as well as the contact formation between air bubbles and mineral particles.
The importance of thin aqueous films as models for studying the fundamental behaviour of these mineral processing operations is discussed. The characteristic properties of the aqueous film is described and the experimental techniques developed to measure film thickness, stability and intermolecular interactions are reviewed.
R. J. Pugh, E. Manev
1.2. The Mechanisms of Collector Adsorption-Abstraction (Ionic and Non-Ionic Surfactants) on Heterogeneous Surfaces
Abstract
The mechanisms of adsorption-abstraction of surfactants on heterogeneous surfaces can be described by taking into account: 1) the importance of lateral bonds that favour the formation of aggregates through a cooperative process on surfaces, 2) the intensity of normal adsorbate- adsorbent bonds that favour either the formation of two-dimensional aggregates in the monolayer range and at higher concentration the formation of a bilayer, if the interaction with the solid is strong or if the temperature is lower than the Krafft point, or the formation of micelles in the case of weak interaction with the solid surface (T > TK), 3) the importance of energetic surface hetero- geneity which controls the size of two-dimensional aggregates, and 4) the possible association of ionic surfactants with ions in solution that leads to bulk or surface precipitation (three-dimensional condensation on substrate). The importance of the selection of a reference phase and the specific methods to determine the nature of the adsorbed-abstracted phase are discussed.
J. M. Cases, F. Villieras
1.3. Electrochemistry in the Plant
Abstract
Electrochemical mechanisms governing the mineral-reagent interaction and inter- mineral interactions are reviewed. Two electrochemical factors of practical importance in flotation are the pulp potential and galvanic interactions. Examples of industrial importance are discussed. Two developments in sulphide flotation which are related to the electrochemistry of the system are collectorless flotation and nitrogen flotation. The practical importance of each in the processing of complex ores is described. Use of specific electrodes, measurement of pulp potential and its use to monitor and possibly control flotation are discussed.
S. R. Rao, G. Labonté, J. A. Finch
1.4. Flocculation of Fine Particles
Abstract
The basic principles of colloid stability, destabilisation and flocculation are reviewed, starting from the effects of simple salts. The role of adsorbed materials, especially polymers, on stability is considered in some detail and some practical implications are discussed. Factors influencing the rate of flocculation are outlined and the importance of particle size is emphasised.
John Gregory
1.5. Applied Mineralogy and Materials Balancing Procedures. Evaluations of Flotation Concentrators
Abstract
Quantitative mineralogical analysis combined with materials balancing of the mineral data provide a reliable method for evaluating the behaviour of a concentrator with respect to a specific ore. The quantitative mineralogical analysis involves determining size distributions of minerals in unbroken ore pieces to predict the grind for liberating the minerals and determining quantities, sizes, and degrees of liberations of the minerals in mill products from a concentrating unit. The materials balancing calculation determines recoveries of each type of mineral-bearing particle at each point in a flowsheet. Factors that affect recoveries by flotation of Zn, Cu, Pb, Ag, Au and Sn from volcanogenic base metal ores have been evaluated by this technique. Recoveries are discussed for sphalerite from the Brunswick No. 12 deposit in New Brunswick, Canada; for chalcopyrite, galena, silver and gold from several Canadian deposits; and for Sn from the Kidd Creek deposit in Ontario, Canada.
W. Petruk
1.6. Liberation by Size Reduction. Consequences and Improvements on Flotation Kinetics
Abstract
The first part of this lecture aims at emphasising the important role played by particle size on the general formulation of a separation process by means of its influence on the liberation status of a given ore. Liberation, seen as a static state of a particulate system, is described by means of a marginal probability density of grade, the computation of which compels us to define and use a grade distribution density conditional on size. Liberation is then considered as a dynamic state evolving along comminution time. Both cases of non-discriminating (transgranular) and discriminating (perigranular and transgranular preferential) comminution are referred. For the non- discriminating case, a limit probability argument is used to justify the introduction of the Euler Beta Law as a well suited tool for describing the liberation state of a comminuted ore, since it is able to predict the grade distribution of a given iso-size fraction. Considering this previous general model of liberation by size reduction as a good support, flotation kinetics is reviewed in order to provide evidence for the kinetic rate constants (seen as non-wettability parameters) as dependent on the grade distribution conditional on size. Simulation of traditional experiments, such as washability curves and release analysis, supported by the modelled liberation phenomenon and a good condensation of the kinetical parameters, is shown to be feasible. Finally, some numerical experiments of an elementary flotation kinetic model are performed in order to enhance the influence of size and degree of liberation on flowsheet performance.
