separation(redirected from Acromioclavicular separation)
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separationSymbol: ρ. The angular distance between the two components of a visual binary or optical double star. Separation can be measured with a filar micrometer in the eyepiece of the telescope; its value is expressed in arc seconds (″).
in analytical chemistry, any one of a number of methods used to detect and quantitatively analyze a given element or substance found in a complex material. Separation methods are important because most analytical methods are not sufficiently selective. Group reagents simplify the difficult analysis of complex mixtures and, as a result, are used to separate ions found in elements. Separation methods include precipitation, extraction, chromatography, and distillation.
any of the processes used in separating the components of mixtures of heterogeneous solid particles, mixtures of liquids of various density, emulsions, or suspensions of solid particles or droplets in gases or vapors. The components to be separated do not change their chemical composition. For example, a mixture of mineral grains upon separation is divided into products consisting of the same minerals in different quantitative ratios. Separation is based on differences in the physical or physicochemical properties of the components of a mixture. These differences include the size of the solid particles, shape, color, luster, coefficient of friction, strength, elasticity, surface wettability, magnetic susceptibility, electrical conductivity, luminescence, and radioactivity.
In the concentration of minerals, almost all the operations, including screening and classification, can be regarded as forms of separation. Variants include air-actuated, or pneumatic, separation, heavy-media separation, magnetic separation, flotation separation, electrical separation, triboadhesive separation, radiometric separation, friction separation, and elasticity separation.
In agriculture, the operations for separating grains during processing are also called separation. Grains can be separated according to grain size, shape, density, coefficient of friction, elasticity, and magnetic susceptibility.
The properties that are to distinguish the products of separation do not always coincide with the characteristics that can be used in effecting the separation. For example, in the separation of coal from rock materials, products having the same densities may have different amounts of ash, which determines the quality of the coal. In order to select a means of separation, the composition of the mixture to be separated is studied, as are the properties of the components and the extent of the correspondence between the desired characteristics and the properties that make possible a separation. Separation in most cases is based not on one major property distinguishing the components but on a series of properties. Thus, separation depends on the conditions of the operation and on the apparatus (separator) in which the process is performed. For example, in air separation by size, fine particles must be carried in an air stream, and the results of the separation are determined not only by the size of the particles but also by particle density and shape. A large number of individual particles (grains) take part in separation; these include particles with properties with intermediate properties relative to the major characteristic. As a result, industrial separation of an initial mixture does not yield pure fractions of the separated substances but rather products having a composition that is predominantly of one component.
REFERENCESBarskii, L. A., and I. N. Plaksin. Kriterii optimizalsii razdelitel’nykh protsessov. Moscow, 1967.
Spravochnik po obogashcheniiu rud, vols. 1–3. Moscow, 1972–74.
Gortinskii, V. V., A. B. Demskii, and M. A. Boriskin. Protsessy separirovaniia na zernopererabatyvaiushchikh predpriiatiiakh. Moscow, 1973.
Spravochnik po obogashcheniiu uglei. Moscow, 1974.
V. A. PEROV
ii. The breakdown of the laminar attached flow in fluids into a gross turbulent flow occurring at a particular time and place. See separation point.
iii. The distance between a target and the interceptor along any axis.