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Gold Ore Processing: Project Development and Operations, Second Edition, brings together all the technical aspects relevant to modern gold ore processing, offering a practical perspective that is vital to the successful and responsible development, operation, and closure of any gold ore processing operation.This completely updated edition features coverage of established, newly implemented ...
Oct 20, 2014· Preg-robbing 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.
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 (preg-robbing) and this resulted in gold losses and low recovery when processing these ore types.
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 ...
Trace amounts of gold with a mixture of illite/smectite clay, montmorillonite and free carbon were observed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry, indicating potential for preg-robbing by clays and carbon. Preg-robbing is a process that prevents some of the gold from being recovered, making extraction less effective.
Measuring Potential in a Pressure Oxidation Autoclave II (Barrick Gold Corporation, NSERC Collaborative Research and Development Grant; US Patent Application: 62/500,358). ... Preg-robbing in Gold ...
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.
Western University Scholarship@Western Electronic Thesis and Dissertation Repository May 2018 Study on the surface features of Preg-Robbing carbonaceous matter during oxidation treatment
These ores contain organic/inorganic carbon, silicates and sulphide minerals, which are known to have potential for preg-robbing of gold from cyanide solutions. However, these ores showed no discernable preg-robbing behaviour and hence, the refractory behaviour of these ores could not be attributed to the preg-robbing phenomenon.
Mar 19, 2009· A new gold bearing sulfide ore (BR31 new) is ground to P 80 less than 70 microns. The POX-CIL 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 preg-robbing TCM is concentrated, as shown in FIGS. 1A and 1B.
The gold deportment data show that 37.5% of the gold losses in the CIL residue are related to sub-microscopic gold contained in the unoxidized pyrite mineral phase (Figure 1). The carbonaceous matter present in the ore exhibits strong preg-robbing capacity and contributes to 44.5% of the gold losses in the form of surface gold (Figure 1).
US5536297A . 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 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:
The Use of Mercury to Inhibit Autoclave Preg-Robbing of Gold: Pilot Plant Trials ... Practical Treatment Options for Carbonaceous Preg-Robbing 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 preg-robbing or, in other words, to the re-sorption or solution depletion.
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 preg-robbing due to the presence of organic carbon. These must be pretreated ahead of leaching.
At Lone Tree, nitrogen gas flotation is used to minimize oxidation of arsenian pyrite during flotation. Straight cyanidation of gold-bearing pyrite usually results in poor recoveries so a pre-cyanide oxidation step is used. Roasting and high-temperature, high-pressure oxidation in an autoclave are the two two main methods used.
method to improve recovery of gold from double refractory gold ores Publication number: 20090071295 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.
DLT serves to qualitatively evaluate the gold occurrences within the ore. Preg-robbing, or the ore's capacity to fix dissolved gold, is evaluated to determine physical surface interactions (preg ...
Organic carbon present in gold ore may adsorb dissolved gold-cyanide complexes in much the same way as activated carbon. This so-called "preg-robbing" carbon is washed away because it is significantly finer than the carbon recovery screens typically used to recover activated carbon. Pre-treatment options for refractory ores include: Roasting
"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%.
This is done by autoclave pressure oxidation (AC POX), a technology commonly used in the mining industry for ores with a high refractory gold content. Gold ores commonly contain active carbonaceous materials which have the ability to adsorb, or preg-rob, gold during the AC POX and/or cyanidation steps of the recovery process, and gold losses ...
to commonly as "preg-robbing". 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 ...
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 preg-rob capacity due to limited oxidation effect on CMs (Simmons, 1995).
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