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.

LITERATURE REVIEW AND THERMODYNAMIC MODELING …

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 ...

Test work to examine the potential for improving gold …

The unsatisfactory extraction in the leach section could be attributed to: The presence of sulphides like pyrrhotite and arsenopyrite, which can consume cyanide as well as oxygen …

Improvements in gold ore cyanidation by pre-oxidation with …

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% ...

Advances in the Cyanidation of Gold

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 ...

The effect of grinding chemistry on cyanide leaching of gold …

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 ...

Kibali Gold Mine sulphide concentrate treatment – …

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 …

Effect of pyrrhotite reactivity on cyanidation of pyrrhotite produced by pyrolysis of a sulphide ore

The results of the foregoing tests show that intense aeration of pyrrhotite in a strongly alkaline solution reduced the cyanide consumption by 4 to 5 lbs. of NaCN/ton of …

Pyrrhotite

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 ...

Reactions of gold and sulfide minerals in cyanide media

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 …

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. ...

Process of Cyanide Gold Extraction

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 ...

The effects of dissolved oxygen and cyanide dosage on gold …

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, …

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 reactivity. …

Characterization of jarosite formed during biooxidation of …

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 ...

Increasing leaching rate of gold cyanide of two-stage

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 pretreatment parameters considered were …

Gold recovery from a refractory pyrrhotite ore by biooxidation

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 ...

A comparative study of the dissolution of hexagonal and …

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].

INFLUENCE OF LEAD NITRATE ON CYANIDE LEACHING …

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

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 …

Incorporation of Geometallurgical Input into Gold Mining …

Although Florida has not observed pyrrhotite and marcasite as being major contributors to increased cyanide consumption, it has nonetheless been reported that ferrocyanide ions do have an inhibiting effect on gold cyanidation . This can be explained by the additional consumption of oxygen and cyanide required for the formation of ferrocyanide ions.

(PDF) Experimental Study on the Dressing and Smelting of a Pyrrhotite …

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 effect of sulfide minerals on the leaching of gold in …

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.

Reactions of gold and sulfide minerals in cyanide media

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 various concentrations of sulfides ... tailings is strongly influenced by the consumption of cyanide (Deschenes and Prud'homme, 1997; McMullen et aI., 1999 ...

Comparative study of the dissolution of hexagonal …

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).

KINETIC MODELLING OF GOLD LEACHING AND CYANIDE CONSUMPTION …

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 ...

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. ...

Experimental Study on the Dressing and Smelting of a …

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.

(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).

Effect of the composition of some sulphide minerals on …

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 ...

A review on the negative impact of different elements …

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 …

Gold recovery from a refractory pyrrhotite ore by biooxidation

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 ...

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. ...

The Use of Oxygen in Gold Cyanidation

It can be deduced from Fig. 3 that the lowest cyanide consumption is established with low "free" cyanide concentration (50 ppm) and a leaching pH of 10.8. The high cyanide consumption at high "free" cyanide concentration and loa leaching pH is associated with HCN evolution, which is f;jvoured with both high cyanide concentration and low PH.

Lead Oxide Enhances the Leaching of Gold in Cyanide …

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.

Incorporation of Geometallurgical Input into Gold Mining …

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 ...

Characterization of jarosite formed during biooxidation of …

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 ...

Effect of lead nitrate addition on the leaching of a 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. ...