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gold from the leach solution is presented and discussed. CIP or CIL and Merill Crowe processes are the standard gold recovery process in ) It was reported that aurous thiosulfate complex has no afnity to activated ) Therefore, CIP or CIL processes is not applicable in the ammonium thiosulfate leaching process.
In thiosulfate gold leaching, Cu2+ ions are commonly used as oxidizing agents, while the thiosulfate ion acts as a ligand forming a soluble gold thiosulfateammonia complex (Aylmore and Muir, 2001). It was suggested that gold leaching in the absence of Cu2+ ions, with an external current acting as a oxidizer, is not possible
leaching of gold as its absence makes gold passive by the build up of sulphur coating on the surface as a result of decomposition of thiosulphate. It is known that thiosulphate is a metastable species that readily undergoes decomposition in aqueous solutions.
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 cations, high gold recoveries can be obtained from the thiosulfate leaching of complex and carbonaceoustype ores. In addition, thiosulfate can be cheaper than cyanide.
Using nickel as a catalyst in ammonium thiosulfate leaching for gold . extraction. Mater. T rans. 2004, 45, 516526. 45.
#0183;#32;In conclusion, ammonium thiosulfate leaching for gold recovery preferably should be performed at: low thiosulfate concentrations, ranging from to M; an ammonia to thiosulfate ratio of 12; copper concentrations ranging from 50 to 100 ppm; an alkaline pH, preferably 910; ambient temperature to 50 #176;C.
Before leaching the gold, ore must be crushed and grinded into small particles, usually particle size varies between 30 and 180 m. Free milling ores are ready for leaching after crushing and grinding whereas refractory ores need pretreatment. It is important to pretreat a refractory ore before leaching to achieve better gold extraction.
and greater efficiency with gold deposits associated with pregrobbing ores. The thiosulphate leaching process, followed by resininpulp gold extraction, has been developed by SGS to the point where it is a technically and economically viable alternative to cyanidation for some gold bearing ore bodies. Whether the leaching is performed in
Copper catalyzed ammonium thiosulfate leaching process has been proposed as an alternative gold extraction process to cyanidation. In order to recover gold from the ammonium thiosulfate solution, ion exchange process has been proposed as a gold recovery
The application of ammonium thiosulfate for the treatment of coppergold ores has been investigated. Leaching studies were conducted with copper minerals, copper minerals with gold addition to solution and coppergold samples of different copper and gold grades. The behaviour of thiosulfate, tetrathionate and sulfate in solution was studied using ion chromatography. The copper sulfide
By increasing 48 mm copper sulfate, a 30% increase in gold extraction can be expected, and its catalytic role in ammonium thiosulfate can be recognized,Abdolli, et al. To dissolve the gold in the copper anode sludge screened process, it was leached into aqua regia, and more than 99 % of the gold solution entered aqueous phase together with impurities.
The present work deals with the recovery of gold using ammonium thiosulfate as a leaching agent from waste mobile PCBs containing % Au, % Ag, % Cu, % Ca, % Al, % Sn,
Keywords: gold leaching, ammonium thiosulfate, chloride, thiourea, thiocyanate Introduction The most common hydrometallurgical methods of primary raw material utilization in the production of gold are based on the use of cyanide (Hilson, 2006). In this method a weak sodium cyanide solution (NaCN) of 100500 ppm is used. Since the Baia Mare
Thiosulfate leaching offers a number of benefits related to gold recovery yields and environmental concerns: 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.
#0183;#32;Leaching of the metals from PCBs was investigated with varying solidtoliquid ratio in ammonium thiosulfate solution. As illustrated in Fig. 3, the increase in solidtoliquid ratio from g to 1 g/10 ml resulted in the decrease of metal the maximum solidtoliquid ratio in the present study (, 1 g/10 ml), Au extraction was lt;5% due mainly to the lack of leaching reagent as
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