2.1 Microwave pre- treatment of refractory gold ores . Most of refractory gold occurs within sulphide minerals such as FeS 2 and FeAsS and are treated by roasting, pressure leaching or bacterial leaching to render the gold amenable to recovery …
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A comprehensive description of roasting practice is to be found in a series of articles entitled "Roasting Gold-Silver Sulphide Ores and Concentrates" by M. W. von Bernewitz. A more recent paper, " Roasting of Arsenical Gold Ores and Concentrates" by F. R. Archibald contains a bibliography listing 23 references on the subject of ...
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The preg-robbing of the sulphide ores could not solely be the result of a deficit of free cyanide, or preg-robbing would have been observed for the oxide ores. The Au(CN) 2 − complex was found to be stable in the oxide ore slurries.
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CuSO 4 solution can also be used for removing Pb, Zn, and Fe from copper sulphide ores. In presence of oxidizing agents: Ferric ion: Ferric sulphate or chloride react with metal sulphides liberating elemental sulphur, e.g. Zns + 2Fe 3 + ^ Zn 2 + 2Fe 2 + + S And in the case of cuprous sulphide Cu 2 S + 2Fe 3 + ^ CuS + Cu 2 + + 2Fe 2 + CuS + 2Fe ...
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Gold sulfide ore forms when gold-bearing minerals crystallize within rocks. The mining process involves extracting these ores, usually from underground or open-pit mines. …
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Sulfide minerals (such as pyrite) contain one or several metallic elements and sulfur as the only nonmetallic element. Bonding is variable: generally either covalent, metallic, or a combination of both. ... Pyrite, also called fool's gold, is seen in Figure 9.31. The specimen in the photo has pyrite's typical metallic golden color. Figures ...
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In this study, we conducted experiments to characterize the effects on gold extraction of ores using a range of sodium cyanide concentrations (1–8 g/L), temperatures (40–75 °C), and oxygen ...
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The paper presents an overview of bio-oxidation of sulphidic refractory gold ores prior to gold cyanidation. This review discusses several factors, more importantly, oxygen requirements and oxygen ...
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Gold sulfide ores possess a unique chemical composition that sets them apart. Pyrite, the most abundant mineral, is an iron sulfide (FeS₂) with a hardness of 6-6.5 on the Mohs scale. Arsenopyrite, a complex sulfide of iron and arsenic (FeAsS), displays a hardness of 5.5-6. Chalcopyrite, a copper iron sulfide (CuFeS₂), falls slightly higher ...
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This increase in gold recovery suggests that the F-100 is a better gold collector than thiol reagents in mixed sulphide ores. Figure 2 shows the F-100 collector having higher gold recover than potassium amyl xanthate at a pH greater than 11. ... Liberated native gold ores Klimpel and Isherwood (1993) showed the sensitivity of the collectors S ...
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The U.S. Bureau of Mines developed an alkaline oxidative pretreatment to increase the recovery of gold from refractory sulfide ores containing arsenopyrite (FeAsS) and/or pyrite (FeS2). Pretreatment of a low grade ore containing 0.4% FeAsS, 3.5% FeS2, and 2.74g/mt Au with 1.2M NaOH, 40 psig 02, 100° C, and 4 hr in a 2-L autoclave resulted in ...
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The gold in refractory ores is often locked within sulphide minerals, or it may be present as fine particles 'invisible' to the naked eye. The presence of organic carbon, certain clays, or minerals that naturally absorb gold can also …
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Many gold deposits contain finely disseminated gold particles in iron sulfide minerals such as pyrite. These minerals are called refractory gold ores because of the presence of gold, which occurs either as disseminated fine …
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Gold in refractory ores occurs as fine-size gold-bearing sulfide minerals. In this study, the microwave-assisted roasting method has been investigated as a pretreatment for a refractory gold ore ...
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Gold ores are classified "free-milling" and "refractory" based on their response to cyanide dissolution. Bioprocessing can be used to treat refractory gold-bearing sulfide ores as well as carbonaceous gold ores. It is essential to characterize different types of gold ores to understand the extent and nature of gold-entrapment in different associated mineral phases before an …
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Recovering gold from sulfide refractory gold ore has been an important guarantee for the sustainable development of gold industry, while there are many challenges in the …
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Ores with Gold Locked in Sulphides • Roasting of whole ore or flotation concentrate to burn off the carbonaceous material and oxidize the gold bearing sulphide . • Pressure oxidation to deactivate the carbonaceous material and oxidize the gold bearing sulphide. • Rejection of carbonaceous material in flotation circuit if included. 9
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A typical example of a mixed gold ore is one having some level of free or native gold occurring with the remainder being associated with various types of sulfide minerals (Teague et al., 1999a). The selection of an optimal flotation reagent scheme is very dependent on the specific mineralogy of the gold ore to be processed (Blaskett and ...
