refining


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refining,

any of various processes for separating impurities from crude or semifinished materials. It includes the finer processes of metallurgy, the fractional distillation of petroleum into its commercial products, and the purifying of cane, beet, and maple sugar and many other substances. The nature of the refining process depends on such factors as the type of material involved, the value of the end product, and the degree of purity necessary. The purification of a metal is based upon physical or chemical differences between the metal and its accompanying impurities, including density, melting point, magnetic properties, and reaction to certain chemicals. It may be accomplished by a continuation of a process used in separating the metal from its ore. Electrolysiselectrolysis
, passage of an electric current through a conducting solution or molten salt that is decomposed in the process. The Electrolytic Process

The electrolytic process requires that an electrolyte, an ionized solution or molten metallic salt, complete an
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 is much used in the refining of various metals (e.g., copper); the open hearth process (see steelsteel,
alloy of iron, carbon, and small proportions of other elements. Iron contains impurities in the form of silicon, phosphorus, sulfur, and manganese; steelmaking involves the removal of these impurities, known as slag, and the addition of desirable alloying elements.
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) and the basic oxygen processbasic oxygen process,
method of producing steel from a charge consisting mostly of pig iron. The charge is placed in a furnace similar to the one used in the Bessemer process of steelmaking except that pure oxygen instead of air is blown into the charge to oxidize the impurities
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 are used in the refining of iron; the amalgamation processamalgamation process
, in particular, a method to extract gold and silver from ores. The ore is crushed and treated with mercury, in which the metal dissolves. The amalgam is heated and the mercury evaporates, leaving pure gold or silver.
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 and the cyanide processcyanide process
or cyanidation,
method for extracting gold from its ore. The ore is first finely ground and may be concentrated by flotation; if it contains certain impurities, it may be roasted.
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 are chemical means of metal refining.
References in periodicals archive ?
Under the deal Western Refining shareholders will get 0.
Summary of key issues arising from the changing levels of refining capacity in different regions
For example, the amount of titanium present in the spectrographic analysis can be used effectively as a quality control tool to verify that the grain refining process is consistent.
com to read about ECS Refining and United Datatech's experiences under California's Electronic Waste Recycling Act of 2005.
Many companies cut investment in refining activities because the line of business generated very low financial returns.
Officials said state government spent more than $230,000 investigating and pursuing cleanup of contaminated soil at the Commodity Refining Exchange plant, 11817 United Street.
For maximum effectiveness, grain refining should be performed as close to the point of pour as possible.
The effect of refining on the recycled chemical bleached pulps of bagasse and wheat straw has been evaluated.
Faster melting gives Express Metal Refining more production capacity without adding costs and allows it to turn around its inventory taster, which is crucial when gold market prices are volatile, as they frequently are.
In this study, we evaluate the specific incidence of selective refining actions on a repulped unbleached long-fiber kraft paper.