alkaline thiourea leaching gold

  • Study on the Gold Leaching Process by Potassium Ferricyanide

    Study on the Gold Leaching Process by Potassium Ferricyanide

    Leaching of middlerefractory gold ore show that both of the consumption of thiosulfate and leaching rate was decreased compare to the traditional copperammonia thiosulfate system. Thiourea is not stable in base solution, but it was found that gold dissolution rates can be increased with a little thiourea ,the mechanism is still unclear.

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  • US4778519A Recovery of precious metals from a thiourea

    US4778519A Recovery of precious metals from a thiourea

    The method is characterized by the step of contacting thiosulfate ion with the carbon loaded with the precious metals from the thiourea solution. The thiosulfate ion (preferably in alkaline solution) desorbs (elutes) the precious metals from the carbon. The precious metals are preferably gold and/or silver.

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  • Leaching goldsilver ores with sodium cyanide and thiourea

    Leaching goldsilver ores with sodium cyanide and thiourea

    There is currently much interest in how extraction of gold and silver from ores with acidic thiourea solution compares with extraction using alkaline cyanide solution. Agitation leaching tests were performed by the Bureau of Mines on 14 precious metal ores using sodium cyanide (NaCN) and thiourea

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  • The leaching of gold, silver and their alloys in alkaline

    The leaching of gold, silver and their alloys in alkaline

    in the presence of thiourea (0.220.25 mol/m2 s). In alkaline glycinehydrogen peroxide solutions, it has been found that gold leach rate from goldsilver (50% Ag) alloy is about 6 times higher than rate from pure gold and the silver leach rate was 0.247 mol/m2 s. An induction period of 48 h

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  • An innovative thiourea gold leaching process ScienceDirect

    An innovative thiourea gold leaching process ScienceDirect

    An additional advantage over cyanide exists when treating refractory sulphide goldcontaining ore, requiring biooxidative pretreatment; this results in highly acidic solutions, requiring neutralization prior to cyanidation, which takes place in alkaline solutions. In contrast, thiourea leaching occurs in acidic solutions that can be treated directly 7, 8.

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  • Mechanism of gold dissolving in alkaline thiourea solution

    Mechanism of gold dissolving in alkaline thiourea solution

    gold electrode dissolving in alkaline thiourea solu tion is 14.91 kJ/mol. Rate dete rmining step is the process of gold thiourea comple x diffusing away from electrode surface to solution. The

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  • Research status and prospect of gold leaching in alkaline

    Research status and prospect of gold leaching in alkaline

    The leaching rates of the coexisting metals in gold ores were less than 0.1% in alkaline thiourea system, which indicated that gold leaching in alkaline thiourea retained excellent selectivity.

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  • CN103276206A Method for leaching gold in alkaline

    CN103276206A Method for leaching gold in alkaline

    The invention discloses a method for leaching gold in an alkaline thiourea system efficiently and stably. According to the method, under an alkaline condition, thiourea is taken as a gold leaching reagent, sodium hexametaphosphate or trisodium phosphate is taken as a stabilizing agent, calcium peroxide is taken as an oxidizing agent, EDTA (ethylene diamine tetraacetic acid) is taken as a

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  • Hydrometallurgy Leaching in Heap, Vat, CIL, CIP, Merrill

    Hydrometallurgy Leaching in Heap, Vat, CIL, CIP, Merrill

    I should note that the research by Wang (2005, 2006) found that alkaline thiourea is selective in only leaching gold (and possibly silver), unlike cyanide (at high pH) or acidic thiourea which does leach heavy metals in addition to gold.