M. R. Machado Leite
1.7. Elements of Physically-Based Modelling of the Flotation Process
Abstract
The general aim of physical modelling of flotation is to precalculate floatability of a component as a function of flotation time, on the basis of physical, physico-chemical and hydrodynamic parameters, e.g. interparticle and hydrodynamic forces. Drastic simplifications are necessary in modelling, in order one to be able to describe the overall process clearly.
H. J. Schulze

Chemical Technology Aspects

Frontmatter
2.1. Flotation Kinetics
Abstract
Flotation kinetics is briefly introduced and its history is reviewed. Main theoretical approaches are discussed, and the kinetic models are presented in detail. The application of flotation kinetics to modeling and simulation of the circuits is shortly surveyed, then some industrial results are used to show how the models fit to experimental results.
C. Ek
2.2. Mixing and Hydrodynamics in Flotation Cells
Abstract
The flotation process is a complex interaction between the physicochemical characte- ristics of the species involved and the hydrodynamic and operating conditions in flotation cells. Efficient cell design requires knowledge about the power to be provided and the time to be spent in the cell by each one of the phases. A review of new work in terms of mixing is presented, with particular attention to the effects of turbulence on flotation. The experimental and theoretical work on residence time ditributions in flotation cells is also presented.
P. Mavros
2.3. Case Studies of Flotation Control
Abstract
Significant progress has been made in the development of automatic control systems of flotation circuits since the first availability of on stream analysis data approximately 20 years ago. A wide range of approaches has been tested, from simple feedback control loops to advanced model based control strategies. Flotation control systems can be considered as either stabilising or optimising in nature.
Flotation control has proved to be a difficult task, principally because the process is subjected to disturbances which are not measurable in many cases, and because of inconsistent process response to disturbances. There has also been considerable confusion over the formation of realistic objectives for control systems.
An approach has emerged from the experience gained from many studies. It is crucially important to specify realistic control objectives at the outset. In almost every instance, control should commence with stabilising loops. Only after stable circuit operation has been achieved should the next goal of process optimisation be attempted. The task of achieving effective stabilising control can be quite challenging, and a range of techniques has been developed. The most recent of these recognizes the role and skill of the flotation operator via an expert systems approach.
The Julius Kruttschnitt Mineral Research Centre has been involved in the development of flotation control systems for 15 years. The paper will present accumulated experience of the Centre by outlining a selection of case studies which demonstrate different approaches to flotation control.
D. J. McKee
2.4. Mineral Surface Complexation in Flotation
Abstract
The equilibrium constants of surface chemical reactions are defined to describe mineral surface complexation. An experimental technique is presented involving potentiometric titrations of mineral suspensions supplemented by adsorption studies, solubility and zeta potential measurements. Experimental data are evaluated using advanced computer programs giving equilibrium constants of relevant surface reactions. The fundamentals of mineral surface complexation and their meaning in flotation are presented and discussed and used to interpret surface charge, as well as surface reactions with collectors, activators and depressants. Surface speciation and flotation principles are correlated for a sulphide (e.g. galena) and oxide mineral (e.g. quartz) system.
Z.-X. Sun, W. Forsling
2.5. Amide-Based Technologies in Flotation and Hydrometallurgy of Precious Metals
Abstract
A process for recovering gold and silver and making quartz suitable for the glass industry, comprising flotation, magnetic separation, leaching and sorption, is described. The sorbent is a native ionite - low calorific brown coal which needs no regeneration. A two-stage sorption is considered necessary for good gold recovery; the loaded sorbent is then subject to burning for final precious metals recovery.
St. Gaidarjiev, S. Spassova
2.6. Determination of Floatability Data Using the Emdee™ Microflot Method
Abstract
The discovery of the particle — bubble attachment/detachment equilibrium in a vigorously agitated closed mineral/reagent system offers new research opportunities for the flotation scientist. This mechanical/ thermodynamic equilibrium offers a potential link between thermodynamic principles and the performance of continuous flotation systems. The set of subsequent equilibria determined on the head sample by this method constitutes a mineral floatabi- lity spectrum for a given ore/reagent system. The results relate to flotation rate constants in a batch cell, so these data may be used for prediction of batch cell kinetics.
M. W. Chudacek
2.7. Froth Flotation Kinetics — Theory and Model Experiments
Abstract
The problem of froth kinetics is treated as a transport phenomenon. Two coupled equations of balance are formulated concerning the particles attached on the bubbles and the free particles in the pulp. Special attention is paid to the mode of interaction between particles and gas bubbles under dynamic conditions in a flotation cell. In contrast to the well known empirical first- order chemical reaction rate model, the solution in the present paper predicts similar but not exactly the same behaviour of the recovery rate. The adequacy of the theoretical assumptions is checked by means of laboratory flotation experiments with glass ballotini. The floatability of the particles is compared with their three-phase contact angles.
