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Topic: Cyanide process

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	Cyanide - Wikipedia, the free encyclopedia
		In plants, cyanides are usually bound to sugar molecules in the form of cyanogenic glycosides and serve the plant as defense against herbivores.
		Cyanides were stockpiled in both the Soviet and the United States chemical weapons arsenals in the 1950s and 1960s.
		The cyanide compound sodium nitroprusside is occasionally used in emergency medical situations to produce a rapid decrease in blood pressure in humans; it is also used as a vasodilator in vascular research.
	en.wikipedia.org /wiki/Cyanide (3104 words)

	Use in Mining
		Cyanide is manufactured and distributed for use in gold mining industries in a variety of physical and chemical forms, including solid briquettes, flake cyanide and liquid cyanide.
		The cyanide solution is fed from the storage tank into the metallurgical process stream in proportion to the dry mass of solids in the process stream.
		Typical cyanide concentrations used in practice range from 300 to 500 mg/l (0.03 to 0.05% as NaCN) depending on the mineralogy of the ore. The gold is recovered by means of either heap leaching or agitated pulp leaching.
	www.cyanidecode.org /cyanide_use.php (1807 words)

	Gold cyanidation - Wikipedia, the free encyclopedia
		Gold cyanidation (also known as the cyanide process or the MacArthur-Forrest Process) is a metallurgical technique for extracting gold from low-grade ore by converting the gold to water soluble aurocyanide metallic complex ions.
		The original discovery of gold cyanidation was made in 1783 by the chemist Carl Wilhelm Scheele, the discoverer of cyanide.
		The modern cyanide process, the MacArthur-Forrest Process, was developed in Glasgow, Scotland in 1887 by John Seward MacArthur, funded by the brothers Dr Robert and Dr William Forrest.
	en.wikipedia.org /wiki/Cyanide_process (677 words)

	NationMaster - Encyclopedia: Gold mine (Site not responding. Last check: 2007-11-01)
		Cyanide process extraction of gold may be used in areas where gold-bearing rocks or finer material is found at the surface.
		Sodium cyanide solution is allowed to leach through a pile of finely-ground rock that has proven to contain gold and silver, and is then collected as gold cyanide and silver cyanide solution.
		The cyanide technique is very simple and straightforward to apply, and popular in areas where mine tailings may contain surprisingly large quantities of valuable metals despite already having been processed, even with previous treatments with cyanide.
	www.nationmaster.com /encyclopedia/Gold-mine (715 words)

	Got Cyanide Advertisement
		This process allows the gold to be removed from ore that has as little as 0.015 ounces of gold for an entire ton of ore. Hundreds of tons of ore must be mined to create one wedding band.
		In fact, it is this process which has allowed the creation of the huge open pits, such as the pit pictured to the left, which lead to the devastating environmental impacts documented throughout this website.
		A cyanide spill from an overflowing tailings dam at a mine in Romania on January 30, 2000, killed thousands of tons of fish and rendered a significant portion of the Tisza River undrinkable and effectively dead.
	www.greatbasinminewatch.org /gotcyanide.html (821 words)

	ATSE - Samarin (Site not responding. Last check: 2007-11-01)
		Both are used in the cyanide process of separating gold and silver from their ores, in electroplating and in the hardening of steel (liquid carburising).
		The cyanide process invented in 1887 by J S MacArthur, R W and W Forrest, was at first received with certain degree of derision, as at that time cyanide was best known mainly as a deadly poison and its properties were not yet thoroughly studied.
		In the process, pulverised gold ores or tailings from a cheap but inefficient amalgamation process, which was commonly in use in the middle of the 19th century, are mixed with a dilute solution of potassium cyanide (KCN) or sodium cyanide (NaCN) in water.
	www.atse.org.au /index.php?sectionid=437 (1862 words)

	cyanide - HighBeam Encyclopedia (Site not responding. Last check: 2007-11-01)
		Cyanides are salts or esters of hydrogen cyanide (hydrocyanic acid, HCN) formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radical (e.g., ammonium or ethyl).
		They are used as insecticides, in making pigments, in metallurgy (e.g., electroplating and case hardening), and in refining gold and silver by the cyanide process.
		The ethyl ester of hydrogen cyanide (CH CN) is called variously ethyl cyanide, propionitrile, propane nitrile, nitrilopropane, and cyanoethane; propane nitrile is the approved name in the nomenclature system for organic chemistry adopted by the International Union of Pure and Applied Chemistry (IUPAC).
	www.encyclopedia.com /html/c1/cyanide.asp (374 words)

	cyanide process - HighBeam Encyclopedia
		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 cyanide process was developed (1887) by J. MacArthur and others in Glasgow, Scotland.
	www.encyclopedia.com /html/c1/cyanidep.asp (331 words)