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  • Mechanism of gold dissolving in alkaline thiourea solution

    Mechanism of gold dissolving in alkaline thiourea solution

    In alkaline thiourea solution, gold dissolving mechanism undergoes the following courses adsorption of thiourea on electrode surface; charge transfer from gold atom to thiourea molecule; Au[SC(NH2)2]ads + receiving a thiourea molecule and forming stable Au[SC(NH2)2]2 +; and then Au[SC(NH2)2]2 + diffusing away from the electrode surface to solution

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  • A REVIEW OF GOLD LEACHING IN ACID THIOUREA SOLUTIONS

    A REVIEW OF GOLD LEACHING IN ACID THIOUREA SOLUTIONS

    Aug 31, 20060183;32;No passivation of the gold surface is observed in simple acidic solutions. However, in actual leaching systems, some sulfide minerals significantly catalyze the redox reaction between thiourea and ferric ion, causing high thiourea consumption if ferric ion is present in excess.

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  • DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

    DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

    Dissolution of gold with cyanide replacing reagents 271 Dissolution in thiourea is shown as 3+Au + 2 SC(NH 2) 2 + Fe Au[SC(NH 2) 2] 2 + + Fe2+. (4) The reaction is sensitive to pH and redox potential. Thiourea is intrinsically unstable and decomposes rapidly to substances that are unable to leach gold (Murthy, 1996; Aylmore, 2005)

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  • Alternative lixiviants to cyanide for leaching gold ores

    Alternative lixiviants to cyanide for leaching gold ores

    In practice, thiourea leaching of gold is typically performed at thiourea concentrations of 0.13 M (10 g/L), ferric ion concentrations of 0.09 M (5 g/L), pH values of 13 and at potentials between 0.4 and 0.45 V

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  • Cyanide and Other Lixiviant Leaching Systems for Gold with

    Cyanide and Other Lixiviant Leaching Systems for Gold with

    All systems require an oxidant to oxidise gold and a ligand to complex with gold in solution. Adjustment of pH is usually necessary. Alkaline lixiviant systems (pH gt; 10)include cyanide, ammoniacyanide, ammonia, sulphide, nitriles, and a few other minor possibilities.

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  • Cyanide Leaching Of Gold Mine Engineer.Com

    Cyanide Leaching Of Gold Mine Engineer.Com

    Most cyanide leaching is carried out at a alkaline pH of between 10 and 11, depending upon lab testing of individual ores and the optimum leaching/chemical use rates. The cyanide solution strength is also important in leaching gold, with the typical range of solution being in the 0.02% 0.05% NaCN.

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  • Dissolution Behavior of Gold in Alkaline Media Using Thiourea

    Dissolution Behavior of Gold in Alkaline Media Using Thiourea

    understanding of the goldthiourea system in an alkaline environment, and to establish the most favorable conditions for the leaching. 2. Methodology 2.1. Chemical Speciation The chemical speciation diagrams are constructed to show the relation of the different chemical species (thiourea and goldthiourea) either as a function of

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  • A Method for Leaching or Dissolving Gold from Ores or

    A Method for Leaching or Dissolving Gold from Ores or

    The hydrometallurgical leaching of native gold from goldbearing ores or the dissolution of gold metal during the recycling of electronic and precious metal scrap is performed every day using hazardous chemicals such as sodium cyanide or aqua regia. These chemicals represent health and safety risks for workers and a serious threat for the

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  • DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

    DISSOLUTION OF GOLD WITH CYANIDE REPLACING REAGENTS

    queries. The aim of this paper is to study leaching of gold with cyanide replacing alternatives such as ammonium thiosulfate, chloridehypochlorite, thiourea and thiocyanate to provide new cases for the tool. The behaviour of gold was examined with electrochemical tests and weight loss measurements a using

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  • An innovative thiourea gold leaching process ScienceDirect

    An innovative thiourea gold leaching process ScienceDirect

    An additional advantage over cyanide exists when treating refractory sulphide goldcontaining ore, requiring biooxidative pretreatment; this results in highly acidic solutions, requiring neutralization prior to cyanidation, which takes place in alkaline solutions. In contrast, thiourea leaching occurs in acidic solutions that can be treated

    Get Price
  • The leaching of gold, silver and their alloys in alkaline

    The leaching of gold, silver and their alloys in alkaline

    In alkaline glycinehydrogen peroxide solutions, it has been found that gold leach rate from goldsilver (50% Ag) alloy is about 6 times higher than rate from pure gold and the silver leach rate was 0.247 mol/m 2 s. An induction period of 48 h was noted for rolled precious metal foils, after which leaching rapidly accelerated.

