(PDF) LITERATURE REVIEW AND THERMODYNAMIC …
Cyanide consumption affects both the economics and the environmental impact of the process, as it increases the operating costs and the potential toxicity of the effluents. ... (III) hydroxide, reducing gold particle coating and leaching efficiency. Iron sulfide, particularly pyrrhotite, consumes cyanide and oxygen, forming a stable ...
Effect of pyrrhotite reactivity on cyanidation of pyrrhotite …
The effect of the metal to sulphur ratio in the nonstoichiometic compound, pyrrhotite, is related to the consumption of cyanide in gold leaching. Reactive pyrrhotite (Fe (I-X) S) is produced during the pyrolysis of refractory pyrite (FeS 2). Iron vacancies give pyrrhotite its non stoichiometric nature and determine its fugacity and hence ...
(PDF) Cyanidation of a pyrrhotite-bearing gold ore
Gold. Article PDF Available. Cyanidation of a pyrrhotite-bearing gold ore. January 2003. Authors: G. Deschênes. BBA Inc. D Hall. M Fulton. Citations (8) …
Effect of Cyanide on Steel and How Iron Minerals are Leached by Cyanide
Commencing at about 0.25% NaCN for sands or slimes, cyanide strength falls to about 0.08% NaCN for sand charges, and 0.02% NaCN for pure slime charges, with about equal extraction of gold in each case. Hence, the overproduction of slime increases cyanide consumption. About 0.5 lb. of solid lime per ton of sand is added with the …
The effect of grinding chemistry on cyanide leaching of gold …
Pyrrhotite is of interest to grinding and leaching chemistry because this sulfide mineral is the highest cyanide- and oxygen-consuming iron sulfide and, contrary to pyrite, tends to behave as a reactive anode. ... The selection of grinding media appears to be significant when cyanide reagent consumption is evaluated.
Effect of the composition of some sulphide minerals on …
With regard to the synthetic ores, it was found that pyrrhotite did not generate a high cyanide consumption while pyrite and chalcopyrite were detrimental. …
Fundamentals for optimization of cyanide processes in …
Theoretical substantiation of activation, deactivation and depression processes in flotation of copper-pyrite, copper-zinc and polymetallic ores with the use of cyanide as well as …
Effect of lead nitrate on cyanidation of gold ores: progress …
Gold ore #2 is second for cyanide consumption with 0.33 kg/t. The second gold ore generated higher cyanide consumption than the first gold ore that has 3.1% pyrrhotite, 0.4% pyrite and a cyanide consumption of 0.22 kg/t. It was found in a previous study that pyrite is more detrimental than pyrrhotite for cyanide consumption …
The effect of grinding chemistry on cyanide leaching of …
Pyrrhotite may react with cyanide and oxygen that leads to consumption of cyanide and suppress gold extraction [43][44] [45]. These phenomena might probably affect PGM recovery by caudation. ...
Pyrolysis of arsenopyrite for gold recovery by cyanidation
Figure 8 is a plot of hydroxide and cyanide consumption versus mass loss during cyanidation. Clearly, hydroxide consumption was highly dependent on the mass loss of pyrrhotite while cyanide consumption changed only slightly. This indicates that, under these experimental conditions, more iron precipitated as hydroxide than dissolved …
A comparative study of the dissolution of hexagonal and …
The extent and rate of dissolution of two natural pyrrhotite samples, one monoclinic (Fe 0.88 S) and the other hexagonal (Fe 0.90 S), were studied in alkaline cyanide solutions (pH 10). The effects of dissolved oxygen, particle size, and temperature were investigated. The extent of dissolution was followed by monitoring the dissolved …
Gold Metallurgy & Leaching in Cyanicides
Recovering Gold from Iron Sulphides. While the oxidized iron minerals ordinarily have little effect in cyanidation, the sulphides—pyrite, marcasite and …
Gold recovery from a refractory pyrrhotite ore …
Cyanide consumption increases from 16 kg ty1 Žwithout bioleaching. to about 21 kg y1 Ž t 7 days bioleaching. and to about 22 kg ty1 Ž30 days bioleaching. ŽTable 8.. This increase can be explained considering that …
Effect of the composition of some sulphide minerals on …
While the cyanide consumption for the sulphide-free mixture was almost nil at 0.03 kg/t, the consumption of cyanide was relatively low for the pyrrhotite mixture at 0.14 kg/t. This result is in agreement with the work of Dunn who found a low solubility of pyrrhotite in cyanide solution [13] .
The interaction of cyanide with pyrite, marcasite and pyrrhotite
Pyrrhotite may react with cyanide and oxygen that leads to consumption of cyanide and suppress gold extraction [43] [44] [45]. These phenomena might probably affect PGM recovery by caudation. ...