B. Radoev, L. Alexandrova
2.8. Electrolytic Flotation
Abstract
This is a rather unconventional separation process, owing its name to the bubbles generation method it uses, i.e. the electrolysis of an aqueous solution.
K. A. Matis

Mineral Processing

Frontmatter
3.1. Features and Flotation of Complex Cu-Pb-Zn Sulphides
Abstract
Problems arising during flotation of complex Cu-Pb-Zn sulphide ores are in general of geological origin. The features of these ores are reviewed, stressing that mineralogical studies extending to process mineralogy are prerequisite for a consistent flotation process. Some examples affecting flotation are given. Flotation of such ores often requires intensive testing to develop an economically viable circuit configuration. Particular attention is paid to the use of depressants, namely sulphur dioxide and sulphides. Some of the recent research results and industrial experience on the production of selective copper and zinc concentrates are briefly discussed. A case study of flotation of a complex Cu-Zn sulphide ore is outlined.
I. Bayraktar, U. A. Ipekoglu, R. Tolun
3.2. Interactions of Anionic Collectors in Flotation of Semi-Soluble Salt Minerals
Abstract
Our recent studies on the interaction of oleate with salt-type mineral surfaces have been summarised and discussed in the light of the published literature. The mechanism of oleate adsorption on these minerals was evaluated based on adsorption, zeta potential and infrared studies as well as theoretical thermodynamic calculations. In contrast to earlier knowledge, a quantitative evaluation of oleate adsorption in systems forming a monolayer coverage as in the case of calcite and a bilayer formation in the cases of fluorite, apatite, scheelite and baryte, preceding the precipitation of metal soap is presented. The monolayer coverage is shown to correspond to a condensed state of oleate with a molecular coverage area of 33 Å2 (liquid crystal state). Depending on the surface potential and its magnitude at basic pH values, oleate is either chemisorbed on the surface calcium or monocoordinated through counter sodium and calcium ions for the monolayer filling. The results have been discussed in terms of the existing adsorption models.
K. Hanumantha Rao, K. S. E. Forssberg
3.3. Flotation of Salt-Type Minerals
Abstract
Salt-type minerals flotation is discussed, based mainly on experiments on magnesite, dolomite and calcite. Among the parameters affecting flotation, the following are examined : crystal structure, solubility of minerals, surface charge, collectors, organic and inorganic modifiers, adsorption, contact angle and floatability. The selective separation by flotation of salt-type minerals from each other and from silicates is also investigated.
G. P. Gallios, K. A. Matis
3.4. Vibroacoustic Improvements of Froth Flotation
Abstract
The vibroacoustic technique is used in various industrial processes in the chemical industry, building, robotics, agriculture etc. Some important economic advantages of this method were proved, e.g. the high relative productivity, the high quality of products, lower energy and water consumption, convenience for automation, etc. In mineral processing, the vibroacoustic technique is mainly used in discharging hoppers, feeding, transportation, sieving, grinding, ore- washing and table concentration. Vibroacoustic crushers, flat surface concentrators, cementators, extractors, dryers etc. have already been adopted and introduced in practice.
In separation processes, however, vibroacoustic techniques have been insufficiently applied. A number of investigations have shown the positive effect of vibroacoustics on flotation. The aim of this paper is to acquaint the mineral processing specialists with results (obtained by the authors) in studying various vibroacoustic effects on the separate stages of the flotation process, i.e. preparation of the pulp and reagents, formation and behaviour of the bubbles, secondary concentration in the froth layer, desorption of the reagents, joint accomplishment of grinding and flotation. A description is also given of two designs of vibroacoustic flotation machines. The technological and economic results obtained justify the increasing interest on the part of researchers and technologists in the vibroacoustic method as a means of improving the froth flotation technology.
St. Stoev, L. Kuzev, M. Metodiev, Sht. Djendova
3.5. The Institute of Geology and Mineral Exploration (IGME) of Greece and its Research Activities on Flotation
Abstract
The Institute rof Geology and Mineral Exploration is a research institute in the geological, hydrogeological, geotechnical and mining field aiming at higher rates of development of Greece in these fields. The task of the Mineral Processing Department is the beneficiation study of Greek minerals and ores. Its activity covers a wide range of ore beneficiation, either in laboratory or in pilot plant scale equipment; results are recorded in mostly non-confidential publications. Scientific collaboration with other countries is encouraged.
D. Malliaris
3.6. The Influence of Multivalent Cations on the Floatability of Scheelite, Fluorite and Calcite
Abstract
The physicochemical properties of the mineral interfaces of CaWO4, CaF2 and CaCO3 in the presence of multivalent cations (Ca2+, Mg2+, Al3∋) during the flotation process were investigated. Flotation experiments, zeta potential and ESCA measurements were made for the characterisation of the mineral surfaces and the utilisation of different kinds of zeolites in the flotation systems was examined.