	Gold and cyanide EB (Site not responding. Last check: 2007-11-01)
		The process was invented in 1887 by the Scottish chemists John S. MacArthur, Robert W. Forrest, and William Forrest.
		With ores of higher gold content (i.e., greater than 20 grams of gold per ton of ore), cyanidation is accomplished by vat leaching, which involves holding a slurry of ore and solvent for several hours in large tanks equipped with agitators.
		In the latter process, the gold-bearing solution is deoxygenated and passed through a filter-press, where the gold is displaced from solution by reduction with zinc metal powder.
	www.gaiaguys.net /Gold_and_cyanide_EB.htm (407 words)

	from Outside the U.S.: Cyanide in Mining
		Cyanide Leaching Bill 2004 would prohibit the recovery of gold, silver and other metals by cyanide leaching of ore in new mining projects such as the Cowal Gold project.
		Cyanide has been a boon to the mining industry, but a bane to the environment, not only in Eastern Europe - where a spill of cyanide at a Romanian gold mine last week devastated aquatic life in the Tisza and Danube rivers - but in South America and the United States, too.
		Cyanide is used to dissolve the gold, which is extracted by crushing, gravity separation and other physical techniques.
	www.alphacdc.com /treaty/cyanide3.html (10795 words)

	NON-CYANIDE SILVER PLATING
		Using a non-cyanide plating process reduces the volume of hazardous waste generated and the associated disposal costs, and exposure of personnel to hazardous materials and wastes.
		The disadvantages of cyanide-based plating are that cyanides are hazardous to personnel, require frequent bath solution change-outs due to limited bath life, and the generation of rinse streams containing high concentrations of metals and cyanides.
		In particular, the process is unsuitable for nickel-plated parts, parts that have a tarnish resistance requirement, and parts that require a high thickness of silver deposit.
	p2library.nfesc.navy.mil /P2_Opportunity_Handbook/1_10.html (764 words)

	billingsgazette.com
		Use of cyanide to separate gold and silver from rock may be "all right in a state where there's no water," Roos said.
		The process at issue involves rinsing piles of crushed rock with cyanide, a potent chemical that percolates through the rock and draws out small deposits of gold or silver.
		Three major mines in the state used the cyanide process before the 1998 ban, but with gold prices in decline they stopped mining shortly before it took effect.
	www.billingsgazette.com /index.php?id=1&display=rednews/2004/11/02/build/state/20-cyanide.inc (530 words)

	Pollution Prevention in the Plating Process (Site not responding. Last check: 2007-11-01)
		Process baths that generate mist (e.g., hexavalent chromium plating baths and air-agitated nickel/copper baths) should be in tanks that have more freeboard in order to reduce the amount of mist in the ventilation system.
		Cyanide baths are adversely affected by the formation of carbonate buildup during the breakdown of cyanide.
		A copper cyanide plater reported that its RO unit recovered 98 to 99 percent of the copper from its plating wastes and 92 to 98 percent of the cyanide.
	www.p2pays.org /ref/03/02454/plating.htm (15693 words)

	The cyanide leaching process - Bodie.com (Site not responding. Last check: 2007-11-01)
		Eventually the larger pieces were played out, and a new process was needed to collect the tiny fragments that were embedded into hard rock.
		Mixing the tailings with a cyanide solution, or simply spraying the tailings with a cyanide solution, would cause a chemical reaction to take place.
		Another chemical reaction is put to work to separate the cyanide solution from the liquid gold and silver.
	www.bodie.net /st/cyanide.asp (267 words)

	A Physicochemical Study of the Black Cyanide Process (Site not responding. Last check: 2007-11-01)
		The various proposed reaction mechanisms in the literature for the fl cyanide process were evaluated.
		In addition, the standard free energy changes for the reaction of calcium cyanamide and calcium cyanide with water were determined and were used to explain the effect of moisture on the grade of the fl cyanide.
		On the basis of the present study, possible improvements to the fl cyanide process are discussed.
	pubs.nrc-cnrc.gc.ca /cmq/29941-3.html (496 words)

	New Report Looks At Holes In Cyanide Regulations At Mine Sites
		Processing chemicals such as cyanide have made it profitable to mine ore bodies with low ore grades.
		Mines that use cyanide as a processing agent often lead to conflicts over the use of land and natural resources such as water.
		The recent history of cyanide spills is fostering growing public concern about the potential for more spills and accidents, leading to massive water pollution problems.
	www.nocrandonmine.com /wsn/mining/decodingcyanide.html (531 words)

