thiosulphate leach solution onto copper metal powder, or some other reductant, following separation of solids and liquids in the leach slurry by filtration or counter current decantation. Use of the resin-in-pulp method is limited to those deposits requiring mild thiosulphate leaching conditions, since strong thiosulphate leach conditions result
In the thiosulphate leaching system oxygen is thought to be consumed in the hodic process, that is the re-generation of the Cu NH 3 4 2 . In leaching experiments copper was always added in excess. A copper concentration of 6 mM is sufficient to oxidise about 1200 mg/L of gold.
The role of oxygen in thiosulphate leaching of gold has been investigated in both pure gold and ore systems. The gold dissolution decreased in the presence of oxygen in the pure gold system. Air or oxygen bubbling caused higher consumption of thiosulphate and leaching passivation.
In the presence of Cu and O 2 , the leaching percentage increased by almost 30%. Xiong Tong et al. 36 researched the role of oxygen and ammonium ions on the silver leaching in thiosulfate ...
leaching experiments were conducted at 25 oC and the leaching time was 6 hours. Figures 1 and 2 show the changes in Ag and Cu leaching recovery during the leaching process at various thiosulphate concentrations. Fig. 1. Effect of thiosulfate ions concentration on Ag recovery; s/l = 1:10, initial NH 3 concentration 0.6 mol/dm3, temperature 25 oC ...
Oxygen Due to the typically large solution volumes of low gold concentration thiosulfate leach solutions, ion exchange resin or other suitable adsorbent is required to recover and concentrate the gold. For high concentration gold thiosulfate solutions e.g. leaching of gravity concentrates , sulfide precipitation
A process based on thiosulphate leaching, followed by resin-in-pulp gold extraction, has been developed to treat . the carbonaceous, preg-robbing ores of Barrick’s Goldstrike orebody in the Carlin Trend of Nevada, USA. These ores have proven to be amenable to thiosulphate leaching, under mild conditions; gold leaches rapidly as the gold
An improved thiosulphate leach process for the recovery of gold from ores and other gold-bearing materials, characterised in that the leach solution comprises thiosulphate, thiourea or a reagent chemically related thereto, and an oxidant that does not oxidise thiosulphate, the process producing a pregnant leach solution from which gold may be recovered.
3 IUPAC-recommended spelling; sometimes thiosulphate in British English is an oxyanion of sulfur. The prefix thio-indi es that the thiosulfate ion is a sulfate ion with one oxygen replaced by sulfur. Thiosulfate has a tetrahedral molecular shape with C 3v symmetry. Thiosulfate occurs naturally and is produced by certain biochemical processes.
In recent years thiourea and thiosulphate leaching gained a certain attractivity because it was believed that less toxic or non-toxic reagents are involved. An additional argument for thiourea or thiosulphate are their high leaching rates that can reach 250mg/cm2 per hour exceeding cyanides almost by a factor of 100. The technical ...
The thiosulphate leaching of gold ores has great potential to reduce the impact on the environment compared to the cyanidation process. Unlike cyanide, which is highly toxic, the chemicals used in the thiosulphate leaching process are benign, and there is great potential to apply the technology in those jurisdictions of the world ...
alternative to cyanidation for some gold bearing ore bodies. Whether the leaching is performed in stirred tank reactors or heaps, the size and type of equipment needed for a thiosulphate leaching flowsheet is very similar to a conventional cyanide leach. SGS is a global technical leader in the field of thiosulphate leaching, and our
The processing of gold is becoming more compli ed due to the increasingly complex nature of the remaining gold-bearing ore bodies. This worldwide phenomenon is the driving force for the development of alternative technologies for the leaching and recovery of gold from so-called double refractory ores. Barrick Gold recently commercialized a unique calcium thiosulfate leaching plant to treat ...
The next process of gold extraction from Hydrometallurgy route is Leaching. There are reagents that can be used to gold leaching process: Mercury Hg , Cyanide CN- usual as KCN or NaCN, Thiosulphate Na2S2O3 , and Thiourea. Reagent vote for leaching process depend on: 1. Kind of Ore 2. Grade of Gold in the Ore 3. Cost 4. Material Handling 5.
leaching flowsheet. Figure 3. Copper chloride leach process. Leaching Chemistry As outlined earlier, the leaching chemistry that takes place within a total POX autoclave is very complex and will vary from case to case according to the mineralogy of the concentrate fed to the autoclave.
Valentin Ibarra-Galvan, Alejandro López-Valdivieso, Xiong T., Yi-Qi C., 2014. Role of oxygen and ammonium ions in silver leaching with thiosulphate–ammonia–cupric ions. Rare Metals 33, 225–229. Vazarlis, H. G., 1987. Hydrochloric acid-hydrogen peroxide leaching and metal recovery from a Greek zinc-lead bulk sulphide concentrate.
