The content of pyrrhotite in a primary gold mine containing pyrrhotite is 0.68%. In the process of alkaline leaching pretreatment, there are problems such as large ore quantity and high alkali ...
The aim of the present investigation was to study the biooxidation of a refractory gold-bearing pyrrhotite, in order to increase the gold recovery during the subsequent conventional cyanidation.Bacterial cultures utilised in the biological test consisted predominantly of Thiobacillus genus. ... Contribution of metal ions to cyanide …
Abstract. The content of pyrrhotite in a primary gold mine containing pyrrhotite is 0.68%. In the process of alkaline leaching pretreatment, there are problems such as large ore quantity and high alkali consumption. In the process of cyanide leaching, there are problems such as high cyanide consumption and slow gold leaching rate.
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. ...
cyanide: Pyrrhotite >>> Marcasite > Arsenopyrite > Pyrite The addition of lead nitrate could have resulted in the passivation of these cyanide consumers, resulting in a ... resulted in an 11.9 g/t decrease in cyanide consumption. This is probably due to the fact that less cyanide is lost as hydrogen cyanide gas at higher pH values. At a pH of ...
Here a clear decrease in cyanide consumption is observed with increasing temperature of pyrrhotite formation, regardless of whether there was complete or incomplete conversion of pyrite to pyrrhotite. 45 O '7 O O L~ 40 35 3O 25 20 15 10 5 0 750 II I I I I 850 950 1050 1150 Temperature ofpyrrhotite formation / K Fig.5 Cyanide …
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 cyanidation of a pyrrhotite-bearing gold ore indicated that direct cyanidation could not effectively leach the gold (Deschenes and Fulton, 2002). Pyrite showed a preg-robbing …
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 …
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 pyrrhotite is a common refractory mineral Table 7 Gold recovery by cyanidation, without biological pretreatment or after 7 and 30 ...
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 …
Among the associ-ated iron minerals, pyrrhotite has a significant impact on cyanide leaching of gold. Pyrrhotite can be significantly oxidized during grinding and cyanidation.
The presence of pyrrhotite in gold ores is known to have a negative impact on the dissolution of gold and on the consumption of cyanide. This report presents the results …
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
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 ...
For the gold locked within hematite in the two-stage calcination, which leads to a low gold leaching rate, the present work is aiming at pretreating the calcination to selectively dissolve hematite. The calcination was pretreated by sulfuric acid with cosolvent B. The factors influencing the hematite dissolution rate were studied, and the …
However, the presence of reactive pyrrhotite resulted in a cyanide consumption of 31.5 kg/t NaCN. Three key features were identified to optimize the …
ated iron minerals, pyrrhotite has a significant impact on cyanide leaching of gold. Pyrrhotite can be significantly oxidized during grinding and cyanidation. In the oxidation process, the oxidation products' reaction with CN,O 2 and protective alkali consumes a large amount of dissolved oxygen and CN, thus increasing the cyanide consumption
The extent and rate of dissolution of two natural pyrrhotite samples, one monoclinic (Fe0.88S) and the other hexagonal (Fe0.90S), were studied in alkaline cyanide solutions (pH 10).
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 …
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 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. ...
Pyrite, as the main gold-bearing mineral, significantly impacts the consumption of cyanide, alkali and oxygen in the process of cyanidation. In this study, …
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 …
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.
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 ...
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] .
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 …
Semantic Scholar extracted view of "The effects of dissolved oxygen and cyanide dosage on gold extraction from a pyrrhotite-rich ore" by S. Ellis et al. Skip to search form Skip to ... of a sulphide gold-silver ore was investigated in terms of a relationship between gold and silver extractions and cyanide consumption. Ninity five …
A pre-leaching successfully hinders the effect of pyrite and pyrrhotite on cyanide consumption and leaching kinetics. The pre-leaching has no beneficial effect on chalcopyrite as far as cyanide consumption goes. Additional work has to be conducted on sulphide minerals to characterize the processing parameters required to alleviate their ...
The action of cyanide is stronger on pyrrhotite than on pyrite, which may be linked to the greater solubility of pyrrhotite in cyanide solutions (Osseo-Asare et al., 1984), leading to more iron-cyanide complexation.
De Andrade Lima and Hodouin [6] have studied cyanide consumption in gold cyanidation. They presented a cyanide consumption model in which the rate is a function of cyanide concentration and particle size. -1 1.69 × 10 −8 3.71 cCN − r = 0.547 − 6.40 d (5) where r is in units mg dm-3 h-1 and d is in units µm.
Samples that were partially converted to pyrrhotite, and hence remained in equilibrium with the unconverted pyrite, showed an increase in cyanide consumption with increasing metal to sulphur ratio.
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. ... It should be noted that other factors can also affect the consumption of free cyanide significantly, including the presence of ...
Cyanide consumption increases from 16 kg t −1 (without bioleaching) to about 21 kg t −1 (7 days bioleaching) and to about 22 kg t −1 (30 days bioleaching) (Table 8). This increase can be explained considering that pyrrhotite is a common refractory mineral and its decomposition forms ferrocyanide which removes free cyanide from …
