Flotation in mineral processing

Shergold, H.L. Flotation in Mineral Processing in The Scientific Basis of Flotation, Ives,... 

The structure electrical double layer at the silica-aqueous electrolyte interface was one of the earlier examined of the oxide systems. At the beginning the investigations were performed with application of electrokinetic methods next, with potentiometric titrations. The properties of this system were very important for flotation in mineral processing. Measurements proved that pHpZC and pHiep are equal to 3, but presence of some alkaline or acidic contaminants may change the position of these points on pH scale. Few examples, concerning edl parameters are shown in Table 3. Presented data concern a group of systems of different composition of the liquid phase and solid of a different origin. The latest measurements of this system takes into account the kinetics of the silica dissolution [152], and at zeta measurements, also the porosity of dispersed solid [155]. 

Shergold, H. L. 1984. Flotation in mineral processing. In The Scientific Basis of Flotation, Ed, K. J. Ives. 

Flotation. Flotation is a gravity separation process which exploits differences in the surface properties of particles. Gas bubbles are generated in a liquid and become attached to solid particles or immiscible liquid droplets, causing the particles or droplets to rise to the surface. This is used to separate mixtures of solid-solid particles and liquid-liquid mixtures of finely divided immiscible droplets. It is an important technique in mineral processing, where it is used to separate different types of ore. 

Flotation is an important technique in mineral processing, where it is used to separate different types of ores. When used to separate solid-solid mixtures, the material is ground to a particle size small enough to liberate particles of the chemical species to be recovered. The mixture of solid particles is then dispersed in the flotation medium, which is usually water. The mixture is then fed to a flotation cell, as illustrated in Figure 8.12a. Here, gas is also fed to the cell where gas bubbles become attached to the solid particles, thereby allowing them to float to the surface of the liquid. The solid particles are collected from the surface by an overflow weir or mechanical scraper. The separation of the solid particles depends on the different species having different surface properties such that one species is preferentially attached to the bubbles. A number of chemicals can be added to the flotation medium to meet the various requirements of the flotation process ... 

Persson, I., Persson, P., Valli, M., Fozo, S., Malmensten, B., 1991. Reaction on sulphide mineral surfaces in connection with xanthate flotation studied by diffuse reflectance FTIR spectroscopy, atomic absorption spectrophotometry and calorimetry. In K. S. E. Forssberg (ed.). Flotation of Sulphide Mineral. Inter. J. Miner. Process, 33 67 - 81 Peters, E., 1977. The electrochemistry of sulphide minerals. In J. O M. Bockris, D. A. J. Rand, B. J. Weich (eds.). Trends in Electrochemistry. New York Plenum Press, 267 - 290 Peters, E., 1986. Leaching of sulphides. In P. Sortunasundaran (ed.). Advances in Mineral Processing. Proc. Sym. Honoring N. Arbiter on His 75th Birthday, SME, Inc. Colorado, 445-462... 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

In mineral processing, any process that results in a product having an improved desired mineral content. Example froth flotation. 

In the preliminary treatment of an ore, the desired mineral is separated from waste materials—usually clay and silicate minerals—which are collectively called the gangue. One very useful method for carrying out such a separation is caHed flotation. In this process the ore is finely ground and added to water containing oil and detergent. The liquid mixture is then beaten or blown to form a froth. The oil preferentially wets the... 

Guartec. QHenkd] Guar-bas prods. flotation reagent, dqjressant, floccu-lant used in mineral processing. 

The existence of optimum concentrations for separation- and flotation-aid surfactants is qnite common in mineral processing operations. In oil sand processing, reasons for reductions in process efficiency at higher than the optimum concentrations may be due to the formation of different adsorption layer orientations and/or multiple adsorption layers at interfaces. Either or both of these could explain the observed reductions in surface electric charge (Zeta potential) at the bitumen/aqueous and gas/ aqueous interfaces (see Figure 14). 

Gravity sedimentation equipment, hydrocyclones, sedimenting centrifuges or flotation cells have also been extensively used in mineral processing for separation of minerals according to density or affinity to water. In such separations, the efficiency is expressed by the Tromp curve which, similar to the grade efficiency curve, shows probability of separation as a function of material density or mineral composition. The steepness of the curve is a measure of the sharpness of the separation. 

Froth flotation is a complex three phase physico-chemical process which is used in mineral processing industry to separate selectively fine valuable minerals from gangue. The importance of the mineral froth flotation process to the economy of the whole industrial world is important. As costs has increased in mining industry and ore grades and metal prices decreased, role of mineral flotation has become even more important. The flotation process depends among many other factors on control of the pulp aeration, agitation intensity, residence time of bubbles in pulp, pulp density, bubble and particle size and interaction and pulp chemistry. 

Ab initio methods solve the molecular Schrodinger equation associated with the molecular Hamiltonian based on different quantum-chemical methodologies that are derived directly from theoretical principles without inclusion of any empirical or semiempirical parameters in the equations. Though rigorously defined on first principles (quantum theory), the solutions from ab initio methods are obtained within an error margin that is qualitatively known beforehand thus all the solutions are approximate to some extent. Due to the expensive computational cost, ab initio methods are rarely used directly to study the physicochemical properties of flotation systems in mineral processing, but their application in developing force fields for molecular mechanics (MM) and MD simulation has been extensively documented. (Cacelli et al. 2004 Cho et al. 2002 Kamiya et al. 

Solids separation from liquid is a common requirement in many industries. Typically used for the treatment of industrial and mimidpal wastes, and in mineral processing operations where water is used as the vehicle to grind and separate minerals via differential dissolution, precipitation, flotation or density. 

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