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The results obtained thus suggest the 70% grind passing 75 µm ore with the gold dissolution percentage very close to the conventional 80% passing size at the lowest cyanide consumption of 500 ppm, much lower daily power consumption of about 925 kWh and high residual lime content that indicated the minimization of cyanide loss as hydrogen ...
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The possible loss of cyanide ion through the formation of such stable complexes as those indicated above increases the costs associated with reagent consumption, and is a major variable in the financial viability of a gold operation [20].Such concerns have been repeated in a variety of reviews on gold treatment by cyanidation [1], [21], [22].
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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 solution ...
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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 reactivity. …
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In addition, the presence of sulphides leads to extra consumption of the cyanide-leaching agent, NaCN, due to the formation of thiocyanate, therefore increasing costs. ... ore feeding the leaching circuit averages 1.70 g Au/t and the main oxygen-consuming component is the sulphide mineral pyrrhotite (FeS) at about 2.5% ...
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The results showed that pyrrhotite has the greatest effect on cyanide leaching in iron minerals, which decreases gold dissolution rate by 28.1% and increases cyanide consumption by 4 times....
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It was also noted that the lowest average percents cyanide consumption of 62.91, 61.73 and 58.56 at 60, 70 and 80% passing 75 µm were obtained at the 500 ppm cyanide concentrations. It was further observed that a clear pattern of increasing residual lime content was only observed at the 70% grind size, with the least lime content of 150.37 ppm ...
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hours leaching by the addition of lead nitrate as 0.1-0.5 kg/Mg. NaCN consumption decreased or did not change except for the Ovacik ore. In the case of the Ovacik ore it slightly increased. Keywords: lead nitrate, gold, silver, cyanide leaching Introduction Extraction of gold from its ores by cyanide leaching has been the preferred method for
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Pyrrhotite is a type of Fe-S mineral commonly found in base metal sulfide deposits. It has a significant impact on the recovery of valuable metals and must be removed during the beneficiation process. Pyrrhotite can have different structures, such as monoclinic and hexagonal, with different magnetic properties. ... Cyanide consumption decreased ...
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Pyrrhotite is the most reactive and the highest cyanide and oxygen consuming iron sulphide mineral due to the formation of Fe(OH) 3 and SCN − Hedley and Tabachnick, 1968, …
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Cyanide and lime consumption are reported in kg/t of concentrate with typical flotation mass pulls of between 10 and 11%. Under these conditions of lower concentrate head grade (21 g/t), concentrate leach residue grades as low as 2 …
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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 ...
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The cyanide consumption by the pyrite mixture (9.7% pyrite) was 7 times higher than for the pyrrhotite (1.23 kg/t vs. 0.17 kg/t). Chalcopyrite was the most soluble mineral with a …
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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.
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The effect of pyrite, pyrrhotite, chalcopyrite, realgar and arsenopyrite on gold dissolution in cyanide media was investigated. The cyanidation of synthetic gold ores in the presence of …
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al. (1984) and Grano et al. (1990). Cyanide decreases the rate and degree of xanthate adsorption on iron sulphides, especially on pyrrhotite, and leads to desorption of xanthate preliminary adsorbed on their surfaces (Prestidge et al., 1993). However, no cyanide species were detected on pyrite (Leppinen et al.,
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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 Au % and 88.0 ...
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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 …
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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. ...
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The consumption of cyanide during processing operations is a major economic cost in the extraction of gold from its ores, while the discharge of cyanide wastes may result in significant environmental pollution. ... (III) hydroxide, reducing gold particle coating and leaching efficiency. Iron sulfide, particularly pyrrhotite, consumes cyanide ...
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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. ...
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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 …
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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. ... such as pyrrhotite and pyrite. The presence of these reactive sulphides often inhibits gold dissolution by ...
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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 ...
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Some pyrrhotite intergrowths with other sulphide minerals such as chalcopyrite and sphalerite also ... Cyanide consumption ranged from 1.6 to 2.2 kg/t whereas lime ranged from 2.5 to 3.2 kg/t. Cyanidation of the tails recovered 50% Au and 40% Ag, with Sodium cyanide and lime consumption 0.7 kg/t and 1.5 kg/t respectively. ...
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Consumption of cyanide in these experim ents was in the range of 4-7 kg/t. Kinetic curves of oxidation of flotation c oncentrate are shown in Figures 8-9: Bio without grindeng
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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
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It was reported that pre-leaching successfully overcame the effect of pyrite and pyrrhotite on cyanide consumption and the gold leaching kinetics, but it had no beneficial effect when chalcopyrite was present. It was suggested that lead nitrate prevented copper and iron dissolution by forming a passive layer at the surface of sulfide minerals.
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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 consumption ...
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It contains 99% sulphides of which 10 to 20 percent is pyrrhotite and 0.3 to 0.7% chalcopyrite, the remainder being mostly pyrite. The gold content is 0.10 to 0.13 oz. per ton, none of which is free; the gold particles are attached to pyrite, and in general they are less than 1 micron in size. ... Cyanide consumption is about 2 lbs. NaCN per ...
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Fe-bearing sulfides, such as pyrite marcasite and pyrrhotite decompose in cyanide solutions, increasing oxygen consumption and decreasing the dissolution kinetics of gold (Habashi, 1987). Also, cyanide forms complexes on the iron sulfide mineral surfaces, and remove CN – from the solution.
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Marcasite and pyrrhotite will react with cyanide and form iron cyanocomplexes, soluble sulphide ions (S2− ), and thiocyanate ions as major undesirable products. ... Cyanide consumption simulation plots based on modes of operation, relative ore proportions, and average consumption requirement for each ore type (Ore1 = 2.24 kg/t, Ore 2 = 1.75 ...
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Three approaches have proved to be very efficient in reducing cyanide consumption in gold plants and reducing the cost of effluent treatment for cyanide destruction: the use of an online cyanide analyzer, oxygen enrichment of the pulp and the addition of lead nitrate (or litharge). ... However, the presence of reactive pyrrhotite resulted in a ...
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Cyanide consumption decreased slightly by approximately 8%. ... it was found that pyrrhotite did not generate a high cyanide consumption while pyrite and chalcopyrite were detrimental. Pre ...
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Hereafter, the term refractory will refer to ores whose mineralogical characteristics lower the efficiency of leaching processes (De Michelis et al., 2013, Fleming, 1992), either because cyanidation results in a low precious metal extraction or due to an excessive cyanide consumption (Deschênes et al., 2011), which can eventually turn the process unviable …
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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. ...
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