Segregation, physical

Shinbrot, T. Muzzio, F.J. Non-equilibrium patterns in granular mixing and segregation. Physics Today, March, 2000 25-30. 

The initial step in the recycle of metals is the physical segregation of the metals from other materials. Eor new scrap this process is straightforward for old scrap it can be expensive. This classification and segregation of scrap is of importance to the producers of the metals from secondary materials. Historically, much of the classification has rehed on hand sorting which can be rehable, but it is labor intensive. The recycling of automotive scrap is illustrative of the... 

A uniform coating of calcium carbonate deposited on the metal surfaces physically segregates the metal from the corrosive environment. To develop the positive LSI required to deposit calcium carbonate, it is usually necessary to adjust the pH or calcium content of the water. Soda ash, caustic soda, or lime (calcium hydroxide) may be used for this adjustment. Lime is usually the most economical alkaH because it raises the calcium content as weU as the alkalinity. 

Recent advances in accelerator technology have reduced the cost and size of an RBS instrument to equal to or less than many other analytical instruments, and the development of dedicated RBS systems has resulted in increasing application of the technique, especially in industry, to areas of materials science, chemistry, geology, and biology, and also in the realm of particle physics. However, due to its historical segregation into physics rather than analytical chemistry, RBS still is not as readily available as some other techniques and is often overlooked as an analytical tool. 

Part (c) considers the mixing extremes possible with the physical arrangement of two tanks in series. The two reactors could be completely segregated so one limit remains 0.233 as calculated in part (b). The other limit corresponds to two CSTRs in series. The first reactor has half the total volume so that Uinkii = 2.5. Its output is 0.463. The second reactor has (ai )2ki2 = 1.16, and its output is 0.275. This is a tighter bound than calculated in part (b). The fraction unreacted must lie between 0.233 and 0.275. 

Set up procedures to prevent inadvertent introduction of other ignition sources and to avoid oxygen enrichment Physical segregation, e.g. fences... 

Since nanoscale metal nanoparticles are applicable to a number of areas of technological importance, the nano-structured materials chemistry will occupy much attention of scientists. It is certain that controlling the primary structures of metal nanoparticles, that is, size, shape, crystal structure, composition, and phase-segregation manner is still most important, because these structures dominate the physical and chemical properties of metal nanoparticles. Now the liquid phase synthesis facilitates the precise control of the primary structures. 

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