reg robbing gold in autoclave o idation

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Sulfide sulfur oxidation through the autoclave is typically of the order of 90—92%. Residual S exiting the autoclave is targeted at less than 0.2%. Values greater than 0.25% S" typically result in poorer gold recoveries in the C1L circuit. Free-acid levels in the autoclave discharge are a function of S2 and CO2- in the autoclave feed, but ...

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A process for recovering gold in which an ore slurry of refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon is subjected to pressure oxidation in an autoclave. The oxidized ore slurry is mixed with a thiosulfate salt lixiviant, which mixture is maintained at a pH between 7 and 8.7 while the slurry is agitated in a ...

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Colloidal gold is the principal form in which gold is encountered in the Goldstrike ores, especially the refractory-sulphide category. The majority of the gold--up to 75%--is accounted for in pyrite and marcasite. Gold concentration in the iron sulphide increases with decreasing sulphide grain size.

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"Pressure oxidation was selected as the most feasible processing technology for double refractory ores. It is able to achieve gold recoveries of 96% by utilising high temperatures, elevated pressure and oxygen to recover encapsulated gold, while conventional cyanidation methods would result in sub-optimal recovery rates of 20-40%.

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Freeport McMoRan Inc. - The Evolution of Pressure Oxidation at Freeport-McMoRan: The Past, Present, and Future. Donlin Gold LLC. - Implementation of Autoclaves in the Donlin Gold Flowsheet 9:20 9:45 Goldcorp Inc. - Red Lake Gold Mines Design and Operation Evolution +25yrs EcoMetales Ltd. - PLCC Project - Autoclave Technology

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A process for treatment of precious metal ores in which gold is leached from an oxidized ore slurry using a thiosulfate salt lixiviant and copper catalyst. Gold and copper are subsequently loaded onto an ion exchange resin. Copper is recovered from the resin by elution with a thiosulfate solution; gold is recovered from the resin by elution with a thiocyanate colution.

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 · With lower gold grades beneficiation (usually flotation) is often used ahead of leaching to increase the grade of Au and reduce the quantity of ore to be leached. 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 ...

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The authors of this study have recently applied pressure leaching with iodide to refractory gold ores, a technique developed as a noncyanide process for refractory gold ores. This new process is a one stage operation, where the oxidation of sulfide and the dissolution of gold are completed in an autoclave …

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Flowsheet development for Agnico Eagle's refractory gold Kittila project in Finland. ... which passivated gold during the autoclave oxidation. Arsenic is situated in a stable nontoxic form of iron ...

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Pressure oxidation allows to carry out the efficient processing of goldbearing sulfide materials. However, application of this method for processing of double refractory raw materials leads to irreversible gold losses due to autoclave preg-robbing of gold by organic carbon. Thermodynamic and experimental data indicate that almost complete sulfide decomposition leads to a high value of ...

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Alacer Gold Corp. (OTCPK:ALIAF) Q1 2019 Earnings Conference Call April 30, 2019 5:00 PM ET Company Participants Lisa Maestas - Director of Investor Relations Rod Antal - President & Chief ...

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Treatment of Refractory Gold Ores Extractive Metallurgy Once the cause has been identified, there are a number of alternatives for treating the ore. Firstly, the gold can be made more amenable to cyanidation by ultra-fine milling, followed by a hot atmospheric leach –the Albion Process.

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Gold extraction refers to the processes required to extract gold from its ores.This may require a combination of comminution, mineral processing, hydrometallurgical, and pyrometallurgical processes to be performed on the ore.. Gold mining from alluvium ores was once achieved by techniques associated with placer mining such as simple gold panning and sluicing, resulting in direct recovery of ...

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Nevertheless, the pressure oxidation of double refractory materials containing carbonaceous matter in addition to sulfides results in substantial gold losses due to autoclave preg-robbing.

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Preg-robbing is an important phenomenon that inhibits gold recovery due to the presence of naturally occurring carbonaceous matter. In case of certain ores, gold recovery by cyanidation is limited by the presence of naturally occurring carbonaceous material that adsorbs gold from alkaline cyanide solution unless steps are taken to prevent this adsorption reaction from occurring.

