bisulfide gold leaching

New Alternative To Cyanidation: Biocatalyzed Bisulfide Leaching

This paper describes progress in development of an alternative to cyanidation, bisulfide leaching, for extracting gold, silver from refractory ores and concentrates. While bisulfide leaching can be implemented abiolically, significant benefits accrue from its practice as a bioprocess integrating precious-metals liberation and extraction steps.

Alternative Lixiviants to Cyanide for Leaching Gold Ores -

Jan 01, 2016  Initial bisulfide-leaching tests using the YES process attained 25–31% gold extraction from a bio-oxidized Nevada ore compared with 88% by conventional cyanide leaching (Hunter et al., 1998). At the same time, 39–81% silver was recovered compared to 86% with cyanide.

A fundamental study of the alkaline sulfide leaching of gold

gold leaching system, both a complexing lixiviant and an oxidant are required to effect dissolution. It will be shown that sulfide is an effective lixiviant, and the polysulfides are effective ...

(PDF) Fundamentals and applications of alkaline sulfide leaching

INTRODUCTIONAs alkaline sulfide leaching of gold has its roots in the development and industrial application of nitrogen species catalyzed pressure leaching for partial oxidation of sulfides, a discourse in this topic is relevant. ... bisulfide and polysulfide as potential lixiviants for the alkaline sulfide system. The large calculated current ...

Alkaline sulfide gold leaching kinetics - ScienceDirect

Jun 01, 2016  The alkaline sulfide leaching rate of gold was found to be largely temperature dependent, with greater leach rates occurring at higher temperatures. The activation energy of the 50 g L −1 sulfide and 25 g L −1 polysulfide system was 41.6 kJ mol −1 , indicating that the dissolution of gold in this polysulfide/sulfide system is chemically ...

Sulfide/Bisulfide/Sulfite Leaching Sulfur Sulfide

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YES TECHNOLOGIES: Cyanide-free biocatalyzed leaching of ...

More environmentally friendly-- the bisulfide leaching agent used is about 200 times less toxic than cyanide. Since its invention in 1899, cyanidation and its variants have been the processes of choice for extraction of gold and silver from oxidized ores. Cyanide, however, is legendary in its toxic potency.

Alternative Lixiviants to Cyanide for Leaching Gold Ores ...

Jan 01, 2016  Initial bisulfide-leaching tests using the YES process attained 25–31% gold extraction from a bio-oxidized Nevada ore compared with 88% by conventional cyanide leaching (Hunter et al., 1998). At the same time, 39–81% silver was recovered compared to 86% with cyanide.

KINETICS OF GOLD LEACHING IN ALKALINE SULFIDE

(2 M sulfide) could not leach gold/silver. The authors observed lower gold leaching rate when using bisulfide compared to sulfide. Thus, the leaching of gold by sulfur-sulfide solution at OCP is ...

Leaching and recovery of gold from ore in cyanide-free ...

Leaching and recovery of gold from ore in cyanide-free glycine media Pelin Altinkayaa,b, Zulin Wangb, Ivan Koroleva,b, Joseph Hamuyunia, ... thiocyanate, and bisulfide have to be less toxic, in-expensive, and with high process efficiency in order to challenge cyanide in industrial gold production (Marsden and House, 2006; Muir

DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

Bisulfide Iodide Ammonia Bromide Hypochlorite Fig. 1. Potential-pH diagram showing typical operating windows for gold lixiviants (after Aylmore, 2005) In leaching of gold a complexing ligand and oxidant are needed. Dissolution of gold in cyanide solution is shown in Eq. 1. At low cyanide concentrations, the dissolution rate is a function of ...

(PDF) Alkaline Sulfide Recovery Of Gold Utilizing Nitrogen ...

stable complex with gold than bisulfide as shown by the larger stability constant, confirming ... some insights into the mechanism of gold leaching in alkaline sulfur-containing solutions were ...

Bisulfide - an overview ScienceDirect Topics

In lower-temperature aqueous fluids, gold behaves as a soft (i.e., large and deformable) metal ion, bonding covalently with the soft bisulfide ligand (Wood et al., 1987), whereas at temperatures greater than ∼350–400 °C, chloride complexes become important. This effect is probably due to the increasingly ionic nature of bonding within ...

(PDF) Alkaline Sulfide Gold Leaching Kinetics

Recently, leaching of gold with cyanide has come under scrutiny for its possible detrimental effects to the environment. Also, in some gold bearing ores and concentrates, conventional cyanide ...

Sulfide/Bisulfide/Sulfite Leaching Sulfur Sulfide

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Fundamentals and applications of alkaline sulfide leaching ...

Gold lixiviation is the result of leaching by polysulfide oxidation and sulfide complexation, as shown in Equation 8 (Anderson, 2001a;Anderson et al., 2004 Anderson et al., , 2005 Jeffrey ...

Biocatalyzed leaching of precious metal values - HUNTER ...

At a gold concentration of 10 mg/l, all of the gold in a ton of low grade (0.05 oz/ton) ore can be complexed in 140 liters of bisulfide leach solution. In a preferred embodiment, the anaerobic reactor and the leaching reactor are operated together as a single, essentially completely-mixed reactor.

(PDF) ALKALINE SULFIDE RECOVERY OF GOLD UTILIZING

Alkaline Sulfide Gold Leaching with Electrowinning Recovery = 93.1 % Table XVII.-Summary of Site Specific Economics for NSC Partial Oxidation of a Gold Bearing Chalcopyrite Ore NSC Chalcopyrite Ore Partial Oxidation Cost = $ 3,500,000.00 USD NSC Chalcopyrite Partial Oxidation Operating Cost = $0.056 USD/lb Cu or $ 0.36 USD/g Au Chalcopyrite ore ...

