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"In refractory ores, small particles of gold are covered by insoluble sulfides impeding the contact between cyanide and gold. In this case, a pretreatment stage must be considered, such as pressure oxidation, chemical oxidation, roasting or bio-oxidation, the latter currently being the .
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Improved gold and silver extraction from a refractory . 1 Introduction The efficiency of gold extraction from sulphidic refractory ores e g arsenopyrite FeAsS and pyrite FeS 2 by direct cyanidation is usually very low Badri and Zamankhan 2013 Faraz et al 2014 since fine gold particles in these ores are mostly locked up in the bulk and therefore inaccessible to leaching agents and dissolved ...
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Valves for gold autoclave pressure oxidation . Autoclave pressure oxidation (POX) is an effective pre-treatment option when extracting gold from refractory ore bodies, such as pyrite and arsenopyrite. While gold processing plants are the most common utilizers of .
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Apr 27, 2007· However, pretreatment processes involving thermal oxidation, such as roasting, chemical oxidation, such as acid leaching, acid or alkaline pressure leaching; or biological oxidation such as bioleaching with T. Ferrooxidans liberates gold from refractory minerals. Gold is then recovered from the oxidized mass by alkaline cyanidation.
Refractory gold and silver ores yield low gold and silver extractions in cyanide leaching [1]. A suitable pre-treatment process such as roasting [2], pressure oxidation [3], bio-oxidation [4], alkaline [5,6] or alkaline sulfide leaching [7] and, to a limited extent, ultrafine grinding [8−10], is .
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The chemistry of gold dissolution in alkaline cyanide solution has continually ... Figure 8 Effect of cyanide concentration on leaching. Pre-leaching: pH 11.2, 8 ppm O 2, 100 g/t Pb(NO 3) ... on sulfide oxidation in the absence and presence of cyanide (20.4 mM NaCN, 10 mM S2-, oxygen sparged)..... 43 Figure 19 Effect of oxygen and lead nitrate ...
alkaline pre oxidation gold cyanidation refractory Equipos de Trituración Para la producción de agregados de construcción, GMC puede ofrecer tales máquinas trituradoras de núcleos como trituradora de mandíbula, trituradora de impacto, trituradora de cono y máquina de fabricación de arena.
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OXIDATION OF REFRACTORY GOLD CONCENTRATES AND SIMULTANEOUS. Jan 01, 2004· The oxidation of refractory gold concentrates containing arsenopyrite and pyrite and the simultaneous dissolution of gold in aerated alkaline solutions at ambient temperatures and pressures without the addition of cyanide has been studied.
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Hard rock gold deposits can be further classified into three sub classes: free milling, sulfide associated and refractory. Free-Milling Gold. Gold ore is considered free-milling when over 90% of the gold can be recovered by a conventional gravity-cyanidation process with low reagent consumptions at a grind size of 80% passing 75 µm.
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Pretreatment Process on Refractory Gold Ores with As. BACTERIAL LEACHING AS A PRE-TREATMENT STEP FOR GOLD RECOVERY FROM REFRACTORY ORES In this article, pre-treatment such as bio-leaching before cyanidation is discussed as an alternative technique to treat refractory gold ores containing pyrite and arsenopyrite. There are two methods of
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Many of these ores are refractory to varying degrees and require treatment by roasting, bacterial oxidation or finer milling.Gold Balance: Submicroscopic Gold Quantificationrefractory and free-milling gold in a sample, a sequence of separations and analyses are performed to provide a complete overview of the mass balance of gold in the sample.
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The results of alkaline pre-oxidation and gold leaching by cyanidation suggested that the alkaline pre-oxidation was an effective treatment for the refractory gold ore. Gold extraction after pre-oxidation under appropriate condi- tions increased from 20% of direct cyanide leaching to 70.0%.
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The influence of pulp density, ferric ion concentration and particle size on the tank bioleaching of two kinds of refractory gold concentrates are discussed. The chemistry and mechanism of the bioleaching process are also presented. The relationship between oxidation of sulphides, liberation of enclosed gold and gold cyanidation are discussed. The consumption of NaCN could...
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1. Introduction. Gold ores are considered refractory if gold extractions from a conventional cyanidation process are less than 80% even after fine grinding. 1) Arsenic-bearing refractory gold ore has stones extremely difficult to deal with. In the stones, gold is locked up in arsenic mineral matrix as the form of microscopic or submicroscopic lattice.
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Bacteria biooxidation is an oxidation process caused by microbes where the valuable metal remains (but becomes enriched) in the solid phase. In this process, the metal remains in the solid phase and the liquid can be discarded. Bacterial oxidation is a biohydrometallurgical process developed for pre-cyanidation treatment of refractory gold ores or concentrates.
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A gold recovery pretreatment process is disclosed in which the gold content is more completely extracted from refractory sulfidic ores which contain large quantities of metal carbonates such as dolomite than occurs in traditional gold extraction methods. The process includes treating the ore in an autoclave at elevated temperature and oxygen overpressure conditions in the presence of soda ash ...
