sodium hypochlorite used in cyanide leaching of gold

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The reactions between gold and hypochlorite leach solutions containing hydrochloric acid and sodium chloride are demonstrated below 4Au 16NaOCl 10H2O → 4HAuCl4

Jun 01 2007 · An oxide gold ore was subjected to chloridehypochlorite leaching at room temperature The effects of three factors including CaOCl 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

In this research oxidation of sulfide minerals and leaching of gold from a gold bearing sulfide concentrate using chloride hypochlorite solution was investigated The effects of calcium

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 mgcm2hr which is 10 50 times the rate of gold dissolution in a cyanide solution Fig 1 30 vVv 05 9 NaOCl 20 0 1 1 I I I

Jan 01 2016 · A prefeasibility test on hypochloriteleaching 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 bottleroll test work pH 65 Eh 114 V vs SHE 33 solids for 96h leaching time reagent consumption was 555 kgt NaOCl and 325 kgt HCl compared with 015 kgt NaCN and

Sodium hypochlorite pretreatment for heap leaching gold ore When the sodium hypochlorite pretreatment was followed by cyanidation greater than 85 per cent gold extractions were achieved Gold extraction was shown to be dependent on sodium hypochlorite concentration heap leach flowrate temperature and leaching time or bed volumes

Apr 24 2017 · Bleach is the chemical compound sodium hypochlorite When combined with hydrochloric acid the mixture produces chlorine that dissolves gold from gold ore This was the first commercial method used for gold extraction Place the ore into the mortar and grind it to the size of sand grains

Chlorine was the first commercial gold extracting agent In the late 1800’s it was introduced on the market as ” DuPont Mining Salts” Although I have no direct proof I’m sure that this was nothing more than sodium hypochlorite the stuff that Clorox is made from

The hydrometallurgical leaching of native gold from goldbearing 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

The major gold plating process is also that using cyanide plating solution in which gold is recovered by the same processes In these processes after the recovery of gold spent cyanide solutions are discharged into environment after the decomposition of cyanide using sodium hypochlorite for example as mentioned in the preceding section

This method fell into disfavor with the discovery that cyanide extraction was cheaper and easier for the untrained miner to use The usefulness of various extraction techniques for the production of gold is attested to by the fact that at the present more than 80 of the world’s gold production is obtained by chemical extraction

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

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 gL NaCl 1 HCl and 2 NaOCl nearly 90 of the gold was extracted in only 30 minutes

Figure 411 Chromatograms of the reaction of cyanide with sodium hypochlorite and ozone Figure 412 Degradation of cyanide in leaching by cyanidation Figure 413 Gold and silver extraction curve in cyanidation process Figure 414 Mass Balance of the process and was balance referent to the Gold Silver and CNbehavior

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

Leach solutions were prepared using deionizeddistilled water at the prescribed concentration of reagents Recovery of gold increased gradually to its maximum value of 9305 as the value of cyanide strength increased from 08 to 12 and the addition of sodium nitrite raise to 12 M No improvement for further addition of nitrites

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

The hydrometallurgical leaching of native gold from goldbearing 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

Apr 30 2018 · Cyanide has been used in the process of mining gold since 1887 When a dam burst at a gold mine in northwestern Romania in 2000 contaminated wastewater poured into tributaries of a major waterway in Hungary threatening the people animals and environment of Serbia Bulgaria and Romania

Although a twotank system is preferred complete cyanide oxidation to carbon dioxide and nitrogen can be accomplished in a singlestage unit provided close pH control is maintained ref 39 When sodium hypochlorite is used the reaction in the first stage is NaCN NaOCl NaCNO NaCl

leaching experiments the required reagents were added to a beaker containing deionized water all the reagents used such as sodium chloride calcium hypochlorite and sulfuric acid H 2 SO 4 were of analytical grade purchased from Merck Then the concentrate was added into the leachant solution in the beaker and stirred by a magnet

May 01 2001 · Gravity concentration followed by smelting was effective on some ores but not all Various experimenters learned that sodium hypochlorite sodium thiosulphate bromine and chlorine were effective leaching agents for some gold ores and the commercial use of these reagents was common by 1880