Flotation Chemistry

Minerals belonging to the category of insoluble oxide and silicate minerals are many in number. Insoluble oxide minerals include those superficially oxidized and those of oxide type. The former category comprises mainly superficially oxidized sulfide minerals, including metals such as aluminum, tin, manganese, and iron which are won from their oxidic sources. As far as silicate minerals are concerned, there can be a ready reference to several metals such as beryllium, lithium, titanium, zirconium, and niobium which are known for their occurrence as (or are associated with) complex silicates in relatively low-grade deposits. 

Those minerals whose solubilities are greater than those of most oxides and silicates, but lower than those of soluble salt minerals, are grouped as semisoluble salt minerals (also called salt-type minerals). The list comprising this particular minerals group is calcite, dolomite, magnesite, barite, gypsum, scheelite, carbonate, phosphate, sulfate and some others. These minerals are characterized mainly by their tonic bonding and as has already been pointed out, by their moderate solubility. 

Separation of these minerals from oxides and silicates can be readily accomplished as the surface chemical and physical properties of these minerals are very similar. On account of this fact, separation of the metals themselves has proved to be extremely difficult. 

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Flossofen, m. flowing furnace. Flotationschemie, /, flotation chemistry, flotationsfahig, a. floatable, Flotationsverfahren, n. flotation process. Flotator, m. flotation machine, flotierbar, a. floatable, flotieren, v.t. float. 

Kirchherg, H., and Wottgen, L., The Effect of Phosphorus and Antimony Surfactants on Cassiterite Flotation, Chemistry, Physics and Application of Surface Active Substances, London, pp. 693-704, 1976. 

Kantar, C. (2002) Solution and flotation chemistry of enargite. Colloids and Surfaces A Physicochemical and Engineering Aspects, 210(1), 23-31. 

Fuerstenau, D. W. (1995) Where we are in flotation chemistry after 70 years of research, Proceedings of the International Mineral Processing Congress, 19th, San Francisco, 1995, 3,3-17. 

In many flotation systems, the electrical nature of the mineral/water interface controls the adsorption of collectors. The flotation behavior of insoluble oxide minerals, for example, is best understood in terms of electrical double-layer phenomena. A very useful tool for the study of these phenomena in mineral/water systems is the measurement of electrokinetic potential, which results from the interrelation between mechanical fluid dynamic forces and interfacial potentials. Two methods most commonly used in flotation chemistry research for evaluation of the electrokinetic potential are electrophoresis and streaming potential. 

Understanding the adsorption of long-chain alkyl amines and their surface structure is significant for improved nonsulfide flotation technology and the development of new flotation chemistry for the flotation of nonsulfide minerals. In the middle of the twentieth century, Gaudin and Fuerstenau first studied the use of long-chain alkyl amines for the flotation of oxide minerals, particularly the flotation of quartz with primary dodecylamine (DDA) (Gaudin and Fuerstenau 1955). Their studies showed that the collector adsorption density and zeta potential at the solid-water interface are... 

A very important but rather complex application of surface chemistry is to the separation of various types of solid particles from each other by what is known as flotation. The general method is of enormous importance to the mining industry it permits large-scale and economic processing of crushed ores whereby the desired mineral is separated from the gangue or non-mineral-containing material. Originally applied only to certain sulfide and oxide ores. 

Flotation reagents are used in the froth flotation process to (/) enhance hydrophobicity, (2) control selectivity, (J) enhance recovery and grade, and (4) affect the velocity (kinetics) of the separation process. These chemicals are classified based on utili2ation collector, frother, auxiUary reagent, or based on reagent chemistry polar, nonpolar, and anionic, cationic, nonionic, and amphoteric. The active groups of the reagent molecules are typically carboxylates, xanthates, sulfates or sulfonates, and ammonium salts. 