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CIP and CIL Carbon-in-pulp (CIP) is the sequential leach then absorption of gold from ore. During the CIP stage, pulp flows through several agitated tanks where sodium cyanide and oxygen have been added to dissolve gold into solution.

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Gold recovery can be adversely affected by preg‐robbing on inherent carbonaceous material during autoclave pressure oxidation of sulphide ores. The time of flight (TOF) SIMS (TOF‐SIMS) technique has been applied for direct determination of gold species on individual carbonaceous particulates from AC POX stream samples.

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The Macraes Process Plant recovers gold by concentrating the metal into a relatively small fraction of flotation concentrate, oxidising the reground concentrate in a pressure oxidation autoclave, washing the oxidised residue and then utilising a carbon-in-leach process to recover gold from the residue. In detail the plant comprises:

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"Pressure oxidation was selected as the most feasible processing technology for double refractory ores. It is able to achieve gold recoveries of 96% by utilising high temperatures, elevated pressure and oxygen to recover encapsulated gold, while conventional cyanidation methods would result in sub-optimal recovery rates of 20-40%.

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Method of gold recovery from sulfide auriferous ores has already been proposed (Smolyaninov et al. 2010b). The invention relates to the method of gold recovery from powdered sulfide auriferous ores after their unlocking by bacterial leaching or by oxidation roasting, or by autoclave oxidation.

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Autoclave design is driven by various safety standards, foremost among which is the ASME Pressure Vessel Code. While most nations use the ASME code, some have developed their own. The CE standard in Europe applies to vessels as well as to electrical controls, and China requires that pressure vessels comply with their domestic code.

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Barrick Gold Corporation. ... Autoclave treatment of refractory sulfide gold ores oxidizes minerals, such as pyrite, containing gold that cannot be recovered through conventional cyanidation. Oxidation liberates the gold by putting iron into solution. At high temperature and …

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Feed, mill and autoclave products were studied at different stages of an autoclave process to identify the reason for variable recovery in some ores. Under the standard operating conditions of the autoclave mill, there is a high recovery of gold, which occurs predominately as chemically included gold within arsenian (arsenic-containing) pyrite.

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Pressure oxidation of pyrite-arsenopyrite refractory gold concentrate 103 Autoclave oxidation tests were conducted in Büchi ecoclave model 075 titanium autoclave. The total volume of the autoclave vessel was about 1.1 dm3 and it was equipped with magnetic …

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A double refractory gold ore contains gold particles locked in sulphides, solid-solution in arsenopyrite, and preg-robbing material such as carbonaceous matter, and so on. The diagnostic leach test (DLT) and preg-robbing (PR) approaches are widely used to investigate the occurrence and the distribution of refractory gold. DLT serves to qualitatively evaluate the gold occurrences within the ore.

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the carbonaceous, preg-robbing ores of Barrick's Goldstrike orebody in the Carlin Trend of Nevada, USA. These ores have proven to be amenable to thiosulphate leaching, under mild conditions; gold leaches rapidly as the gold thiosulphate complex, which, because of its low affinity for graphitic carbon, does not suffer the preg-robbing

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 · Thiosulfate generation in situ in precious metal recovery ... subjecting the pyritic ore slurry to partial oxidation by pressure oxidation in an autoclave for a residence time between about 30 and about 180 minutes at a temperature between about 100° C. and about 185° C. whereby between about 2 and about 35% of sulfide in the ore is converted ...

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Merrill-Crowe zinc process) followed by an elution process that strips the gold cyanide complex from the carbon and electrowinning to plate the gold onto cathodes. The gold is then smelted and refined to obtain a finished product. Many of the world's remaining gold resources, however, are not readily amenable to conventional 2cyanidation.

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The second occurs when graphite or carbonaceous matter is present. In this case, the gold leaches well into the cyanide solution but then the carbonaceous minerals reabsorb the gold back into the pulp. This is known as "preg-robbing". SGS experts will identify the best solution for your ore as there are many methods to choose from:

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refractory gold minerals; locking of submicroscopic gold in sulfide and sulfarsenide mineral structures. Gold process mineralogy address all issues related to gold ore processing by the detailed study of an ore or a mill product. The methodology is widely used as a …

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