Pyrrhotite
Pyrrhotite can have different structures, such as monoclinic and hexagonal, with different magnetic properties. Flotation is commonly used to separate pyrrhotite from other minerals. ... Cyanide consumption decreased by approximately 8%. However, without lead nitrate, oxygen cannot be used to process this sulfide-bearing gold ore. ...
Effect of oxygen on gold cyanidation: laboratory results
The cyanidation tests determined the effect of oxygen on leaching rate, total gold dissolution and cyanide consumption. ... [6 ] and, therefore, iron dissolution, which con- sumes cyanide, is higher for pyrrhotite than pyrite. This statement is corroborated by the results from sample H, which has a high pyrite content but the lowest rate of ...
Cyanide Leaching and Decomposition of Pyrrhotite
The effect of the metal to sulphur ratio in the nonstoichiometic compound, pyrrhotite, is related to the consumption of cyanide in gold leaching. Reactive …
Energetics of defect formation and interaction in pyrrhotite …
Iron vacancies give pyrrhotite its non stoichiometric nature and determine its fugacity and hence reactivity. Separate trends for cyanide consumption were found when pyrite was partially converted to pyrrhotite compared to where all the pyrite was converted to pyrrhotite. Samples that were partially converted to pyrrhotite, and hence remained ...
Effect of preoxidation and lead nitrate addition on sodium cyanide …
Since cyanide is an expensive reagent, often a major component of plant operating costs, it is important that the scale-up of cyanide consumption from laboratory to plant be representative.
Cyanidation of a pyrrhotite-bearing gold ore
An electrochemical study indicated that pyrrhotite oxidation is much slower than the cyanidation of gold and is an unlikely reaction to significantly consume dissolved oxygen …
Pyrrhotite
Pyrrhotite crystallises as either a hexagonal or monoclinic structure, both of which can occur in ore deposits. In general, pyrrhotite is not considered as a valuable mineral unless it contains considerable amounts of other metals like nickel or copper. In fact it causes numerous problems in flotation including intensive oxygen consumption, which results …
(PDF) Improvements in gold ore cyanidation by pre …
Considering the period before the trial, the average consumption of sodium cyanide in the five-month period before the industrial trial was 0.52 kg/t. In the five-month period of the peroxide pre-oxidation trial, the average consumption of NaCN fell to 0.40 kg/t – a reduction of 23% (Fig. 1).
Huan Li
Cyanide consumption minimisation and concomitant toxic effluent minimisation during precious metals extraction from waste printed circuit boards. H Li, E Oraby, J Eksteen ... Selective extraction of Ni and Co from a pyrrhotite-rich flotation slime using an alkaline glycine-based leach system. E Oraby, H Li, Z Deng, J Eksteen. Minerals ...
Cyanide-free separation of high pyrrhotite Zn-S bulk concentrate
The consumption of CuSO 4 and lime is greatly reduced in the cyanide-free separation (Table.S2). In addition, the application of MOC makes the discharge of tailings more stable, which greatly avoids the loss of valuable minerals caused by the concentrated discharge of tailings in the cyanide process.
Cyanide Leaching Chemistry & Gold Cyanidation
Not only do copper minerals dissolve in cyanide and cause excessive consumption of this chemical, but also, the copper cyanogen complexes thus formed indirectly affect the dissolution of the gold. ... When sulphide minerals such as covellite, pyrrhotite, sphalerite, etc. are decomposed by, or dissolved in cyanide solutions, some …
Cyanidation of a pyrrhotite-bearing gold ore
A study on hexagonal pyrrhotite indicated a very low solubility in aerated cyanide solutions (Linge, 1995). The transformation of pyrite to pyrrhotite, using pyrolysis, indicated that the cyanide consumption gradually decreases with an increase in the pyrrhotite content of the sample (Browner and Lee, 1998). This
Effect of oxygen and lead nitrate on the cyanidation of a …
The application of lead nitrate in combination with oxygen generated the best results. Gold extraction of 96% can be obtained with cyanide consumption of 0.51 kg/t and lime consumption of 0.60 kg/t in 24 hours. A four hour pre-leach followed by cyanidation is required (free cyanide concentration 480 ppm, pH 10.5, lead nitrate 200 …
(PDF) Cyanidation of a pyrrhotite-bearing gold ore
Pyrrhotite may react with cyanide and oxygen that leads to consumption of cyanide and suppress gold extraction [43] [44][45]. These phenomena might probably affect PGM recovery by caudation. ...
The effects of dissolved oxygen and cyanide dosage on
Clearly the high concentrations of oxygen and cyanide improve initial gold leaching kinetics but high cyanide concentrations also increase cyanide consumption (Ellis and Senanayake, 2004). The use ...