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A. López Valdivieso A.A. Sánchez López C. Ojeda Escamilla M.C. Fuerstenau 《International Journal of Mineral Processing》2006
The role of pH and pulp redox potential (EH) to control the flotation and depression of arsenopyrite has been investigated through studies on microflotation of arsenopyrite crystals and batch flotation of an arsenopyritic ore using isopropyl xanthate as collector. The transition between flotation and depression of arsenopyrite is established by the reversible potential of the xanthate/dixanthogen couple. Adsorption of arsenate ions on ferric hydroxide has been studied through electrokinetics to delineate mechanisms involved in the depression of arsenopyrite using oxidants. Chemical binding between arsenate species and ferric hydroxide sites on arsenopyrite is suggested as the mechanism responsible for depression of arsenopyrite. EH conditions are given for the flotation and depression of arsenopyite at various pH values for the arsenopyritic ore. 相似文献
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A robust and reliable sensor to measure gas (air) superficial velocity (Jg) continuously in flotation systems is introduced. It is based on the sampling of bubbles by buoyancy with the accumulating air allowed to exit through an orifice. At steady state, pressure drop is measured and related to the Jg by prior calibration. The continuous device is readily automated and extended to a multi-unit set-up. The sensor and data collections are described. The governing gas flow equation and models of the dynamic response to air flow rate set point change and fluctuations in froth depth are derived. Model predictions are confirmed against plant data. By taking a moving average, the Jg remains valid in the face of typical plant disturbances. 相似文献
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The uppermost surface of the ocean forms a peculiarly important ecosystem, the sea surface microlayer (SML). Comprising the top 1–1000 μm of the ocean surface, the SML concentrates many chemical substances, particularly those that are surface active. Important economically as a nursery for fish eggs and larvae, the SML unfortunately is also especially vulnerable to pollution. Contaminants that settle out from the air, have low solubility, or attach to floatable matter tend to accumulate in the SML.Bubbles contribute prominently to the dynamics of air–sea exchanges, playing an important role in geochemical cycling of material in the upper ocean and SML. In addition to the movement of bubbles, the development of a bubble cloud interrelates with the single particle dynamics of all other bubbles and particles. In the early sixties, several in situ oceanographic techniques revealed an “unbelievably immense” number of coastal bubbles of radius 15–300 μm. The spatial and temporal variation of bubble numbers were studied; acoustical oceanographers now use bubbles as tracers to determine ocean processes near the ocean surface. Sea state and rain noises have both been definitively ascribed to the radiation from huge numbers of infant micro bubbles [The Acoustic Bubble. Academic Press, San Diego].Our research programme aims at constructing a hydrodynamic model for particle transport processes occurring at the microscale, in multi-phase flotation suspensions. Current research addresses bubble and floc microhydrodynamics as building blocks for a microscale transport model. This paper reviews sea surface transport processes in the microlayer and the lower atmosphere, and identifies those amenable to microhydrodynamic modelling and simulation. It presents preliminary simulation results including the multi-body hydrodynamic mobility functions for the modelling of “dynamic bubble filters” and floc suspensions. Hydrodynamic interactions versus spatial anisotropy and size of particle clouds are investigated. 相似文献
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A.-Z.M. Abouzeid A.T. Negm D.A. Elgillani 《International Journal of Mineral Processing》2009,90(1-4):81-89
Sedimentary phosphates contain-besides the phosphate minerals-, various associated gangue minerals such as: clays, silica, calcareous minerals (mainly calcite and dolomite), carbonaceous matter, iron oxides and/or pyrite. The common practiced flow-sheets for concentrating these types of phosphate ores consist of a combination of various mineral processing units such as: crushing and screening, attrition, washing, magnetic separation, and/or flotation. However, none of these combinations was successfully efficient to upgrade the calcareous ores because of the close similarity of the physical properties (density, particle size, particle shape, etc.) as well as the surface physico-chemical properties of the carbonate and phosphate minerals. For the last five decades extensive efforts have been spent to adopt flotation for separating carbonates from phosphate ores. These efforts include thermodynamic analysis, modification of the technique, controlling the pulp environment, and finding new reagents that can specifically differentiate between carbonates and phosphates.This paper reviews some of the published work on the separation of carbonates from phosphate ores by flotation and presents the flotation results of phosphate ore samples different in their physical properties and mineralogical composition. The results obtained reflect the effect of ore nature on the flotation performance and the reagents consumption. 相似文献
