Gold amp; Silver Dissolution and Cyanide Concentration. By far the most important cyanides used in cyanidation are sodium cyanide and calcium cyanide. The latter product is sold in an impure form analyzing close to 50% NaCN equivalent. The former is sold in various grades from 85 to 98% NaCN.
The gold particle size has a tremendous effect on the time required for dissolution in a cyanide solution. Generally, the finer the gold, the quicker it will dissolve. A 45 micron particle of gold would dissolve in 10 13 hours, while a 150 micron particle might take from 20 to 44 hours to dissolve
Capital and ongoing cost benefits. Using sodium cyanide solution also eliminates the use of chemicals, such as caustic soda, to maintain a stable pH level when dissolving solid sodium cyanide. Water quality, in particular salinity, can significantly destabilise the pH balance in the dissolution process.
Dissolution of gold with cyanide replacing reagents 271 Dissolution in thiourea is shown as 3+Au + 2 SC(NH 2) 2 + Fe Au[SC(NH 2) 2] 2 + + Fe2+. (4) The reaction is sensitive to pH and redox potential. Thiourea is intrinsically unstable and decomposes rapidly to substances that are unable to leach gold (Murthy, 1996; Aylmore, 2005)
The salts of sodium, potassium and calcium cyanide are quite toxic, as they are highly soluble in water, and thus readily dissolve to form free cyanide. Operations typically receive cyanide as solid or dissolved NaCN or Ca(CN) 2. Weak or moderately stable complexes such as those of cadmium, copper and zinc are classified as weak acid dissociable (WAD).
Oct 20, 20140183;32;Nature of Gold The surface of a gold particle will typically be dissolved at a rate of around 0.2 0.5 181;m of surface depth per hour in a cyanide leach. For large gold particles and nuggets, this is too slow to be fully dissolved in a typical processing plant. Much simpler and less expensive gravity methods are available to recover this gold.
the dissolution of gold metal during the recycling of electronic and precious metal scrap is performed every day using hazardous chemicals such as sodium cyanide or aqua regia. These chemicals represent health and safety risks for workers and a serious threat for the environment. However, even if several other reagents are known to dissolve gold
May 10, 20190183;32;Since these two reagents are the most promising cyanide alternatives for gold ores, a gold silver alloy was used to see the effect of alloying elements onto the dissolution reaction.
Metallurgical ContentManufacturing CyanideTypes of Cyanide and Cyanide ConsumptionPutting Gold into Solution with CyanideFACTORS IN DISSOLUTION OF GOLD AND SILVERCyanide ConcentrationAlkalinity VariationsDISSOLUTION OF GOLD AS A CORROSION PROCESSDISSOLUTION OF SILVERCyanidation Manufacturing Cyanide Sodium cyanide is a
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