    Get Price
  • CN103276206A Method for leaching gold in alkaline

    CN103276206A Method for leaching gold in alkaline

    According to the method, under an alkaline condition, thiourea is taken as a gold leaching reagent, sodium hexametaphosphate or trisodium phosphate

    Get Price
  • Leaching GoldSilver Ores With Sodium Cyanide and

    Leaching GoldSilver Ores With Sodium Cyanide and

    Cyanide extracts gold in an alkaline medium, and although no oxidant other than air from agitation is generally applied, addition of an oxidant may be beneficial (4). The dissolution of gold by cyanide iy expressed by with gold solubilized as an anionic complex.

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  • CN103276206B Method for leaching gold in alkaline

    CN103276206B Method for leaching gold in alkaline

    The present invention discloses a method of highly efficient and stable system for alkaline thiourea leaching gold, which is under alkaline conditions, leaching of gold thiourea as an agent, trisodium phosphate or sodium hexametaphosphate as stabilizer, calcium peroxide as the oxidant, EDTA infusion to help rapidly from gold ore (tailings), gold powder and gold containing waste, effective

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  • Research status and prospect of gold leaching in alkaline

    Research status and prospect of gold leaching in alkaline

    Gold leaching in acidic thiourea solution exists series of problems, such as higher consumption of thiourea during gold resolution, serious corrosion of equipments in acidic solution, no selectivity of gold leaching, complicated regeneration and purify procedures of lixiviums.

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  • Electrochemical behavior of gold and its associated

    Electrochemical behavior of gold and its associated

    Jul 11, 20180183;32;L.Y. Chai and M. Okido, Dissolution theory of gold in alkaline thiourea solution (II) electrochemical study on AuFe mix anode in alkaline thiourea solution containing Na 2 SO 3, S. Zheng, Fundamentals of Green Process of Gold Leaching in Alkaline Thiourea Solution with High Stability [Dissertation], Central south university, Changsha, 2006.

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  • Alternatives to cyanide in the gold mining industry what

    Alternatives to cyanide in the gold mining industry what

    Moreover, if using cyanide to treat refractory sulphide goldcontaining ores, which have been preoxidised to release the gold, the highly acidic solutions produced must be neutralised prior to cyanidation, whereas thiourea can be used directly, since gold leaching occurs in acidic solutions .

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  • A fundamental study of the alkaline sulfide leaching of gold

    A fundamental study of the alkaline sulfide leaching of gold

    In the present paper, a kinetic study of gold leaching in alkaline sulfide solutions is presented. For the gold leaching system, both a complexing lixiviant and an oxidant are required to effect dissolution. It will be shown that sulfide is an effective lixiviant, and the polysulfides are effective oxidants. 2. EXPERIMENTAL

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  • Dissolution Behavior of Gold in Alkaline Media Using Thiourea

    Dissolution Behavior of Gold in Alkaline Media Using Thiourea

    In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thioureaalkaline medium. A thermodynamic study was conducted by chemical speciation using the method of RojasHern225;ndez, together with an

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  • Thiourea Gold Leaching Metallurgist amp; Mineral Processing

    Thiourea Gold Leaching Metallurgist amp; Mineral Processing

    Use of acidic thiourea instead of cyanide would allow for immediate leaching of gold without neutralization and result in considerable savings through the elimination of the neutralization step. For the thiourea process to compete industrially with cyanidation, it is essential to develop efficient process(es) to recover the gold from solution.

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  • Dissolution Behavior of Gold in Alkaline Media Using Thiourea

    Dissolution Behavior of Gold in Alkaline Media Using Thiourea

    The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH; by increasing the initial concentration of thiourea at alkaline pH, the presence of the gold complex is almost zero for any initial concentration of thiourea.

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