· Ammonium thiosulfate is a noncyanide lixiviant for gold leaching. However, the major problem with this leaching method has been the high consumption of reagents. To leach a mildrefractory copperbearing gold ore, the authors used a reagent combination of (NH4)2S2O3, CuSO4 and 3M NH3 at pH for 24 hours. In the testing, thiosulfate consumption was 30 kg/t of .
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challenges, thiosulfate has been applied in pilot plant since the 1980s, and has been used in heap leaching processes by Newmont Gold (Wan et al., 1994). Industrially, Barrick Gold has implemented a calcium thiosulphate retrofit at their Nevada operations (Choi, 2013). A development of in situ gold leaching using ferric EDTA and ferric oxalate complexes in thiosulfate solutions has been ...
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thiosulfate leaching of gold (Jiang et al, 1993a) 38 Figure Mechanism of gold leaching in ATS system in the presence of copper ion (Ouyang, 2001) 42 Figure The electrochemical model for the copper alysis mechanism of leaching gold with ammoniacal thiosulfate.( Aylmore et al, 2001a) 43 Figure The effect of pyridine on gold leaching in ATSCu system 45 Figure A diagram of ...
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Fundamental aspects of gold leaching in thiosulfate solutions. Creator. Li, Cheng. Publisher. University of British Columbia. Date Issued. 2003. Description. The kinetics and mechanism of gold leaching in the ammoniathiosulfatecopper (ATSCu) system have been studied using the rotating electrochemical quartz crystal microbalance (REQCM).
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· The method using thiosulfate as noncyanide gold recovery chemicals is usually carried out at 5060 ° C, and Cu2+, SO2 and sulfite are added as stabilizers to prevent the decomposition of thiosulfate ions. The pH of the leaching solution was adjusted by ammonia solution. The characteristics of using thiosulfate as a gold recovery chemicals are: (1) nontoxic, (2) fast leaching speed ...
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· Thiosulfate was chosen for insitu or inplace leaching of gold as it is more environmentally friendly than cyanide, however its stability and rate of gold recovery is .
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Thiosulphate leaching is a process that removes gold from gold bearing ores without the use of cyanide. Although not as aggressive a leaching agent as cyanide, thiosulphate offers several technological advantages including its lower toxicity and greater efficiency with gold deposits associated with pregrobbing ores. The thiosulphate leaching process, followed by resininpulp gold extraction ...
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A comparison of thiosulfate with cyanide leaching of gold from carbonaceous ore showed that thiosulfate is chemically better and economically more advantageous. Description. Online access for this thesis was created in part with support from the Institute of Museum and Library Services (IMLS) administered by the Nevada State Library, Archives and Public Records through the Library Services .
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The leaching of gold ores by acid solutions of thiocyanate produces two complexes, Au(SCN)2 and Au(SCN)4. The reaction involves oxidation. It is believed that the addition of Iron III is a good oxidant. Trying to add oxygen is not a good option because the gold dissolution will be very slow. Also the addition of iron tends to make more stable the thiocyanate. Use the Social Share Bar on the ...
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· The research into leaching of gold with thiosulfate as an alternative lixiviant to cyanide has predominantly involved the use of copper in the presence of ammonia which serves as the oxidant. However, there are concerns about the health and environmental risks of ammonia (or ammonium). At CSIRO continued research has been carried out to look for different oxidants for the thiosulfate leaching ...
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· Sodium thiosulfate, as a common reagent, has been used in many appliions, such as silver recovery in photographic process and leaching of gold from mines. In the goldleaching process, sodium thiosulfate works as a complexing agent. The reaction is complied but can be briefly expressed as the following equation
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Thiosulfate leaching of gold ores has great potential to reduce the impact on the environment. Unlike cyanide, which is highly toxic, the chemicals used in the thiosulfate leaching process are benign. This technology offers great potential in those jurisdictions where the use of cyanide is banned outright, or is subject to intense negative publicity for environmental reasons ; This process ...
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Based on the diagrams, a possible mechanism for the Co(III)/Co(II) electrochemicalalytic leaching of gold with ammoniacal thiosulphate is proposed. The calculation also reveals the differences in the oxidization potential and structural stability of the Co(NH3)(6)(3+) and Cu(NH3)(4)(2+), which explains the much reduced thiosulphate consumption in the CoNH3S2O32H2O system compared to ...
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· Thiosulfate has been considered as one of the most promising of the nontoxic alternatives to cyanide for the leaching of gold and much work has been carried out with the aim of understanding and improving the ammoniacal thiosulfate leaching process. In particular the behaviour of gold in thiosulfate solutions containing copper in the absence of ammonia has received little attention. It has ...
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· Thiosulfate leaching of gold and silver has been known since 1858. In the Patera process, which was used for silver recovery for many years (Lidell 1945), silver was extracted from silver chloride by sodium thiosulfate leaching of chloridizingroasted ores and concentrates. It was also recognized that unreacted silver sulfide could be leached when copper sulfate was added to thiosulfate ...
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· A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated. Mineralogical studies on the concentrate showed that very fine gold grains (<10 μm) were encapsulated in pyrite and arsenopyrite, while the proportion of monomer gold was only 21%. The goldbearing sample was identified as a highsulfur finesized wrappedtype refractory gold ...
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· The gold leaching process followed the pseudosecond order kinetic model at the low concentration range of the reactants such as 40–60 mM thiosulfate, 5–7 mM copper(II) and – M ammonia, and the pseudofirst order kinetic model at the mid concentration range (60–70 mM thiosulfate, 7–9 mM copper(II) and – M ammonia).
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· · Ahern, N. Thiosulfate Degradation during Gold Leaching in Ammoniacal Thiosulfate So lutions: A Focus Trithionate. Ph .D. Thesis, Univer sity of British Columbia, V anc ouv er, BC, Canada, October ...
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The thiosulfate lixiviant system for leaching of gold has been under extensive investigation for nearly two decades and consists of ammonium thiosulfate, copper and ammonia.
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Thiosulfate leaching can be considered a nontoxic process, the gold dissolution rates can be faster than conventional cyanidation and, due to the decreased interference of foreign ions, high ...
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