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Gold recovered during Stage 1 is not considered refractory. A portion of the cyanidation leach residue is advanced to Stage 2. Stage 2: Leach residue is reacted with hydrochloric acid to dissolve labile sulfide minerals such as pyrrhotite and liberate any gold that may be associated with them. The residue is then subjected to cyanidation and a ...
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of refractory gold. Statistics show that, in the world, about 2/3 gold resource belongs to the difficult processing ores, and about 1/3 total output of world gold is produced from refractory gold. This proportion will further increase in future. Therefore, pre-treatment of arsenic-bearing refractory gold has an extreme-ly important significance.
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Cyanide leaching is the standard method used for recovering most of the gold throughout the world today. The process originated around 1890 and quickly replaced all competing technologies. The reason was strictly economical in nature. Where amalgamation plants could recover about 60% of the gold present, cyanide could recover about 90%.
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The process options for oxygen consuming ores are thus to use alkaline pre-oxidation, or aeration and flotation, followed by a cyanide leach with oxygen addition. Preg-Robbing Complex Ores. Preg-robbing occurs when a gold cyanide complex is removed from solution by some component of the ore.
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The extraction of silver and gold tended to improve with increasing the concentration of Na 2 S at fixed concentrations of NaOH . It can be inferred from these findings that alkaline sulphide pretreatment renders the gold and silver-bearing refractory phases amenable to cyanide leaching. Download : Download full-size image; Fig. 6.
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The results of alkaline pre-oxidation and gold leaching by cyanidation suggested that the alkaline pre-oxidation was an effective treatment for the refractory gold ore. Gold extraction after pre-oxidation under appropriate condi- tions increased from 20% of direct cyanide leaching to 70.0%.
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The process options for oxygen consuming ores are thus to use alkaline pre-oxidation, or aeration and flotation, followed by a cyanide leach with oxygen addition. Preg-Robbing Complex Ores. Preg-robbing occurs when a gold cyanide complex is removed from solution by some component of the ore.
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Cyanide leaching is the standard method used for recovering most of the gold throughout the world today. The process originated around 1890 and quickly replaced all competing technologies. The reason was strictly economical in nature. Where amalgamation plants could recover about 60% of the gold present, cyanide could recover about 90%.
technology with the addition of a simple pre-oxidation stage(3 agitated tanks) prior to the CIL circuit to account for the refractory gold telluridecomponent in the mineralisation. Cyanide consumption was low at 0.26kg/t, whilst lime requirements were slightly higher than average at 1.93kg/t.
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• Pretreatment of refractory gold ore: Bacterial oxidation Pressure oxidation Roasting Emerging technologies: thiosulphate leaching, resin-in-pulp, Augment, the Albion process, Activox and others. • Leaching: Conventional cyanidation, 1) Using agitated pachuca tanks 3 or high-efficiency
Get PriceApr 01, 1996· The pretreatment of these so-called refractory ores is most usually aimed at releasing gold encapsulated in sulphide particles (the most common matrix for refractory gold being pyrite with or without arsenopyrite), either physically by grinding, or chemically by oxidation of the sulphide minerals.
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Refractory gold ore pretreatment Treatment of refractory gold ore (whole ore and flotation concentrates) has become more prominent since the 1980s, with many gold discoveries often including ores that are wholly or partially refractory. Refractory pre-treatment processes include pressure oxidation, biological oxidation and various forms of ...
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However, refractory gold ores are often characterized by the low gold extractions (<50 80%) in cyanide leaching The refractoriness of gold ores and concentrates stems primarily from the inherent mmeralogical features with reference to the mode of presence and association of gold, and carbonaceous matter present In practice, the refractoriness has
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Precious metals such as gold can be extracted from a refractory ore using a conventional cyanide leaching step and with reduced cyanide consumption by pre-treating the ore prior to cyanide leaching. The refractory ore is pretreated by fine grinding and an initial leaching step which uses inexpensive limestone and lime to maintain the initial leach relatively alkaline.
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cyanidation of a pyrrhotite bearing gold ore cyanidation of a pyrrhotite bearing gold ore The most of refractory ore is gold bearing sulfideto complete alkaline pre oxidation for pyrrhotite so makes gold easier to cyanide and leach The Recovery Of Gold from its (PDF) Cyanidation of a pyrrhotite bearing gold .
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Gold Sulphide Ore Oxidation by Alkaline Pressure. ... the selective and bulk flotation methods are considered as primary sulphidic refractory gold ore pre-treating options. ... contain both pyrite and carbonaceous matter and the latter results in the loss of gold from solution during cyanide leaching.
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The problem of refractory sulfide gold ore that has a gold recovery less than 50% when direct cyanidation applied, still exists until now. It needs oxidative pretreatment for cyanidation to be effective in gold recovery the objective of this study is figuring out the effect of sodium nitrite as an oxidizing reagent on cyanidation of refractory gold ore.
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