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it is environmentally friendly and easy to operate [16,17]. The leach-ing of gold is one of the most important steps in the hydrometal-lurgical process. Generally, gold leaching methods can be categorized according to the leaching chemicals, like cyanide leaching, halide leaching, thiourea leaching, thiosulfate leaching, etc. The pros and
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Table 4 Summary of selected US patents related to gold extraction/recovery US Patent No. Title 4,578,163 Gold recovery process Date Summary of Process 25/3/86 Treatment of refractory ores Pressure oxidation, cyanidation and CIP recovery Flowsheet provided in Appendix A 4,597,791 Gold recovery processes 1/7/86 4,681,628 Gold recovery …
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Under the optimal leaching conditions of lixiviant concentration 0.3 wt%, initial pH 10–11, liquid to solid ratio 2.5:1, and agitation speed 600 rpm, the synthetic lixiviant could achieve a gold ...
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Cyanidation simulation predicted 98.5% gold recovery, whereas the halide leaching indicated a final gold recovery of only …
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The addition of 15 g/L of activated carbon to the pregnant leach solution (PLS) could provide recovery of gold from solution onto activated carbon, i.e. holistic recovery of 90%.
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The utilization of cyanide in the gold leaching process presents risks to environment and health, therefore an economically viable and selective method while minimizing the risks is a very ...
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In the second stage, the separated residue is used for the recovery of gold by sulphuric acid with a combination of halide salt. Results have shown that almost 92% of gold is recovered at the optimized parameters. Solvent extraction with 0.1M tertiary amide reveled the selective and quantitative recovery of gold from gold leach solution.
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Gold is a highly required material for a wide range of personal and industrial applications. The high demand for gold, together with the shortage of natural resources …
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gold from other resources such as refractory ore and electrical and electronic equipment. The normal method of leach-ing for gold is cyanide leaching, but it is very dangerous …
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However, with the increasing refractory nature of gold ores and restrictions on cyanidation, interest in halide-based gold leaching processes was renewed in the 1990s (Tran et al., 2001). The chronology of using halides as gold lixiviants is …
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In this work, we combine the delamination of WPCBs obtained from end-of-life mobile phones, the oxidative leaching of the metallic fractions, and the separation and recovery of copper and gold by solvent extraction to define a technically feasible process that can recycle these valuable metals from e-waste (Fig. 1).In contrast to previous …
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The stability of gold-halide complexes is dependent on the Eh-pH in the solution, composition, and the nature of ores to be processed. The elimination of in situ loss of gold via adsorption with carbonaceous matter and the detoxification of free cyanide are the main advantages for using chlorine leaching.
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Research on the leaching of gold by thiourea has been reported extensively in the literature, but research on the recovery of gold from leach solutions has not been well documented. Some methods for …
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Recovery gold from the leaching residue by enhanced chlorination roasting. In a typical roasting procedure, a certain amount of calcium chloride, leaching residue and pyrite were thoroughly blended with a certain mass ratio. Subsequently, put 20.0 g pre-prepared samples into corundum porcelain boat and pushed to the tube furnace. ...
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Halide gold leaching. The use of halide (fluorine, chlorine, bromine, iodine and astatine) systems for gold dissolution pre-dates cyanidation (La-Brooy et al., 1994). With the exceptions of fluorine and astatine, all halogens have been tested and used for gold extraction (Moir, 1906). Earlier to the inception of cyanide, chlorine was ...
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Halide leaching. This treatment method includes chloride [23], [24], bromide [25], and iodide leaching [26], [27], [28]. The reaction scheme is shown below. ... Gurung et al. reported the acidothiourea-based recovery of gold, wherein PCB leach liquor was found to be rich in gold when a mixture of 0.5 ...
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Cyanide is a lixiviant, or reagent that is used to leach, often in tanks, gold from a solid matrix and form a gold cyanide complex. The gold cyanide complex is then extracted from the pulp or slurry by adsorption onto activated carbon. CIL stands for carbon-in-leach. This is a gold extraction process called cyanidation where ... Gold …
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The substitutes for cyanide can be classified as traditional and novel non-cyanide gold leaching reagents. The traditional alternatives mainly include thiourea, halide, polysulfide, thiocyanate, lime sulfur synthetic solution (LSSS), and thiosulfate (Hilson and Monhemius, 2006, Sun et al., 2020, Xing et al., 2019).Although considerable …
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As can be seen, the Au recovery is strongly affected by the leaching time. It can be seen that the leaching time has the most influence on gold leaching. In addition, the recovery of gold reduces with increasing pH in the range investigated. It is obvious that the high gold recovery is achieved at the highest leaching time and the lowest pH value.
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The recovery of gold, due to its high value, is one of the main motivations for recycling e-waste. ... This review aims to provide an up-to-date evaluation of thiourea-gold leaching studies from ...
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The main steps in the direct chloride leaching process are as follows: atmospheric leaching, gold recovery by solvent extraction (SX), gold reduction, and neutralization steps. ... The results suggest that the circulation of leaching chemicals is critical in developing an environmentally viable halide leaching process for gold.
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The main steps in the direct chloride leaching process are as follows: atmospheric leaching, gold recovery by solvent extraction (SX), gold reduction, and …
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In order to investigate the pulp density on gold leaching, experiments were performed for 10%, 20% e 30% of solids (w/v) with solutions of 25 g/L of Ca(OCl) 2, 15 g/L of NaCl and pH 4–6 (Fig. 4). As in Fig. 4, in all three cases leaching occurred with similar kinetics and the gold recovery stabilised within the first 30 min of test ...
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The leaching kinetics of gold in a chloride medium is proportionally dependent on the chlorine-chloride concentrations. A pretreatment of carbonaceous or sulfidic ores is …
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Wu et al. fabricated a polyaniline polymer and applied it to gold adsorption from a halide leaching solution of e-waste ... Quinet et al. proceeded with the leaching …
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The selective recovery and separation of gold from leach liquor have been achieved with solvent extraction with an organic amide as extractant followed by cementation with zinc powder. ... (Eh) vs. pH diagram for the feasibility of gold in halide medium revealed that leaching of gold is possible [13,15,17]. 2NaBr + 3H 2 SO 4 → …
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Fine gold particles can be recovered in other concentration devices such as flotation and/or leaching. SAG mill circuit. Gold Recovery. Gold recovery comprises similar stages to the processing of most ores. First, the valuable minerals are separated from the gangue through concentration. The final concentrate is obtained by repeated …
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The objective of this paper is to assess four different organic halides as leaching agents for gold recovery from WEEE. Two of them have been previously tested (namely N-bromosuccinimide, NBS, and N-chlorosuccinimide, NCS) and have shown promising results, whereas the other two are novel and were selected due to their lower …
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The physical and chemical properties of gold promote its application, such as in the high-tech, electronic products, and aerospace industries. The easily leachable ore is gradually depleted. Thus, it becomes necessary to extract gold from other resources such as refractory ore and electrical and electronic equipment. The normal method of …
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Halide leaching system is comparatively less attractive because of the strong causticity of the lixiviant [15]. The limited availability of thiocyanate to the temperature and solution pH is a significant restriction in gold leaching and if thiocyanate has to be detoxified by oxidation to cyanate and sulfate, it would further increase the ...
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