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Each hour during leaching thiourea was added in an amount of kg/ton the overall consumption was kg/ton The sorption leaching kinetics during fractional supply of thiourea 1 h % 2 h 22% 3 h 25% 4 h 31% 5 h 44% The maximum gold extraction is 44% with a duration of 5 h
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Dissolution is generally much faster in thiourea than in cyanide solution AB The review of recent literature relating to the use of thiourea as a lixiviant for gold and silver indicates only a modest level of activity and interest Alkali cyanide leaching system remains the popular choice for treating gold and silver ores
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Gold dissolves in acidic thiourea solution to form a stable complex 2Au 4CS NH2 2 2Fe3 = 2Au CS NH2 2 2 2Fe2 In the thiourea reaction ferric iron is used as an oxidizing agent whereas the cyanide process uses oxygen from the air dissolved in the leach solution Part of the ferric iron needed is most the time present in the ore
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Abstract 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
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Apr 27 2021I ve leach the gold in tiosulphate with catalizators ph = 11 86 and later put it on weak base resin Later I rinse the resin with hot about 50°C water to dissolve some copper tiosulphate which occurs on the resin Finally I took it up with thiourea in acid
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Inorganic salts of sulfurous acid Explore the latest full text research PDFs articles conference papers preprints and more on SULFITES Find methods information sources references or
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Explore the latest full text research PDFs articles conference papers preprints and more on PULP Find methods information sources references or conduct a literature review on PULP
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Explore the latest full text research PDFs articles conference papers preprints and more on PRINTED CIRCUIT BOARDS Find methods information sources references or conduct a literature review
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ABSTRACT The use of thiourea as an alternative lixiviant to gold cyanidation for processing gold bearing ores or concentrates was first developed by Soviet metallurgists in the 1940s However the interest for thiourea leaching of gold mainly came during the 1980s and 1990s to establish a parallel process The chemistry of thiourea is simpler than thiosulfate complexation with gold forming a cationic complex of gold
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The dissolution of gold in thiourea solutions was reported for the first time in 1941 and it was continued in 1960 It has been reported that gold dissolves [1] more efficiently with thiourea in acid than in alkaline solution Thiourea is un stable above pH = and its degradation is also caused by oxidation
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The review of recent literature relating to the use of thiourea as a lixiviant for gold and silver indicates only a modest level of activity and interest Alkali cyanide leaching system remains the popular choice for treating gold and silver ores
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Gold and Thiourea Science topic Gold A yellow metallic element with the atomic symbol Au atomic number 79 and atomic weight 197 It is used in jewelry goldplating of other metals as currency
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During the leaching tests 10 ml samples of solution were taken at regular intervals to study the dissolution rate of the gold and the consumption of thiourea At the end of the tests the leached solid sample was washed with acidified water by sulphuric acid at pH 1 and the filtration waters were also analysed for gold as was the residue after drying and milling
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Reaction mechanism of gold dissolving in alkaline thiourea solution was studied by electrochemical methods such as cyclic voltammetry chronopotentiometry AC impedance linear sweep voltammetry Apparent activation energy of anodic process of gold electrode dissolving in alkaline thiourea solution is kJ/mol Rate determining step is the process of gold thiourea complex diffusing away
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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 enhanced in a PCBs particle size of 100 mesh with the solutions containing 24 g/L thiourea and Fe 3 concentration of % under the room temperature
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Leaching of gold in acid thiourea thiocyanate solutions The leaching of gold in ferric thiourea thiocyanate solutions has been studied by the rotating disk technique The effects of initial concentrations of ferric thiourea Tu thiocyanate temperature and pH value on gold leaching rate were studied
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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 been reported that gold is dissolved more efficiently by thiourea in acidic solution than in alkaline solution
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Commercial applications of thiourea for gold leaching has been hindered for the following reasons Cui Zhang 2024 1 thiourea is more expensive than cyanide 2 since thiourea readily gets oxidized in solution its consumption in gold processing is very high and 3 steps involved in gold recovery process requires more development
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Gold leaching rate at pH higher than 11 in solutions containing M glycine and 1% peroxide at leaching temperature of 60 icance for copper gold preferable in the glycine peroxide system Table 2 shows the required amounts of caustic in mM to reach the targeted pH The cost of maintaining a high pH with NaOH rather than Ca OH
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Gold cyanidation also known as the cyanide process or the MacArthur Forrest process is a hydrometallurgical technique for extracting gold from low grade ore by converting the gold to a water soluble coordination complex It is the most commonly used leaching process for gold extraction [1]
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A method is provided for recovering gold and silver from precious metal bearing materials including ores leaching residues flue dust electronic scrap jewelry scrap etc In the method the gold and silver are extracted from the precious metal bearing materials with a thiourea solution to form a thiourea leach and the thiourea leach is contacted with carbon to adsorb the gold and silver and provide loaded carbon
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When thiourea is used for leaching gold from the calcine and the sulphide ore excessive Fe III is quickly reduced to Fe II by thiourea and the electrode potentials of the solution fell to a
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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
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Reaction chemistry of gold leaching in thiourea solution for a Turkish gold ore Hydrometallurgy 67 71 77 2024 Hiskey J B Thiourea Leaching of Gold and Silver Technology Update and
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China good quality manufacturer of Gold Leaching In Acid Thiourea Solutions are you finding high practical and durability of Gold Leaching In Acid Thiourea Solutions Company Details Changchun Gold Research Institute [Jilin China] Business Type Manufacturer Main Markets Worldwide Exporter 41% 50%
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01/01/1998· Thiourea is itself toxic and can be a carcinogen likepounds However the use of thiourea causes high reagent consumption and it is this consumption of thiourea which seriously limits its use The objectives of this study are to evaluate the use of thiourea in leaching the gold ore from the Agnico Eagle mine
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The reaction describing the dissolution of gold in acidic solutions of thiourea was given by Kazakov et al 1964 as Au 2CS NH2 2 Au CS NH2 2 e The reduction potential for this reaction is E= V on a fresh gold sur face but on a passivated surface this increased to E= V Groenewald 1975
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دانلود رایگان مقاله انگلیسی ISI بخشی از متن مقاله Abstract All the industrially applied gold leaching methods historical chlorine gas based leaching dominating state of the art cyanide gold leaching processes at precious metals plants suffer from the characteristics related to aggressive and even toxic leaching media and high chemical consumption
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Thiourea is thought to be a low toxicity reagent that exhibits a faster gold leaching rate with apparently less interference from the base metals Pb Co Ni Zn moreover it is used in acidic conditions rather the alkaline conditions of cyanide and thiosulphate Yannopoulos 1991
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Aug 9 2022Application of the thiourea Fe 3 leaching system resulted in recovery of ± mg/kg of gold from the fine grained PIR within 6 h of incubation Due to high gold market prices upscaling of the suggested technology can represent a suitable strategy for gold recovery from PIR and other MSWI residues
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