Mineral froth-flotation

The initial steps are similar to any other mineral extraction process. This involves crushing mineral, froth flotation, gravity concentration and other steps to obtain platinum metal concentrates that may contain about 30 to 40 wt% of platinum group metals. The concentrate is treated with aqua regia to separate soluble metals, gold, platinum, and palladium from other noble metals such as ruthenium, rhodium, iridium, osmium, and silver that remain in... 

The first application which comes into mind when thinking about liquid foams is in cleaning processes, such a shampoo or shaving foams. More important, however, are liquid foams in mineral froth flotation and, a closely related process, the de-inking of recycled paper. Other uses include fire fighting. In food we often find foams such as whipped cream or egg whites. 

By far, the largest technological application of liquid foams is in mineral froth flotation, and this process uses a substantial fraction of the world production of amphiphiles. Froth flotation is also used in other separation processes such as the deinking of recycled paper. Other uses of liquid foams include fire fighting, cleaning processes, drinks such as champagne or beer froth, foods such as whipped cream or egg white, and preparation of solid foams after solidification of the liquid continuous phase. 

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. 

Fig. XIII-4. Schematic diagram of a froth flotation cell. Note the mineralized bubble shown in the inset. [Reprinted with permission from P. Somasumdaran, Interfacial ChemisUy of Particulate Flotation. AIChE Symp. Sen, 71(150), 2 (1975) (Ref. 58). Reproduced by permission of the American Institute of Chemical Engineers.]...

Flotation or froth flotation is a physicochemical property-based separation process. It is widely utilised in the area of mineral processing also known as ore dressing and mineral beneftciation for mineral concentration. In addition to the mining and metallurgical industries, flotation also finds appHcations in sewage treatment, water purification, bitumen recovery from tar sands, and coal desulfurization. Nearly one biUion tons of ore are treated by this process aimuaHy in the world. Phosphate rock, precious metals, lead, zinc, copper, molybdenum, and tin-containing ores as well as coal are treated routinely by this process some flotation plants treat 200,000 tons of ore per day (see Mineral recovery and processing). Various aspects of flotation theory and practice have been treated in books and reviews (1 9). 

Froth flotation (qv) is a significant use of foam for physical separations. It is used to separate the more precious minerals from the waste rock extracted from mines. This method reHes on the different wetting properties typical for the different extracts. Usually, the waste rock is preferentially wet by water, whereas the more valuable minerals are typically hydrophobic. Thus the mixture of the two powders are immersed in water containing foam promoters. Also added are modifiers which help ensure that the surface of the waste rock is hydrophilic. Upon formation of a foam by bubbling air and by agitation, the waste rock remains in the water while the minerals go to the surface of the bubbles, and are entrapped in the foam. The foam rises, bringing... 

A U.S. Bureau of Mines survey covering 202 froth flotation plants in the United States showed that 198 million tons of material were treated by flotation in 1960 to recover 20 million tons of concentrates which contained approximately 1 billion in recoverable products. Most of the worlds copper, lead, zinc, molybdenum, and nickel are produced from ores that are concentrated first by flotation. In addition, flotation is commonly used for the recoveiy of fine coal and for the concentration of a wide range of mineral commodities including fluorspar, barite, glass sand, iron oxide, pyrite, manganese ore, clay, feldspar, mica, sponumene, bastnaesite, calcite, garnet, kyanite, and talc. 

Copper, Cu, is unreactive enough for some to be found as the metal, but most is produced from its sulfides, particularly the ore cbalcopyrite, CuFeS2 (Fig. 16.10). The crushed and ground ore is separated from excess rock by froth flotation, a process that depends on the ability of sulfide ores to be wetted by oils but not by water. In this process, the powdered ore is combined with oil, water, and detergents (Fig. 16.1 l). Then air is blown through the mixture the oil-coated sulfide mineral floats to the surface with the froth, and the unwanted copper-poor residue, which is called gangue, sinks to the bottom. 

Mercury, Hg, occurs mainly as HgS in the mineral cinnabar (see Fig. 15.11), from which it is separated by froth flotation and then roasting in air ... 

Bubbles with some of them attached with hydrophobic mineral particles shown in the rising mode. Hydrophilic mineral particles with minority presence of hydrophobic mineral particles (those lost chance for contact with bubbles) and bubbles attached with hydrophobic mineral particles (those got mechanically driven along with hydrophilic particles) shown in the descending mode. (B) Froth flotation air bubbles carry nonwetted particles upwards, while wetted mineral particles drown. 

Froth-flotation is an extensively used separation technique, having a wide range of applications in the minerals processing industries and other industries. It can be used for particles in the size range from 50 to 400 //m. 

Separation of milled solid materials is usually based on differences in their physical properties. Of the various techniques to obtain ore concentrates, those of froth flotation and agglomeration exploit differences in surface activities, which in many cases appear to involve the formation of complexes at the surface of the mineral particles. Separation by froth flotation (Figure 4) depends upon conversion of water-wetted (hydrophilic) solids to nonwetted (hydrophobic) ones which are transported in an oil-based froth leaving the undesired materials (gangue) in an aqueous slurry which is drawn off from the bottom of the separator. The selective conversion of the ore particles to hydrophobic materials involves the adsorption of compounds which are usually referred to as collectors. 4... 

Abstract This chapter reviews the development of froth flotation achieved in the past one hundred years and accounts for the achievements of the theory of flotation of sulphide minerals in four aspects, which are the natural flotahility of sulphide minerals, the role of oxygen in the flotation of sulphide minerals, the interaction of collectors with sulphide minerals, the effect of the semi-conductor property of sulphide minerals and electrochemical behaviors in the grinding system. Furthermore, the purpose of this book is revealed in the end. 

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