The thiourea (TU) leaching of gold from refractory ores can be considered an alternative to cyanidation. However, the high reagent consumption causes an increase in cost, which seriously limits its use. In …
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The leaching of gold in thiourea – thiocyanate solutions has been studied by the rotating-disc technique using ferric sulfate as oxidant. The effects of initial concentrations of ferric, thiourea (Tu) and thiocyanate as well as temperature and pH on gold leaching rates were studied. An initial gold leaching rate in the order of 10 − 9 mol ...
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Gold and Silver Leaching. For Gold and Silver, the most common leachants used are Na or K cyanides in the presence of oxygen, Thiourea (NH 2. CS.NH 2), also in the presence of oxygen, or Ammonium polysulphide (NH 4) 2 Sx, especially for Gold. Optimum physical conditions for cyanidation are: Maximum temperature of 85 o C, …
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Application of the thiourea-Fe3+ leaching system resulted in recovery of 16.4 ± 1.56 mg/kg of gold from the fine-grained PIR within 6 h of incubation. Due to high gold …
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The influence of particle size, thiourea and Fe (3+) concentrations and temperature on the leaching of gold and silver from waste mobile phones was investigated. Gold extraction was found to be ...
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Thiourea leaching from an oxidized gold-copper ore with 90-95% gold extraction was also reported (McInnes et al., 1989). However, acid pre-leaching of soluble copper was required in order to reduce thiourea consumption to acceptable levels. Ammoniacal Thiosulfate Leaching. Ammonium thiosulfate has been used in …
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support instructive information for the discovery and design of new highly efficient and environmentally friendly gold leaching reagents. Although there are many studies on gold leaching by thiosulfate (S2O3 2), thiourea (SC(NH 2)2), thiocyanate (SCN), and halogen, there is a lack of systematic wavefunction analysis of the gold …
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Moreover, thiourea leaching of Au was tested in pilot plants and industrial operations [28, 30]. The pH of the solution, leaching potential, ferric sulfate concentration, thiourea concentration and leaching time are critical parameters for the leaching efficiency . The optimum conditions for thiourea leaching can be achieved by using an ...
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Brine leach solution was prepared by adding 250 g/L NaCl to acidified water and heating to 55° C. Sufficient residue from the thiourea leach was added to the hot leach solution to vary the pulp density from 2 to 8.2 pct solids. The slurry was mixed for a specified time and filtered through a hot Buchner funnel.
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Besides, the addition of thiourea can also improve the gold extraction rate and the initial gold leaching rate form gold-bearing sulfide ores in thiosulfate solution [114]. 4.4 Pressurized oxygenâˆ'thiosulfate system In order to overcome the problem caused by the usage of ammonia and reduce the high consumption of thiosulfate …
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Gold leaching using thiourea (0.4 M thiourea, pH 1.5, 3 h) following pretreatment using HCl and Citrate and no pretreatment, M. Reprinted with perimission …
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It was found using a rotating disk experiment that when the leaching solution contained 1.0% thiourea, 0.5% sulfuric acid and 0.1% ferric ions, the rate of gold and silver dissolution was over 10 ...
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Thiourea leaching of gold from a quartz vein type ore without the addition of additive was investigated to show the effect of leaching conditions including Fe 3+ concentration (0.02–0.05 M), thiourea concentration (0.05–0.13 M), pH (1.0–2.5), leaching time (4–7 h) and temperature (25–50 °C) on gold extraction and thiourea consumption. . …
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Since the initial report of thiourea as a complexing reagent for gold leaching, considerable research has been directed toward the use of thiourea as an alternative to cyanide for gold extraction from different auriferous mineral resources. At the same time, some fundamental investigations of the system have been reported. In this …
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by thiourea leaching Gold leaching experiments were carried out in a 400 mL flask immersed in a thermostatically controlled water bath. Specific amounts of ferric sulfate solution, distilled water, ... added to the solution when the design temperature was achieved. After the desired reaction time had elapsed, the residue was separated from …
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The present paper is focused on the extraction of gold from high-grade e-waste, i.e., spent electronic connectors and plates, by leaching and electrowinning. These connectors are usually made up of an alloy covered by a layer of gold; sometimes, in some of them, a plastic part is also present. The applied leaching system consisted of an acid …
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In this study, the structure and properties of environmentally friendly gold lixiviants (thiosulfate, thiourea, thiocyanate, polysulfide, halogens, amino acid, humic acid, etc.) are reviewed; Table 1 summarizes the applications of environmentally friendly gold lixiviants. Moreover, the gold leaching mechanism of environmentally friendly gold …
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The chemistry of thioureation process. Gold (I) forms strong cationic complex with thiourea in acidic solution 2, 5: (1) Au°+2SC (NH 2) 2 =Au [SC (NH 2) 2] + 2 +e for significant leaching rate at this potential (above 0.4 V) an oxidant at high concentration (ferric ions or hydrogen peroxide) is required. The reduction of O 2 is slow at these ...
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The nature of gold (Au) ore deposits plays an essential role in determining the best gold recovery method as an alternative to cyanidation, considering environmental concerns. Thiourea (Tu) leaching of gold is an alternative lixiviant for treating sulfide gold ores and concentrates. The present study investigated the leaching behavior of Au from …
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The highest Au dissolution percentage of 96.2 was obtained after 6 h of leaching with 40 g/L thiourea at 60 °C, pH 1, and pulp density of 20 g/L. Based on the results presented in this work, the ...
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Thiourea Gold Leaching. The use of thiourea, (CS (NH2)2 as a complexing/extracting agent for gold and other precious metals has …
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August 1994. This paper investigated the factors influencing thiourea (Tu) consumption in the gold-leaching process with an acidic thiourea solution. The experimental results show that some of ...
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Baseline leach experiments have established the refractory nature of the concentrate. Roasting of this concentrate at 450-550°C for one hour prior to leaching has increased gold and silver extraction values to approximately 89% and 70% respectively by thiourea leaching, and 76% and 74% by cyanidation.
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The nature of gold (Au) ore deposits plays an essential role in determining the best gold recovery method as an alternative to cyanidation, considering environmental concerns. Thiourea (Tu) leaching of gold is an alternative lixiviant for treating sulfide gold ores and concentrates. The present study investigated the leaching behavior of Au from sulfide …
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Abstract. Thiourea was used to leach gold from ore containing 0.4% Cu and 5.6 g/t Au. The parameters studied were acid pretreatment, leaching time, pH, thiourea concentration and the oxidizing agents used. Gold extraction was 89% and thiourea consumption was 3.9 kg/t. No acid consumption was observed during leaching at pH 3.
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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.The plant, part of … See more
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The thiourea (TU) leaching of gold from refractory ores can be considered an alternative to cyanidation. However, the high reagent consumption causes an increase in cost, which seriously limits its use. In order to effectively reduce the TU consumption, it is necessary to analyze the influencing parameters of gold recovery and TU consumption …
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Gold leaching i n alkaline thiourea shows better selectivity than acidic thiourea leaching, which also deserves attention (Zheng et al., 2006). B ase metals such as Pb, Zn, and Cu are
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T1 - THIOUREA LEACHING OF GOLD AND SILVER - TECHNOLOGY UPDATE AND ADDITIONAL APPLICATIONS. AU - Hiskey, J. B. PY - 1984. Y1 - 1984. N2 - The hydrometallurgical application of thiourea in processing precious metal ores and concentrates has reached the development stage. This paper reviews recent technical …
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The plant, part of the FENIX project, consists of two hydrometallurgical technologies of which, GOLD REC 1, includes an oxidative base metal leaching method combined with thiourea leaching for ...
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