J. Leja, Surface Chemistry of Froth Flotation, Plenum Press, New York, 1982. 

Flotation. Flotation (qv) is used alone or in combination with washing and cleaning to deink office paper and mixtures of old newsprint and old magazines (26). An effective flotation process must fulfill four functions. (/) The process must efficiently entrain air. Air bubble diameter is about 1000 p.m. Typically air bubbles occupy 25—60% of the flotation cell volume. Increa sing the airRquid ratio in the flotation cell is said to improve ink removal efficiency (27). (2) Ink must attach to air bubbles. This is primarily a function of surfactant chemistry. Air bubbles must have sufficient residence time in the cell for ink attachment to occur. (3) There must be minimal trapping of cellulose fibers in the froth layer. This depends on both cell design and surfactant chemistry. (4) The froth layer must be separated from the pulp slurry before too many air bubbles coUapse and return ink particles to the pulp slurry. 

Ladle metallurgy, the treatment of Hquid steel in the ladle, is a field in which several new processes, or new combinations of old processes, continue to be developed (19,20). The objectives often include one or more of the following on a given heat more efficient methods for alloy additions and control of final chemistry improved temperature and composition homogenisation inclusion flotation desulfurization and dephosphorization sulfide and oxide shape control and vacuum degassing, especially for hydrogen and carbon monoxide to make interstitial-free (IF) steels. Electric arcs are normally used to raise the temperature of the Hquid metal (ladle arc furnace). 

G. H. Harris, Reagents in MineralTechnology, Surfactant Science Series, Vol. 27, Marcel Dekker, Inc., New York, 1988, pp. 371—383. f. Leja, Suface Chemistry of Froth Flotation, Plenum Press, New York, 1982. 

Flotation is certainly the major separation method based on the surface chemistry of mineral particles. It is, however, not the only method. Selective flocculation and agglomeration may be mentioned as other methods used commercially to a limited extent. The former is for hematite, while the latter is for coal and finely divided metallic oxide minerals. Both processes use the same principles as described for flotation to obtain selectivity. In selective flocculation, polymeric flocculants are used. The flocculants selectively adsorb on the hematite, and the hematite floes form and settle readily. Thereby separation from the sili-... 

M. C. Fuerstenau, J. D. Miller and M. C. Kuhn, Chemistry of Flotation, Sodety of Mineral Engineers.,... 

The first system, shown in Figure 6.6, is identical to the conventional reduction-precipitation in chemistry (i.e., neutralization, chromium reduction, pH adjustment, metal hydroxide precipitation, and so on). However, a flotation-filtration clarifier (Tank T101SF, as shown in Figure 6.6) is used. The unit consists of rapid mixing, flocculation, high-rate DAF, and sand filtration.1557... 

Several reviews on ore processing by flotation are available.17-21 In addition to providing details of the chemistry of collectors they describe the use of activators and depressants. The former usually convert the surfaces of an ore particle which does not bind strongly to conventional collectors to one that does. The addition of Cu2+ ions to enhance the flotability of minerals such as sphalerite, a zinc sulfide, has been exploited for some time.4 Formation of a surface layer of CuS has been assumed to account for this, but the mechanisms and selectivities of such processes continue to be investigated.18,22,23... 

Gonzales, G., The Recovery of Chrysocolla with Different Long Chain Surface-active Agents as Flotation Collectors, Journal of Applied Chemistry Biotechnology, Vol. 16, No. 28, pp. 31-38, 1978. 

The chemistry of cassiterite flotation has been a subject of considerable research for many years. The findings that sulphosuccinamates, phosphonic acid and arsonic acid were selective collectors for cassiterite flotation lead to the introduction of flotation as a complementary recovery process to gravity concentration at most primary tin mill concentrators in the early 1970s. In spite of continued research, subsequent progress in development has been rather limited. Cassiterite flotation still remains a secondary tin recovery process in most plants, for beneficiation of cassiterite below 40 pm size. 

Farah, M.Y., and Fayed, L.A., Oxalate Activation in the Flotation of Monazite by Heavy Sulphonate Collector, Egypt Journal of Chemistry, Vol. 1, p. 2363, 1958. 

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