Froth flotation reagents

Dry ice Acetic acid Ethyl Butyl acetates Cellulose paint thinners Animal feed supplements Froth flotation reagents... 

Chem. Descrip. Blend of low m.w. hydroxy-terminated low m.w. alkyl ethers Uses Froth flotation reagent... 

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. 

Table 6. Organic Auxiliary Reagents Used in Froth Flotation Technology...

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 reagents are selected to produce a stable froth and adjust the affinity of target minerals to collect in the froth. Other reagents depress the collection of minerals in the froth. The froth containing the copper minerals overflows into collection launders. 

Flotation Reagents. Three types of chemical reagents are used during the froth flotation process collectors, frothers, and modifiers. 

In the froth flotation cell used for coal washing, illustrated in Figure 1.48, the suspension contains about 10 per cent of solids, together with the necessary reagents. The liquid flows along the cell bank and passes over a weir, and directly enters the unit via a feed pipe and feed hood. Liquor is discharged radially from the impeller, through the diffuser, and... 

Froth flotation has proven to be an efficient method of removing titaniferous impurities (mainly iron-rich anatase) from kaolin clays. Fatty acid reagent, primarily tall oil, is used extensively in the reverse flotation of these impurities. This flotation collector typically requires divalent cations (usually Ca +) to activate the coloured impurities and enhance collector adsorption. This is not very selective since the tall oil can also absorb on the kaolinite particles. Alkyl hydroxamate collectors are relatively new in the kaolin industry but provide significant advantages. Hydroxamates do not require activators, substantially increase the removal of colored impurities and are very selective. 

Finely divided solids or immiscible liquids can be made to adhere to gas bubbles and then can be removed from the main liquid. Affinity of a solid for an air bubble can be enhanced with surfactants which adhere to the surface of the solid and make it nonwetting. The main application of froth flotation is to the separation of valuable minerals from gangue. Ores of Cu, Zn, Mo, Pb, and Ni are among those commercially preconcentrated in this way. Reagent requirements of each ore are unique and are established by test. A... 

Zinc and lead usually occur together in nature as sulfides. Earlier separation processes involved the fine grinding of the combined sulfides and then treating the particles with chemical reagents to cause one sulfide to be preferentially wetted and rhns the two sulfides separated by the froth flotation process. In a first stage, the lead sulfide is floated while the zinc sulfide sinks to the bottom of the tank. In the second stage, the process is reversed and the zinc sulfide is floated. Gangue and other nonmetals collect at the bottom of the tank. The separated sulfides are dewatered to a 6-7% moisture content and are referred to as the zinc concentrate and the lead concentrate. 

Collector reagent used in froth flotation to promote contact and adhesion between particles and air bubbles. 

For flotation to be most effective, reagents such as oil (collector) and surfactant (frother) must be added to the aqueous coal slurry. The collector adsorbs on the coal surface and makes it more hydrophobic, while the surfactant facilitates production of a stable froth. According to Leonard (26), the optimum coal sizes for froth flotation are between 50 and 140 mesh (0.3 and 0.106 mm). While conventional froth flotation will successfully remove minerals from coal, it has limited effect on the pyrite content, as pyrite tends to float almost as well as coal. Because of this, researchers have been looking for better ways to remove pyrite from coal. In addition, as previously mentioned, it is necessary to grind coal to very fine sizes in order to sufficiently liberate the mineral matter and pyritic sulfur. But, at these very fine sizes,... 

A small amount of ammonia is used as a modifying reagent in the froth flotation of phosphate ores. 

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