The acid-insoluble metal sulfides FeS2, MoS2, and WS2 are chemically attacked by iron (III) hexahydrate ions, generating thiosulfate, which is oxidized to sulfuric acid. Other metal sulfides are attacked by iron (III) ions and by protons, resulting in the formation of elemental sulfur via intermediary polysulfides. Sulfur is biooxidized to sulfuric acid. This explains …
Gold leaching is the key stage in process of gold mining. There are a few well-reputed leaching methods using a variety of different reagents. Nowadays the most popular industrial processes include cyanide, thiourea, and thiosulfate leaching methods.
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To better understand the dissolution process of pure metal in aqueous solutions, the kinetics of gold leaching with copper–tartrate–thiosulfate solutions were carried out using a pure gold disc technique. The effects of temperature, initial pH, copper, tartrate, and thiosulfate concentrations on the gold dissolution process were examined.
Heating up the sand in hot acetic acid (vinigar), HCl, crushing, Panning is useless unless well crushed. The pieces of gold I found under magnification splashed on the little pieces of rock, under the black, dont make the piece heavy enough to pan. Too much rock too little gold. Some guys tumble it in with a few bigger rocks of quartz to a …
Fundamental studies on thermodynamic and kinetic aspects of the dissolution of gold and oxidation of thiosulfate in copper (II)–ammonia–thiosulfate solutions based on species distribution, Eh–pH diagrams and kinetic models pave the way to rationalize the complex chemistry involved in leaching and provide information which can be used to …
A Review of Thiosulfate Leaching of Gold: Focus on Thiosulfate … WebJun 15, 2017 Thiosulfate leaching is a promising alternative to cyanidation, and the main hindrances for its wide commercial application are the high thiosulfate consumption and the difficult recovery of dissolved gold.
In this study, diphenylphosphine (DPP) diluted in benzene was used to extract gold from thiosulfate solution, and its extraction behavior and properties were investigated. The effects of the DPP concentration, pH value, contact time, and sodium thiosulfate concentration on the extraction performance were evaluated.
The effect of pyrite and the role of ammonium alcohol polyvinyl phosphate (AAPP) during gold leaching in ammoniacal thiosulfate solutions were investigated using pure gold foils. The results showed that pyrite catalyzed the decomposition and also significantly increased the consumption of thiosulfate. This detrimental effect became …
Thiosulfate leaching-resin adsorption recovery, an environmentally friendly process, has been developed to efficiently extract gold from an oxide gold concentrate. 80.5% of gold extraction could be achieved by thiosulfate leaching under …
The most tested leaching agents for gold are thiosulfate, thiourea, thiocyanate and halides [ 19, 20, 21 ]. An effective Au recovery process from mining …
The gold leaching kinetics were found to be chemically controlled and the rate was found to decrease with time as the copper (H) concentration decreased. This can be attributed to passivation of the gold surface by …
To better understand the dissolution process of pure metal in aqueous solutions, the kinetics of gold leaching with copper–tartrate–thiosulfate solutions were …
The acid-insoluble metal sulfides FeS 2, MoS2, and WS2 are chemically attacked by iron (III) hexahydrate ions, generating thiosulfate, which is oxidized to sulfuric acid, explaining leaching of metal sulfide by Thiobacillus thiooxidans.
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 …
Recent research has pointed to thiosulfate as one of the most promising nontoxic alternatives to cyanide in gold leaching. Researchers have achieved varying degrees of …
The application of pressure oxidation (POX) followed by thiosulfate gold leaching is an efficient method used to extract gold from double refractory gold ores containing both sulfide and carbonaceous matter. This process is expected to result in high gold recovery rates, as it liberates gold from sulfides and eliminates the preg-robbing …
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Thiosulfate leaching has been regarded as a promising alternative to cyanidation, but it still faces the challenge of the recovery of low content of gold from high concentrations of thiosulfate solutions. Liquid–liquid extraction is a method to address this issue but is still limited by the use of volatile and toxic organic solvents. To overcome …
This literature review provides an update of ammoniacal thiosulfate as a potential lixiviant of gold, the history of thiosulfate leaching and recent progress on thiosulfate leaching of gold, as well as the production, oxidation, and stabilization of thiosulfate. The leaching results of different types of gold ores including oxide, sulfide, …
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 preg-robbing ores. The thiosulphate leaching …
The leaching reaction of silver from the burrows, in the oxygen–thiosulfate–copper system involves two types of silver compounds that were adequately leached (metallic silver and silver sulfide).
Sodium Thiosulphate Gold Leaching. The gold industry has been seeking alternative reagents for leaching gold from low-grade ores for the past 25 years. The cost and transport of cyanide, the poor recovery of gold from carbonaceous ores, the lack of selectivity of cyanide towards copper minerals and the cost of waste treatment are real …
In this research gold and silver were recovered from Waste Printed Circuit Boards (WPCBs) with the use of ammonia-thiosulfate solutions and the MTA 5011 ion exchange resin. First, it was necessary to remove the excess of copper from WPCBs since it could be detrimental for precious metals dissolution during leaching with thiosulfate.
The leaching tests were carried out with sodium thiosulfate, glycine and sodium thiosulfate-glycine to compare the efficiency and stability of extractants in the recovery of gold and silver.
Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and …
The leaching behavior of gold from an oxide gold ore using copper–tartrate–thiosulfate solutions has been investigated. Experimental parameters, including temperature, initial pH, and concentrations of copper tartrate and thiosulfate, were systematically studied. The capability of gold leaching using …
The results show that copper in its thiosulfate complex can be substituted by mercury via Lewis substitution and cuprous sulfide was formed on the surface of leaching residue. The kinetics of mercuric sulfide leaching with cuprous-thiosulfate solutions was controlled by the product layer diffusion.
The thiosulfate leaching process it catalysed by copper and has several advantages over the conventional cyanidation process. Thiosulfate leaching can be considered a non-toxic process, the gold dissolution rates can be faster than conventional cyanidation and, due to the decreased interference of foreign cations, high gold …
This study provides a new idea and material preparation method for highly efficient, selective, and large-capacity recovery of Au (I) from thiosulfate leaching solution.
This article presents a detailed kinetic study of gold leaching in cyanide, ammonia/thiosulfate, and chloride/hypochlorite solutions.
Thiosulfate leaching is a promising alternative to cyanidation, and the main hindrances for its wide commercial application are the high thiosulfate consumption and the difficult recovery of dissolved gold. In this review, the four solutions to reduce the consumption of thiosulfate, including the control of reaction conditions, the use of additives, the …
Thiosulfate leaching has been regarded as a promising alternative to cyanidation, but it still faces the challenge of the recovery of low content of gold from …
The addition of copper and citrate in thiosulfate solutions can accelerate gold dissolution rate by about an order of magnitude. For the copper-citrate-thiosulfate system, thiosulfate ion works as the complexing agent for aurous ion, and it is extremely critical to the gold leaching process.
The recovery of gold using thiosulfate was first proposed early in the 1900s. In the Von Patera process, gold and silver ores were subjected to a chlorination roasting followed …
The aim of this work was to develop a hydrometallurgical (or wet) technique to convert elemental mercury to stable compounds by 1) dissolving mercury in aqueous hypochlorite media, and 2) precipitating mercury as mercury sulfide or mercury selenide through controlled reaction with aqueous thiosulfate or selenosulfate ion. Different …