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Investigation on foaming properties of some organics for oily bubble bitumen flotation 总被引：1，自引：0，他引：1
Studies have shown that using organic coated bubbles (“oily” bubbles) could increase bitumen recovery rate in flotation. One way to coat bubbles is that used in the air-assisted solvent extraction process where solvent foam is formed and injected through a capillary to release solvent coated bubbles in a controlled manner into the aqueous system. To investigate adapting this approach, the foaming properties of some organics (Hexane, Heptane, Hexadecane, Petroleum Ether, Toluene, Benzene and Kerosene and their binary mixtures) of potential interest in oily bubble bitumen flotation were investigated. Silicone oil was found to be a good foaming agent in some cases. Bubble stability and film thickness experiments were carried out to help select candidate organics. Surface tension and dynamic viscosity measurements were conducted to examine the mechanism of foaming. Attachment studies showed that droplets of the selected organics readily attached to a bitumen surface compared to air bubbles. From a combination of criteria, 25:75 Hexadecane/Heptane appears to be a promising candidate. 相似文献
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Arsenic is one of the most dangerous inorganic pollutants and thus a penalty element in many base metal concentrates. Arsenic removal in sulphide flotation has been studied extensively with various approaches, including pre-oxidation of flotation pulp, Eh control during flotation and the use of selective depressants/collectors. Pre-oxidation of flotation pulp using oxidizing agents or aeration conditioning represents a simple approach in arsenic removal and was found effective in many cases. Selective flotation of arsenic minerals through Eh control has made significant advances in recent years with promising results achieved. In addition, various depressants and collectors have also been studied in arsenic removal. In this communication, the various approaches used in selective flotation of arsenic minerals are reviewed with emphasis on the development in recent years. 相似文献
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Effects of surface forces and film elasticity on foam stability 总被引：1，自引：0，他引：1
The thin film pressure balance (TFPB) technique was used to determine the surface forces in foam films stabilized with flotation frothers such as n-pentanol, n-octanol, methyl isobutyl carbinol (MIBC), and polypropylene glycol (PPG). The results were compared with the foam stabilities measured experimentally and the film elasticities calculated using a model developed by Wang and Yoon [Wang, L., Yoon, R.-H., 2006a. Role of hydrophobic force in the thinning of foam films containing a nonionic surfactant. Colloids Surfaces A: Physicochem. Eng. Aspects, 282–283, 84–91.]. It was found that foam stabilities are controlled by both film elasticity and disjoining pressure, the relative contributions from each changing with frother type and concentration. At relatively low concentrations, frother dampens the hydrophobic force, an attractive component of the disjoining pressure, that destabilizes foams. At higher concentrations, elasticity plays a more important role in stabilizing foams. 相似文献
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Donald Mkhonto Phuti E. Ngoepe Timothy G. Cooper Nora H. de Leeuw 《Physics and Chemistry of Minerals》2006,33(5):314-331
Computer modelling techniques were employed to investigate the adsorption of a selection of organic surfactant molecules to a range of fluorapatite surfaces, and new interatomic potential models for the apatite/adsorbate interactions are presented. The adsorbates coordinate mainly to the surfaces through interaction between their oxygen (or nitrogen) atoms to surface calcium ions, followed by hydrogen-bonded interactions to surface oxygen ions and, to a much lesser extent, surface fluorides. Bridging between two surface calcium ions is the preferred mode of adsorption, when the geometry of the adsorbates allows it, and multiple interactions between surfaces and adsorbate molecules lead to the largest adsorption energies. All adsorbates containing carbonyl and hydroxy groups interact strongly with the surfaces, releasing energies between approximately 100 and 215 kJ mol−1, but methylamine containing only the –NH2 functional group adsorbs to the surfaces to a much lesser extent (25–95 kJ mol−1). Both hydroxy methanamide and hydroxy ethanal prefer to adsorb to some surfaces in an eclipsed conformation, which is a requisite for these functional groups. Sorption of the organic material by replacement of pre-adsorbed water at different surface features is calculated to be mainly exothermic for methanoic acid, hydroxy methanamide and hydroxy ethanal molecules, whereas methyl amine would not replace pre-adsorbed water at the fluorapatite surfaces. The efficacy of the surfactant molecules is calculated to be hydroxy aldehydes > alkyl hydroxamates > carboxylic acids ≫ alkyl amines. The results from this study suggest that computer simulations may provide a route to the identification or even design of particular organic surfactants for use in mineral separation by flotation. 相似文献