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The Use of Mercury to Inhibit Autoclave PregRobbing of Gold: Pilot Plant Trials ... Practical Treatment Options for Carbonaceous PregRobbing Gold Ores La Brooy Stephen 9560 ... Pressure Oxidation in Gold Circuits: Basic Ferric Arsenate Sulphate and Basic Ferric Sulphate Behaviour in .
Firstly, in auriferous ores containing an organic carbon material, the recovery of gold by thiosulfate leaching is generally significantly higher due to the insensibility of the thiosulfate complex of gold to the pregrobbing or, in other words, to the resorption or solution depletion.
ways: a) Pressure oxidation for sulphide oxidation and CM passivation; recommended grain sizes should be smaller than 25 microns and autoclave operated at the temperatures of 225°C or greater. The approach is primarily limited to processing double refractory ores with low pregrob capacity due to limited oxidation effect on CMs (Simmons, 1995).
"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 suboptimal recovery rates of 2040%.
Refractory gold ores are those that do not yield high gold recoveries in conventional cyanideleaching circuits, even when the ore is finely ground. The cause of low gold recoveries can be either through the presence of naturally occurring ''preg robbing'' carbonaceous materials or gold physically ''locked'' in sulphide minerals.
USA . A process for recovering gold in which an ore slurry of refractory sulfidic and refractory carbonaceous ore having pregrobbing characteristics due to the presence of organic carbon is subjected to pressure oxidation in an autoclave.
"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 suboptimal recovery rates of 2040%.
To complicate matters further, these ore bodies are often refractory, where the gold is locked within sulphide minerals; or double refractory, in which gold is locked within sulphide minerals and pregrobbing due to the presence of organic carbon. These must be pretreated ahead of leaching.
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 "pregrobbing". SGS experts will identify the best solution for your ore as there are many methods to choose from:
At Lone Tree, nitrogen gas flotation is used to minimize oxidation of arsenian pyrite during flotation. Straight cyanidation of goldbearing pyrite usually results in poor recoveries so a precyanide oxidation step is used. Roasting and hightemperature, highpressure oxidation in an autoclave are the two two main methods used.
ApregrobbingB wx2 . Pregrobbing occurs during ore processing when the ore sequesters gold from the pregnant cyanide solution during leaching. Carlin trend ores contain natural organic carbon that varies in pregrobbing behavior 3 . Since thewx pregrobbing nature of Carlin trend ore may prevent recovery of a significant fraction of gold ...
Pregrobbing is the name of the process where carbonaceous material in a leach absorbs gold and goldcyanide complexes so it is removed from the solution. Although pregrobbing can be a real problem for certain gold mines, the process is used to advantage in the Carbon in pulp (CIP) method for extracting gold from low concentrations. References
to commonly as "pregrobbing". The carbon added in CIL is more active than native carbon, so the gold will be preferentially adsorbed by carbon that can be recovered for stripping. The CIL process will frequently be used in small cyanide mills to reduce the complexity and cost of the circuit. There are several disadvantages to CIL compared ...
method to improve recovery of gold from double refractory gold ores Publication number: Abstract: The present invention is directed to a precious metal recovery process in which carbonaceous material, such as preg robbing carbon, is floated after sulfide oxidation to separate the carbonaceous material from the precious metal.
These ores contain organic/inorganic carbon, silicates and sulphide minerals, which are known to have potential for pregrobbing of gold from cyanide solutions. However, these ores showed no discernable pregrobbing behaviour and hence, the refractory behaviour of these ores could not be attributed to the pregrobbing phenomenon.
Oct 20, 2014· Pregrobbing material can be deactivated prior to leaching by the addition of kerosene or diesel or similar blinding agents. Cyanicides : Cyanide is an aggressive compound, and will react and be consumed by a number of mineral species other than gold – species known as cyanicides.
Determining gold balance in refractory gold ores 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 ...
PregRobbing Gold Ores. ... (Second Edition), 2016. Pressure Oxidation. This technique uses autoclave leaching with pure air/oxygen, high pressure, and temperature for the treatment of ... (Dunne et al., 2013), along with the control of free acid and sulfide sulfur oxidation extent to minimize gold loss in the autoclave associated with ...
DLT serves to qualitatively evaluate the gold occurrences within the ore. Pregrobbing, or the ore''s capacity to fix dissolved gold, is evaluated to determine physical surface interactions (preg ...
A process for recovering gold in which an ore slurry of refractory sulfidic and refractory carbonaceous ore having pregrobbing 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 while the slurry is agitated in a ...
Even after sulfide oxidation in the autoclave, during CIL, organic carbon present in the ore would compete with activated carbon for the cyanide gold complex in solution (pregrobbing) and this resulted in gold losses and low recovery when processing these ore types.
Mar 19, 2009· A new gold bearing sulfide ore (BR31 new) is ground to P 80 less than 70 microns. The POXCIL recovery was similar to that shown in Table 3. The POX discharge was treated using a two stage flotation process consisting of rougher and cleaner flotation circuits, wherein a portion of the pregrobbing TCM is concentrated, as shown in FIGS. 1A and 1B.
Organic carbon present in gold ore may adsorb dissolved goldcyanide complexes in much the same way as activated carbon. This socalled "pregrobbing" carbon is washed away because it is significantly finer than the carbon recovery screens typically used to recover activated carbon. Pretreatment options for refractory ores include: Roasting
The gold deportment data show that % of the gold losses in the CIL residue are related to submicroscopic gold contained in the unoxidized pyrite mineral phase (Figure 1). The carbonaceous matter present in the ore exhibits strong pregrobbing capacity and contributes to % of the gold losses in the form of surface gold (Figure 1).
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