	State joins mining association in lawsuit over cyanide process
		Partly at issue in the lawsuit is whether the county can ban cyanide heap leach mining, used to profitably extract gold from low-grade ore. The toxic chemicals used for heap leach mining can have devastating environmental impacts if the process goes awry.
		Backers of the Summit County ban have said such regulations are crucial for the long-term protection of natural resource assets, which form the basis for the county's tourism-based economy.
		In January 2005, shortly before the county's deadline for responding to the CMA's opening brief in the case, the Colorado Attorney General's Office entered the legal fray, allying itself with the CMA on behalf of the Colorado Mined Land Reclamation Board.
	www.minesandcommunities.org /Action/press608.htm (773 words)

	PF Online Feature Article: Switch to Alkaline Non-Cyanide Zinc Pays Off
		It was difficult to decrease carbonates, and it was expensive to purchase and dispose of the bath.
		Nick Kaplafka, project engineer, was assigned to design a process to treat the carbonates as well as solve the other problems.
		With the new process, it has nearly doubled its load to 160 to 200 pieces per bar.
	www.pfonline.com /articles/099505.html (644 words)

	Gold Mining
		Hard rock mining is most consistent with the popular conception of removing rock from the ground, in which miners tunnel and blast into rock, seeking hydrothermal deposits or sedimentary deposits of gold.
		Veins of gold ore are often found several inches or feet wide in certain rock formations in a hydrothermal deposit and in certain bedding planes or rock strata in a sedimentary deposit, hence the minerals may be removed, collected, and treated to process the gold and other valuable metals (such as silver) from them.
		Sodium cyanide solution is allowed to leach through a pile of finely-ground rock that contains gold and silver, and is then collected as gold cyanide and silver cyanide solution.
	www.cupel.com /gold_mining.html (512 words)

	Search Results for "Cyanide process"
		It is then mixed with a dilute solution...
		...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.
		...Cyanides are salts or esters of hydrogen cyanide (hydrocyanic acid, HCN) formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radical (e.g.,...
	bartleby.com /cgi-bin/texis/webinator/65search?query=Cyanide+process (302 words)

	Crandon Mine Owner Has Spilled Cyanide At U
		The owner of the proposed Crandon mine was responsible for 31 spills of hazardous materials including cyanide, arsenic, and sulfuric acid during a four-year span at three mining operations in Nevada and Arizona.
		BHP spilled 1,500 gallons of sodium cyanide at its Pinto Valley mine in Arizona in September 1996.
		This type of ore processing is the same as is proposed for use at the Crandon mine.
	www.nocrandonmine.com /wsn/mining/BHPspill.html (826 words)

	cyanide process
		refining - refining, any of various processes for separating impurities from crude or semifinished materials.
		cyanide - cyanide, chemical compound containing the cyano group, -CN.
		metallurgy: Separation of the Metal - Separation of the Metal Processes for separating the metal from the impurities it is found with or...
	www.infoplease.com /ce6/sci/A0814376.html (269 words)

	Cyanide process - TheBestLinks.com - Colorado, Complex ion, Chemical reaction, Controversy, ...
		Cyanide process - TheBestLinks.com - Colorado, Complex ion, Chemical reaction, Controversy,...
		Cyanide process, Colorado, Cyanide, Complex ion, Chemical reaction, Controversy...
		A different commercial method that does not use toxic cyanide (http://www.yestech.com/tech/gold1.htm)
	www.thebestlinks.com /Cyanide_process.html (357 words)

	billingsgazette.com
		HELENA (AP) - Opponents of an initiative to overturn Montana's ban on using cyanide in gold and silver mining have formed a group to try to defeat the measure on the November ballot.
		Efforts to develop the gold project and eventually use cyanide to leach the metal from ore ceased when voters passed the cyanide ban, Initiative 137, in 1998.
		Critics of the cyanide process in open-pit mining say it puts the environment at risk, but supporters say the technology is safe if precautions demanded by I-147 are taken.
	www.billingsgazette.com /index.php?display=rednews/2004/07/30/build/state/55-cyandie-initiative.inc (385 words)

	Boise Weekly - Not Your Everyday Newspaper: News: News: Goodbye Cyanide, Hello Mystery Process
		After a long and contentious public comment process, Desert Mineral Mining received a permit last spring to build a cyanide-leaching gold mill 20 miles east of Boise.
		Now the company has decided to abandon the cyanidation process, opting for an obscure mining technique that will allow them to process a far greater amount of ore than they were previously allowed--and with a fraction of the governmental oversight.
		In any event, since the company is not planning to use their permit, Schuld said, the approximately $38,000 that the DEQ spent developing it will likely end up a waste.
	www.boiseweekly.com /gyrobase/Content?oid=oid:157300 (571 words)

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