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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 article, a review of both …
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The next step after leaching in the hydrometallurgical gold processing is the recovery of gold from the solution. In the gold mining industry, activated carbon is the most widely used extractant to recover gold from pregnant cyanide leach solution, known as carbon-in-leach (CIL), carbon-in-pulp (CIP), and carbon-in-columns (CIC) processes ...
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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.
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Thiourea leaching of gold from processed municipal solid waste incineration residues ... In the rst stage the alkalic ne-grained PIR was acidied with a solution of 20% (v/v) of HCl-containing ue ...
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Au (solution) is the amount of gold in the thiourea solution, Au (solid) is the amount of gold in the feed sample before the leaching process, and Vt is the total volume of solution (l), and [Au ...
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Currently, the adsorption methods (e.g., CIP / CIL) are by far dominating the recovery of gold from leaching solutions, especially in cyanide media.
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Thiourea leaching of gold has attracted much attention because of its environmentally friendliness. Gold recovery from high-grade e-waste, uranium tailing material, mature dumps, etc., using thiourea leaching has been widely studied [1,2,3,4,5].In recent years, to overcome the disadvantages of acidic thiourea gold leaching, research has been undertaken …
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The invention discloses a kind of method of Gold Leaching In Thiourea Solutions; when with acid thiourea solution gold lixiviation; source of gold deposits is contained for different; as oxidized ore, soak the ore pulp after sulphide ores or calcining, by ore pulp acidity control at 2.2 & lt through oxidation pre-treatment (Oxidation under pressurized oxygen, bio-oxidation or roasting ...
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SYMBOLS AND ABBREVIATIONS Symbols °C degree Celsius g.cm-3 gram per cubic centimeter g.kg-1 gram per kilogram g/l gram per liter g/t gram per ton kg/t kilogram per ton mg.l-1 mass concentration, milligram of the given substance per unit volume (liter) ml milliliter
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reagent, high selectivity towards gold, faster leaching kinetics, the possibility of uncovering gold and silver included in acid-soluble minerals, lower dependence of efficiency on the presence of impurity ions. Dissolution of gold in thiourea solutions proceeds in the presence of an oxidizing agent [5, 6] by the following reaction:
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In this paper, oxalate and citrate were used as additives to enhance the thiourea leaching of gold from a gold ore. The leaching results showed that the thiourea consumption …
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Prior to leaching, the gold concentrate was subjected to a series of washes and cleaning with CaClO 3, and regulating the pH with Ca(OH) 2. In addition, oxygen was used as oxidant agent for cyanide leaching, and H 2 SO 4 as oxidant agent for thiourea leaching. The control of the potential of solution was performed using a multimeter connected ...
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The thiourea process has been most widely studied mainly because thiourea is not detrimental to the environment, nontoxic to humans, and the dissolution of gold in thiourea solutions is much faster than in cyanide solutions. Dissolution of gold in thiourea solution was reported first in 1941 and continued in 1960s (Lin and Huarng, 1994). It has ...
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The chemistry of thiourea is simpler than thiosulfate complexation with gold, forming a cationic complex of gold. Various oxidants like oxygen, ozone, sodium peroxide, hydrogen peroxide, ferric ions, dichromate, and manganese dioxide are employed to enhance the leaching of gold in thiourea solution.
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Numerous non-cyanide leaching lixiviants have been developed, among which thiosulfate is considered the most promising alternative to cyanide due to its non-toxicity, low …
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In addition, recent fundamental contributions are discussed. Most of the interest in thiourea leaching has involved treating high grade concentrates that have sufficient value to justify the use of thiourea as a reagent. An important development in thiourea technology is the addition of SO//2 to the leaching solution.
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Thiourea leaching of gold, despite rst being reported in 1941 [54], has never been clearly established into industry. Only a few industrial applications were reported between
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The invention discloses a method for gold leaching by thiourea. When the gold is leached by an acid thiourea solution, aiming at the different gold-containing mine resources, such as the oxidized ore, and the ore pulp or the roasted sand which is obtained after by the hardy-leached sulphide ore is pretreated (oxidized under oxygen pressure, biologically oxidized or roasted) by means …
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Yang (Yang et al., 2011) studied a mixed gold leaching system of thiocyanate and thiourea; the results showed that the mixed gold leaching reagents had a synergistic effect on the dissolution of gold, in which the mixed coordination compound Au(SC(NH) 2) 2 SCN was formed. In the thiocyanate solution, the dissolution of gold is a surface ...
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Desired amount of jarosite powder was added into 100 mL acidic thiourea solution for each leaching. Gold foil was suspended in the upper part of the pulp by a nylon thread in order to avoid its contact with the inner wall of beaker. All tests were conducted under the conditions of TU 2 …
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The thiosulphate solution can form an anionic complex [Au(S 2 O 3 ) 2 ] 3− with gold under alkaline conditions, while thiourea solution can form cationic complex Au[CS (NH 2 )] 2 + in acidic ...
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(DOI: 10.1080/08827500500339315) 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 article, a …
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an oxidative base metal leaching method combined with thiourea leaching for gold and silver [55]. Despite this limited industrial use, thiourea as a leaching reagent has successfully bridged the transition from primary leaching of ores to gold and silver leaching from secondary sources such as e-waste. The excessive consumption of thiourea,
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Reaction of gold in alkaline thiourea solution.—The dissolution of gold in thiourea solution generally proceeds according to the fol-lowing reaction Au[CS(NH2)2]2 1 1 e 5 Au 1 2CS(NH 2)2 E 0 5 0.38 V [1] By the addition of oxidants, thiourea can be oxidized in successive stages to form several products. The first product is formamidine
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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 from [66]
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Whereas some accompanying elements like Se, Te, V, Cr and Ni in the concentrate were insoluble in the acidic thiourea solution. Gold was recovered from the leach liquor by adsorption on the ...
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from thiourea‑Fe 3+ leaching solution Our results have sho wn that the efficiency of Au mobilization by the thiourea-Fe 3+ system from acid-treated fine-grained
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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 gold ore concentrates obtained from the Cripple …
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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 dissolution of gold with thiourea in an acidic solution would be a potential alternative to the traditional cyanide process, with the increase in ...
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Gold leaching by thiourea has been investigated in an alkaline solution. In the presence of both Na2SO3 and Na2S2O8, the chemi-cal dissolution of gold can be …
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