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Gold particles in an ore deposit will vary in size from large nuggets to particles locked in the crystal lattice of sulfide minerals. These sulfide minerals are referred to as gold carrier minerals and contain trace to minor amounts of gold (Taggart, 1927, Chryssoulis and Cabri, 1990).Often it is found that gold ores are refractory due to the small size of the gold …
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Two examples are the large low-grade ore bodies which require very fine grinding and refractory sulphides which have to be concentrated and roasted to expose gold to cyanide …
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The flotation process, which is today so extensively used for the concentration of base-metal sulphide ores and is finding increased use in many other fields. In 1932 flotation plants began to be installed for the treatment of gold and silver ores as a substitute for or in conjunction with cyanidation.
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It is extremely important when treating high sulfide ores with cyanide to keep a sufficient protective base in the solution. Many sulfide minerals also contain things like copper or antimony that can react with the cyanide, preventing the cyanide from leaching out the gold and silver.
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Low-grade refractory sulphide gold ores exist in which the gold values are too low to economically justify the use of pre-concentration processes. The pre-concentration process (usually flotation) is followed by the oxidation of the sulphidic concentrate to render the gold amenable to a subsequent cyanide leach. Oxidation processes that have ...
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sulphide carbon-bearing gold ores or float concentrates extracted from them: scheme with pressure oxidation and bio-oxidation (bacterial oxidation) [4]. [5]. These schemes are applicable only for ores the gold content of which is at least 2.5 - 3 g/t. Therefore, the
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Green non-toxic extracting gold from refractory sulfide gold ore using thiosulfate is an essential guarantee for the sustainable development of the gold industry. However, there …
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Bio-oxidation of gold ores consists of the removal of sulfide minerals from cyanidation feed by oxidative dissolution catalyzed by chemolithoautotrophic bacteria . The role of the microorganisms in bio-oxidation is to oxidize sulfide minerals by utilizing ferrous iron and sulfur compounds [ 12 ].
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In comparison, graphite had a much lower coating ability on gold. The addition of free carbonaceous matter to pre-ground non-carbonaceous sulphide gold ores did not have much effect on gold cyanidation. However, the carbonaceous matter ground with the non-carbonaceous sulphide ores significantly reduced gold leaching kinetics and recoveries.
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Gold in carbonaceous sulfide ores is. usually recovered by pre-oxidation. followed by cyanidation with or without. prior concentration by flotation. Gold. recovery from the carbonaceous sulfide.
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At Cortez Gold Mines in Nevada, the first Lurgi CFB roaster for whole ore roasting has been installed for calcining 90 st/h of gold bearing refractory ore. The ore contains 1.1% sulfide sulfur, 1.1% organic carbon and …
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The findings of this study suggest that the application of pressure oxidation for refractory gold ores is environmentally more attractive for highly refractory ores due to the presumably high consumption of leaching chemicals, but there could be clear benefits in direct leaching for partially refractory sulfide ores depending on the leaching ...
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This special treatment is required for two reasons: first, to liberate gold particles encapsulated in sulfide or arsenic minerals; and, second, to eliminate carbonaceous material occurring in the ore, which adsorbs dissolved gold instead of active carbon that is normally added to the leaching solution. ... refractory ores yield costs per ounce ...
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These are ores that contain gold and other precious metals in a form that is not easily amenable to extraction by conventional leaching techniques. The gold in refractory ores is often locked within sulphide …
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In order to overcome the difficulty of extracting gold from gold-bearing sulfide ore by cyanide process, flotation was adopted based on mineralogical analysis. Mineralogy shows that gold particles are of superfine structure and mainly enclosed by sulfide ores. Primary gold-bearing sulfide ore is fine-grained pyrite and arsenopyrite. The paper describes the effects of ratios …
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Stibnite (Antimony Sulphide, Sb2S2) This mineral in an ore acts as a weak acid, combining with alkalis to form salts, of the order of M1/3SbS2 and M1/3SbS4 alkaline sulphantimonite and sulphantimonate, especially in the …
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Refractory gold evaluation testwork services. Refractory gold ores generally contain sulphide minerals, and as such, a primary flotation stage is the obvious choice to concentrate the sulphides into a smaller mass for downstream pre …
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Gold(I) Sulfide (Au2S) decomposes at 240 C. Gold(III) Sulfide (Au2S3) decomposes at a mere 200 C. ... Some of the richest mines in the US are sulphide ores that are no longer in production due to the nasty issues created in getting rid of the sulfide.
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Gold is present in refractory sulfide gold ores mainly in arsenian pyrite and arsenopyrite, where it occurs in both the chemically bonded state and as nano-size grains of metallic gold. During roasting or pressure oxidation, the sulfide matrix is destroyed and essentially all the gold is converted to the metallic form. The liberated gold is readily dissolved in conventional cyanide …
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