The dissolution of gold in dilute hypochlorite solution is very slow. With the addition of hydrochloric acid and sodium chloride to the hypochlorite solution, the gold dissolution rate will increase to 20 100 mg/cm2/hr, which is 10 50 times the rate of gold dissolution in a cyanide solution. Fig. 1 30 vV-v 0.5 9. NaOCl 20 0 1 1 I I I
The reactions between gold and hypochlorite leach solutions containing hydrochloric acid and sodium chloride are demonstrated below: 4Au + 16NaOCl + 10H2O → 4HAuCl4
The results of the gold leaching experiments showed that the best gold leaching parameters were obtained when the hydrochloric acid-sodium hypochlorite mix was at a ratio of 1 : 2, the added
An alternative non-cyanide lixiviant, namely sodium hypochlorite, has been used for the selective extraction of gold and silver from a copper concentrate. chloride–hypochlorite leaching of
Apr 24, 2017· Gold is an almost non-reactive metal, but halogens — chlorine, bromine, fluorine and iodine — can dissolve it. Chlorine is the cheapest and lightest product that can achieve this. Bleach is the stone compound sodium hypochlorite. When combined with hydrochloric acid, the mixture produces chlorine that dissolves gold from gold ore.
Sep 01, 2016· Gelatine has been used as a stabiliser for gold nanoparticles during the study of gold leaching in cyanide (McCarthy et al., 1998) and thiosulfate (Zhang et al., 2004, Zhang et al., 2008 Senanayake and Zhang, 2012) solutions to investigate the effect of concentration of the main reagents and background salts.
Because sodium hypochlorite is often used to treat cyanide in waste waters [70], hypochlorite easily oxidize cyanide. Therefore, competition experiments indicated that emission response of the
An oxide gold ore was subjected to chloride/hypochlorite leaching at room temperature. The effects of three factors, including Ca(OCl) 2 vs. NaOCl, OCl − concentration, and HCl concentration on gold leaching performance were investigated. Due to formation of CaOCl + complex in solution and hence less reactivity, calcium hypochlorite produces a sluggish gold leaching kinetics, taking twice
This research evaluated the kinetic control mechanism on the gold leaching with cyanide in alkaline media from a previously floated ore. a pre-treatment with sodium hypochlorite was carried
Jan 01, 2016· A prefeasibility test on hypochlorite-leaching McDonald Gold Mine oxide ore in Montana gave 68% gold recovery compared with 73% obtained with cyanide (McNulty, 2001). Under the conditions used in their bottle-roll test work (pH 6.5, Eh 1.14 V (vs. SHE)), 33% solids (for 96-h leaching time) reagent consumption was 5.55 kg/t NaOCl and 3.25 kg/t
Jun 01, 2007· Calcium hypochlorite produced a sluggish gold leaching kinetics, requiring twice more time (46 h) to achieve the maximum gold recovery of 58% compared to sodium hypochlorite. To have a reasonable gold leaching kinetics, it was found that OCl − in solution must be equal or higher than 10 g/L. The amount of HCl added and hence initial pH was
An oxide gold ore was subjected to chloride/hypochlorite leaching at room temperature. The effects of three factors, including Ca(OCl) 2 vs. NaOCl, OCl − concentration, and HCl concentration on gold leaching performance were investigated. Due to formation of CaOCl + complex in solution and hence less reactivity, calcium hypochlorite produces a sluggish gold leaching kinetics, taking twice
Dec 15, 2000· An alternative non-cyanide lixiviant, namely sodium hypochlorite, has been used for the selective extraction of gold and silver from a copper concentrate. Hypochlorite leaching of the as-received, as well as aqueous pressure-oxidized copper concentrate was carried out.
This research evaluated the kinetic control mechanism on the gold leaching with cyanide in alkaline media from a previously floated ore. a pre-treatment with sodium hypochlorite was carried
Calcium peroxide, sodium hypochlorite and sodium peroxide are all very stable and widely used multi-functional inorganic peroxides, and have the characteristics of long-term oxygen release. In the leaching pulp, oxygen can be slowly released for a long time, which is beneficial to increase the leaching rate of gold.
Sep 01, 2016· Gelatine has been used as a stabiliser for gold nanoparticles during the study of gold leaching in cyanide (McCarthy et al., 1998) and thiosulfate (Zhang et al., 2004, Zhang et al., 2008 Senanayake and Zhang, 2012) solutions to investigate the effect of concentration of the main reagents and background salts.
Leaching pure gold with an acidic sodium hypochlorite solution has been demonstrated to be effective. The initial rate of gold dissolution was extremely rapid. In a leaching solution containing 1 g/L NaCl, 1 % HCl and 2 % NaOCl, nearly 90 % of the gold was extracted in only 30 minutes.
Cyanide is destroyed by many naturally occurring chemicals as well as by oxidizing agents such as clorox. Cyanide is destroyed by sodium thiosulfate or sodium nitrite. An average fatal dose of HCN is about 50-60 milligrams. Cyanide dissolves both gold and silver from alkaline solution.
The reactions that take place during the dissolution of gold in cyanide solutions under normal conditions have been fairly definitely established. Most agree that the overall cyanide equation for leaching and cyanidation of gold is as follows: 4 Au + 8 NaCN + O2 + 2 H20 = 4 NaAu(CN)2 + 4 NaOH
THIOSULPHATE LEACHING AN ALTERNATIVE TO CYANIDATION IN GOLD PROCESSING ALTERNATIVES TO CYANIDE IN GOLD PROCESSING THIOSULPHATE LEACHING 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
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 100-500 ppm is used. Since the Baia Mare
The hydrometallurgical leaching of native gold from gold-bearing ores or the dissolution of gold metal during the recycling of electronic and precious metal scrap is performed every day using hazardous chemicals such as sodium cyanide or aqua regia. These chemicals represent health and safety risks for workers and a serious threat for the
Cyanide is highly toxic, so these cyanide wastewater must be treated professionally before discharging to avoid the environment pollution and damage to human and animal health. At present, the following are the commonly used cyanide wastewater treatment methods in gold cyanidation plants. 1.
Sep 01, 2019· But because sodium cyanide is so effective at dissolving gold, is well understood and relatively inexpensive, competing technologies need to offer compelling recoveries and economics to compete. “Cyanide leaching is very easy, robust and has simple chemistry,” says Rob Raponi, an independent metallurgical consultant specializing in gold
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