S. Raatz
3.7. Non-Cyanide Technology for the Flotation of Lead-Zinc Ores
Abstract
One of the most important initial studies in mineral processing is the measure of floatability in order to determine the appropriate chemical reagents and also to investigate the surface properties of the particles.
V. Panayotov

Water and Wastewater Treatment

Frontmatter
4.1. Flotation in Water Treatment
Abstract
Dissolved-air flotation is a very effective solid-liquid separation process used in water treatment, as an alternative to sedimentation, to lower the solids concentrations before granular filtration. This enables filters to be operated more effectively and cost efficiently to produce a filtered water quality suitable, after disinfection, for potable supply. Dissolved-air flotation has been specifically developed for the treatment of algal laden and coloured waters. The flocs produced by the treatment of these waters have a low settling velocity, particularly when the water temperature is low and even when polyelectrolytes are added. Treating these waters, flotation requires smaller tanks and produces better treated water quality, compared to sedimentation. Dissolved-air flotation has become accepted as an alternative to sedimentation, in particular in the Scandinavian countries and the United Kingdom, with more than 50 plants in operation or under construction. The largest dissolved-air flotation plant currently being constructed is the 315 Ml/day Frankley water treatment works in the UK.
Th. F. Zabel
4.2. Mechanism of Selective Ion Flotation
Abstract
It has been determined that ion-water and cation-surface active anion interactions govern the ion flotation selectivity, when a sublate was not formed in the bulk solution. The flotation selectivity orders of anions were correlated with the experimentally-determined viscosity coefficients, whereas the flotation selectivity orders of cations were correlated with their ionic potential values. It has been found that, if sublate precipitation takes place in the bulk solution, the surface charge of sublate was the key factor influencing the floatability of an ion. Basic properties of sublates, e.g. the solubility and electrokinetic potential in aqueous solution have been determined. Ion flotation kinetics, using cobalt(II) and cobalt(III) ions as an example, is also considered in this study.
Wl. Walkowiak
4.3. Flotation Techniques in Waste Water Treatment
Abstract
In today’s world of environmental strain, waste water treatment is becoming a more or less conventional application of flotation as, for instance, in the oil, food or chemical industries, sewage treatment, etc. In this paper, different flotation methods (ion flotation, precipitate flotation, adsorbing colloid flotation), and techniques (dispersed-air, electrolytic and dissolved-air flotation) are rewiewed and several applications of these for waste water treatment are presented, noting the need for further chemical engineering development and knowledge of this process. Selected bench- scale experimental results are also given, specifically for the removal of dyes, phosphates and toxic metals, including chromium, silver and copper, the latter on pyrite fines. The processing of dilute aqueous metal solutions for precious metals recovery is stressed, possibly as an alternative to hydrometallurgy.
A. I. Zouboulis, K. A. Matis, G. A. Stalidis
4.4. Flotation of Pigments and Inks from Waste Paper
Abstract
Waste paper processing gains more and more importance for environmental and technological reasons. Herewith in connection, the deinking flotation plays an important role. In this paper the basic terms of the deinking process are presented.
B. Dobias, W. Klar, K. Schwinger
4.5. A Case Study of Flotation Applied to an Edible Oil Factory Wastewater
Abstract
Flotation is applied to many edible oil wastewater treatment plants in Turkey. In this study, the wastewaters of an edible oil industry near Izmir have been treated by flotation in laboratory conditions and various kinds of polymers have been applied in order to increase the flotation efficiency.
A. Türkman, F. Sengül, N. Özel
4.6. The Need for Advanced Treatment of Storm-Water Run-Off from Separate Sewer Systems
Abstract
A wide spectrum of anthropogenic pollutants exists in surface run-off resulting from precipitation. These are mainly organic micropollutants and heavy metals, which are transported in association with finer suspended solids. Conventional treatment methods for storm-water run-off using sedimentation alone are not sufficient for reducing the input of particulate materials with adsorbed contaminants to natural waters. Chemical precipitation/coagulation is effective in produ- cing separable aggregates and phase separation using flotation or cyclone and vortex separators can then be applied to remove them from storm-water.
R. Pfeifer, H. H. Hahn
Backmatter
Metadaten
Titel
Innovations in Flotation Technology
herausgegeben von
P. Mavros
K. A. Matis
Copyright-Jahr
1992
Verlag
Springer Netherlands
Electronic ISBN
978-94-011-2658-8
Print ISBN
978-94-010-5175-0
DOI
https://doi.org/10.1007/978-94-011-2658-8