· Th e gold leaching reaction by thiosulfate without additives is shown in Eq. (4). 4Au + 8S 2 O 3 2-+ O 2 + 2H 2 O → by the combination of sodium hydroxide and elemental sulfur (Jeffrey and
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· After the leach cell is harvested, the irrigation system shall be installed and leaching will start with a cyanide solution of 50 ppm CN at an irrigation ratio of 10 L/h-m2 for a period of 60 days. The pregnant
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:Cyanide Leaching of Gold EquationGold CyanidationCyanide in Gold Processing · However, the difficult recovery of gold ions in gold leaching solutions limits further application of thiosulfate gold leaching technology. This study
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· The gold leaching efficiency was only 14% before pretreatment and the highest gold leaching efficiency after pretreatment reached 86.9%. In this study, a new method was proposed for the oxidation pretreatment of refractory gold ores, proposed a potential application for improving gold leaching performance.
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· Gold is mainly extracted from its ores or concentrates by leaching with oxygenated cyanide solutions [1,2].Cyanide consumption during leaching, and the discharge of excess cyanide in wastewater,
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:Gold Chloride in NaturePublish Year:2008In this review, the basic theory and process development of some main gold leaching systems based on thiosulfate solutions were systematically summarized to illustrate the
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· Based on the results of gold extraction at different temperature (Fig. 5 a), the leaching kinetics of gold ore in copper-citrate-thiosulfate solutions is a parabolic leaching process. Considering the fact that the change in agitation speed does not significantly affect the leaching kinetics ( Fig. 4 ), it is reasonable to assume that the
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· As a result of the comparison, it was stated that the leaching kinetics of Jin Chan chemical was slower than NaCN. While the 97% gold recovery of the solvent was in 48 h of leaching time with Jin
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· Another method that is also used to separate gold from ore in industry and small-scale gold mining is the cyanide leaching method [7, 8].Gold extraction from the rock is generally carried out
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· Cyanide-free mild chloride leaching was investigated. •. Gold could be recovered even at <520 mV vs. Ag/AgCl in carbon-in-chloride-leach mode. •. Copper was a stronger oxidant than iron in gold leaching. •. Gold was oxidized by in-situ dissolving impurities. •. Seawater contains enough chlorides to dissolve gold.
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Some sedimentary minerals have attractive contents of gold and silver, like a sedimentary exhalative ore available in the eastern of Hidalgo in Mexico. The gold and silver contained represent an interesting opportunity for processing by non-toxic and aggressive leaching reagents like thiosulfate. The preliminary kinetic study indicated that the leaching
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:Bin Xu, Wenhao Kong, Qian Li, Yongbin Yang, Tao Jiang, Xiaoliang LiuPublish Year:2017 · Thiosulfate is the most promising non-cyanide leaching reagent and the only reagent which found industrial application on gold recovery from a highly carbonaceous preg-robbing gold
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· The remaining 20% is used to manufacture sodium. cyanide, a solid form of cyanide, of which 90% (i.e. 18% of total production) is used in. mining operations around the world for gold recovery
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· Optimisation of the Leaching Parameters of a. Gold Ore in Sodium Cyanide Solution. 1* Nkosikhona Hlabangana, 2Siboniwe Bhebhe, 3Nonhlanhla G. Mguni, 4 Gwiranai Danha, 5 Joel Tshuma. *1, 2, 3, 5
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:Publish Year:2020The electrochemical-catalytic mechanism of thiosulfate leaching of gold foil is described in Figure 1. In anodic areas, NH 3 moves to the gold surface and complexes with Au + to generate the complex [Au (NH 3)
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· In a leaching solution containing 1 g/L NaCl, 1 % HCl and 2 % NaOCl, nearly 90 % of the gold was extracted in only 30 minutes. Additions of hydrochloric acid will reduce the sodium hypochlorite requirement A leach solution containing 1 g/L NaCl, 5 % HCl and 1 % NaOCl achieved nearly the same per cent gold extraction under the same
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· including calcium, sodium, and ammonium, on the leaching of a pyrite concentrat e has been studied by Feng and Van Gold Leaching from Sulfide Gold Ores/Concentrates. China Patent 201510223325.
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· Introduction to Gold and Silver Leaching. The cyanide leaching process is the most important method ever developed for extracting gold from its ores. The early development of the process is attributed to a Scotchman, John Stewart Mac Arthur, in collaboration with the Forrest brothers. The method was introduced into South Africa in
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· Eh-pH diagram for the Fe-S-CO 3 -H 2 O system at 25 °C. Another function of carbonate in OPASL is the buffering effect on the pH value. The recent study has shown that high alkalinity (pH > 12) is beneficial to the oxidation of sulfide ore, and low alkalinity (pH < 10) could promote the gold leaching by thiosulfate.
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· Leaching, often gold, is the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy , of gold, it is the process of dissolving a certain mineral (or minerals) from an ore or a concentrate, or dissolving certain constituents from materials such as a calcines, mattes, scrap alloys, anodic slimes, etc.,
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ADVANCES IN GOLD AND SILVER PROCESSING. species stable in the region of pH below 2. The amount of hydrochloric acid required to maintain a pH below 2 depends upon the concentration of hypochlorite in solution. Equation (1) shows that sodium hydroxide is produced when gold is reacted with sodium hypochlorite.
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Dissolution of elemental sulfur in sodium hydroxide can also used as a lixiviant for alkaline sulfide leaching of antimony (Anderson and Krys, 1993). The combination of sodium hydroxide and elemental sulfur results in the formation of metastable species other than just sulfide (S2−). Both polysulfide (SX 2–) and thiosulfate (S2O32–) are
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· Recently, copper-citrate-thiosulfate leaching was tested on refractory gold ore, exhibiting a similar extraction capability for gold, in which the predominant gold species is Au (S 2 O 3) 2 3 − rather than Au (N H 3) 2 + (Wang et al., 2019).
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· was assessed using leaching conditions of 24 g/L thiourea, 0.6% iron (III), pH of 1.00 at 25 °C for a period of two hours. They reported that samples of < 149 µm resulted in around. 90% gold
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:D. Feng, J.S.J. van DeventerPublish Year:2011 · In the most recent study (Baghalha, 2007), it was found that the leaching of gold from an ore has to be properly controlled to achieve high gold recovery and
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· Most of the gold in the roasting slag is recovered by thiourea/cyanide leaching process, however, the leaching residues (gold tailings) obtained from thiourea leaching process or the sodium cyanide leaching still contain 9–16 g/t gold, which is difficult to recover).
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Sodium hypophosphite (NaPO 2 H 2, also known as sodium phosphinate) is the sodium salt of hypophosphorous acid and is often encountered as the monohydrate, NaPO 2 H 2 ·H 2 O. It is a solid at room temperature, appearing as odorless white crystals. It is soluble in water, and easily absorbs moisture from the air.
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· Thiourea leaching of gold, despite first being reported in 1941 [], has never been clearly established into industry.Only a few industrial applications were reported between 1984 and 1992 [] although more recently, Birloaga et al.[] report on the development of a pilot plant.] report on the development of a pilot plant.
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After the leaching process is complete, the soluble gold must be concentrated and separated from the process slurry. The method of recovery of gold from the process slurry is by carbon adsorption. Adsorption is a term used to describe the attraction of a mineral compound to the surface of another material.
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· In order to explore the influence of sodium persulfate concentration on gold leaching, gold leaching experiments were carried out under the following conditions: 0.01–0.04 mol L −1 Na 2 S 2 O 8, 0.10 mol L −1 KI, a stirring speed of 200 rpm, a temperature of 30
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