Thiosulfate - an overview ScienceDirect Topics

Bisulfide leaching can be utilized in a number of cases, such as refractory sulfides, lean-grade carbonaceous gold–silver containing ores, and regular lean-grade oxidized ores. A combined chemical and biological heap leaching of an oxide gold-bearing ore containing 3.5 g/ton of gold and 14.0 g/ton silver has been reported.

Bioextraction Mechanisms of Metals From Their Ores

Gold is dissolved in this bisulfide solution and recovered with activated charcoal or zinc dust. The described process of gold leaching is in fact natural sulfur cycle and it has been postulated that sulfur cycle is absolute solution to the recovery of this precious metal.

KINETICS OF GOLD LEACHING IN ALKALINE SULFIDE

(2 M sulfide) could not leach gold/silver. The authors observed lower gold leaching rate when using bisulfide compared to sulfide. Thus, the leaching of gold by sulfur-sulfide solution at OCP is ...

Alternative lixiviants to cyanide for leaching gold ores ...

Hunter et al. (1998) noted a variety of environmental advantages of bisulfide leaching, such as, reusable acidic sulfate wastes to produce bisulfide lixiviant, no residual toxins (cyanide) or ...

DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

Bisulfide Iodide Ammonia Bromide Hypochlorite Fig. 1. Potential-pH diagram showing typical operating windows for gold lixiviants (after Aylmore, 2005) In leaching of gold a complexing ligand and oxidant are needed. Dissolution of gold in cyanide solution is shown in Eq. 1. At low cyanide concentrations, the dissolution rate is a function of ...

Method and apparatus for extracting precious metals from ...

For gold and/or silver leaching, information on the aqueous chemistry of gold and silver bisulfide complexes and other chemical species likely to be present in a bisulfide lixiviant is used (see Barnes, H. L. (ed.), Geochemistry of Hydrothermal Ore Deposits, 2nd ed.,

Sulfide/Bisulfide/Sulfite Leaching Sulfur Sulfide

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The leaching and adsorption behaviour of gold ores

4.4 the effect of copper cyanide on gold leaching from oxide and sulphide ores 110 4.5 summary 114 chapters preg-robbing phenomena in the cyanidation of gold ores 116 5.1 objectives of this chapter 116 5.2 background information 116 5.3 preg-robbing behaviour by the ores at low cyanide ...

Gold Metallurgy and Leaching Process

Leaching, often gold, is the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy, of gold, it is the process of dissolving a certain mineral (or minerals) from an ore or a concentrate, or dissolving certain constituents from materials such as a calcines, mattes, scrap alloys, anodic slimes, etc., to achieve either one or two purposes ...

The cyanide leaching of gold in solutions containing ...

Sep 01, 2000  RESULTS AND DISCUSSION Kinetic aspects of gold leaching in solutions containing hydrosulfide ions The REQCM was used to study the leaching of gold in air saturated 5 mM cyanide solutions in the presence and absence of hydrosulfide ions. Shown in Figure 1 are the kinetic plots, which show the change in mass as a function of time.

The Metallurgy of Cyanide Gold Leaching – An Introduction ...

Oct 20, 2014  Nature of Gold: The surface of a gold particle will typically be dissolved at a rate of around 0.2-0.5 µm 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.

Sodium Meta Bisulfite VS Sodium pyro sulfite - Gold ...

Oct 19, 2012  not sure if you mis-spelled sodium Bisulfite or you meant to type disulfite (which im not sure, well im pretty sure thats not even a compound) . sodium bisulfite will work to precipitate gold. sodium metabisulfite is recommended because it was very easy to source not so long ago. you could buy it at the grocery store and where ever canning ...

Method for thiosulfate leaching of precious metal ...

The gold extraction peaked at approximately 83%, the maximum extractable, after 6 hours leaching. Gold leaching was slowed if the temperature was lowered to 40° C., but 80% gold extraction was still obtained after 10 hours leaching at 40° C. An overall summary of the results is provided below:

CA2409378A1 - Method for thiosulfate leaching of precious ...

CA2409378A1 CA002409378A CA2409378A CA2409378A1 CA 2409378 A1 CA2409378 A1 CA 2409378A1 CA 002409378 A CA002409378 A CA 002409378A CA 2409378 A CA2409378 A CA 2409378A CA 2409378 A1 CA2409378 A1 CA 2409378A1 Authority CA Canada Prior art keywords precious metal thiosulfate leach solution contacting pregnant Prior art date 2000-05-19 Legal status

Aqua Regia Process Gold Extraction from aqua regia

Sep 24, 2017  Gold Testing: Gold testing is the main part of aqua regia process. Now, the question is this, How to check gold in solution. You can use stannous chloride for the gold test. Simply take a pinch of stannous chloride and dissolve in water. Take a drop of gold solution on filter paper piece and use stannous chloride solution on it.

Solution mining of precious metals using aqueous, sulfur ...

Present evidence suggests that gold concentrations track more closely with polysulfide species than they do with thiosulfate of bisulfide species. For example, if gold-thiosulfate and gold-bisulfide species were the dominant complexing agent for the gold, one would have expected dissolved gold concentrations of be similar for Au-S-6 and Au-S-16.