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cyanide process

cyanide 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. It is then mixed with a dilute solution of sodium cyanide (or potassium or calcium cyanide) while air is bubbled through it. The gold is oxidized and forms the soluble aurocyanide complex ion, Au(CN) ₂^-1 . (Silver, usually present as an impurity, forms a similar soluble ion.) The solution is separated from the ore by methods such as filtration, and the gold is precipitated by adding powdered zinc. The precipitate usually contains silver, which is also precipitated, and unreacted zinc. The precipitate is further refined, e.g., by smelting to remove the zinc and by treating with nitric acid to dissolve the silver. The cyanide process was developed (1887) by J. S. MacArthur and others in Glasgow, Scotland. It is now the most important and widely used process for extracting gold from ores.

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	You can quote us on that: a stock market flotation brings with it a whole raft of new responsibilities for a company's management team, but the technical regulations could turn out to be the least of its worries. Mike Brooks describes the oft-conflicting stakeholder interests that need to be considered before a business goes public.(How To Manage Going Public) Magazine article from: Financial Management (UK); 10/1/2004; ; 700+ words ; ...fall into a number of categories. They may see the flotation as a chance to realise some of their investment. Where...the employees should have nothing to fear from a flotation. Indeed, they might well benefit, both from the potential...possible of the timescale and the structure of the flotation. The ... Read more
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	New process cuts costs for mining companies: Technology eliminates use of copper sulphide in mineral collection process. (Tech Scene).(Brief Article) Magazine article from: Northern Ontario Business; 3/1/2002; ; 572 words ; ...for mining companies. The process being researched could also...environment than conventional processes. Inder Nirdosh, a chemical...expensive chemical in the flotation process for zinc. Nirdosh has also...produced at various mines by flotation, Leroux explains. Unlike... Read more

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Related entries from encyclopedias, dictionaries, and thesauruses

	froth-flotation process Book article from: The Columbia Encyclopedia, Sixth Edition see flotation process . Read more
	flotation process Book article from: The Columbia Encyclopedia, Sixth Edition in mineral treatment and mining, process for concentrating the metal-bearing mineral...removed, leaving a clean concentrate. The process, also called the froth-flotation process, is used for a number of minerals, especially... Read more
	flotation Book article from: A Dictionary of Business and Management flotation The process of launching a public company for the first time...offer for sale , placing , or public issue . After flotation the shares can be traded on a stock exchange. Flotation allows the owners of the business to raise new... Read more
	flotation separation Book article from: A Dictionary of Earth Sciences flotation separation A concentration process where by finely ground ore is dispersed in water containing a flotation reagent which causes selected minerals to become hydrophobic...floating particles are skimmed off or overflow the flotation cell. Read more
	beneficiate Book article from: A Dictionary of Earth Sciences beneficiate To increase the grade of ore after grinding by a concentration process, such as froth flotation or gravity, or by magnetic, electrostatic, or other methods. The term also implies the elimination of waste material. See FLOTATION SEPARATION . Read more

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