Cyanide Leaching

Cyanide Destruction Hypochlorite / Chlorine

In the Cyanide Destruction by Hypochlorite reaction, the pH has a strong inverse effect on the ORP. Thus, wastewater treatment facilities must closely control the pH to achieve consistent ORP control, especially if they use hypochlorite as the oxidizing agent. Adding hypochlorite raises the pH, which, if unchecked, lowers the ORP. calling for additional hypochlorite. Controlling the pH at a setting above the pH level where hypochlorite has an influence and separating the ORP…

Alkaline Chlorine-Hypochlorite Oxidation: Chlorine was used for cyanide destruction in the early

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By | 2017-03-19T08:37:04+00:00 March 13th, 2017|Categories: Cyanide Leaching, Reagents and Chemicals|Comments Off on Cyanide Destruction Hypochlorite / Chlorine

Organic Carbon TOC Pre-Flotation & Preg‐Robbing of Gold

Organic carbon is a common problem for base metal production and precious metal leaching. In froth flotation, liberated organic carbon is naturally hydrophobic and will be recovered with the other minerals, lowering the grade of the concentrates. It can also adsorb collectors and frothers, reducing the efficiency of the mineral recovery process. In leaching, the absorption properties can remove precious metals from solution before the metals are extracted by the intended process adsorption routes.

To determine if the organic carbon would cause problems with gold adsorption or “preg

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By | 2017-03-17T19:13:59+00:00 November 5th, 2016|Categories: Cyanide Leaching|Comments Off on Organic Carbon TOC Pre-Flotation & Preg‐Robbing of Gold

Methods of Testing Cyanide Solutions

The method given above is difficult to apply when solutions containing soluble cyanides of zinc and other metals require to be titrated. “ A white flocculent precipitate occurs at a certain stage, probably consisting of simple (insoluble) cyanide of zinc, formed by decomposition of the soluble double cyanide:

K2ZnCy4 + AgNO3 = KAgCy2 + ZnCy2 + KNO3

This precipitation occurs long before the whole amount of potassium has been converted into the soluble double salt of silver (KAgCy2), for the solution after the appearance of the flocculent precipitate, still gives the Prussian blue precipitate

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By | 2017-03-18T10:12:28+00:00 November 2nd, 2016|Categories: Cyanide Leaching, Gold Extraction, Laboratory Procedures|Comments Off on Methods of Testing Cyanide Solutions

Potassium Cyanide Chemistry on Minerals & Metals

The ordinary gangue of most ores (silica and silicates of the alkalies and alkaline earths) exercises no direct influence on the cyanide solution. The carbonates of the alkaline earths are also probably without influence. The decomposing effects of sulphides of the heavy metals vary with the physical state of the sulphides.

Metallurgists found that dilute cyanide solutions exercise a “ selective action ” in dissolving gold and silver in whatever form they may be present, in preference to sulphides or other salts of the base metals. There are exceptions to this rule, some of which are noted

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By | 2017-03-18T10:16:50+00:00 November 2nd, 2016|Categories: Cyanide Leaching|Comments Off on Potassium Cyanide Chemistry on Minerals & Metals

Increase Potassium Cyanide Leaching Reaction with Gold & Mercury

These methods are described here for convenience, as being more intelligible after the chemistry of the process has been discussed. The necessity of the presence of oxygen has already been dwelt on above. It has, however, been frequently pointed out that in the interior of a mass of ore undergoing treatment the conditions are not favourable for the maintenance of a sufficient quantity of oxygen in a free state. Both the cyanides and the pyrites of the ore tend to unite with it, and further absorption of free oxygen from the air is extremely slow. Hence the time required for the treatment of

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By | 2017-03-18T10:18:12+00:00 November 2nd, 2016|Categories: Cyanide Leaching|Comments Off on Increase Potassium Cyanide Leaching Reaction with Gold & Mercury

Oxidised Pyrite Leaching by Potassium Cyanide

When the pyrites occur in tailings which have been subjected to the action of the weather for some time before treatment, compounds are formed which are more prejudicial to the solution than the sulphides. Sulphide of iron, FeS2, is oxidised by air and water, ferrous sulphate and free sulphuric acid being formed, thus:

FeS2 + H2O + 70 = FeSO4 + H2SO4

The protosulphate suffers further oxidation, and normal ferric sulphate (Fe2 . 3SO4) is produced, which eventually loses acid and becomes a soluble basic sulphate, Fe2O3 . 2SO3. Other basic salts of complex and unknown compositions appear to be formed

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By | 2017-03-18T10:19:21+00:00 November 2nd, 2016|Categories: Cyanide Leaching|Comments Off on Oxidised Pyrite Leaching by Potassium Cyanide

Effect of Potassium Cyanide on Gold & Metals

The discovery that metallic gold is soluble in potassium cyanide came after studying the action of cyanides on plates of gold, and announced that they were slowly dissolved. Metallurgists pointed out that gold-leaf is dissolved by a dilute solution of the salt, and also showed that if the gold floats on the surface of the liquid, so that one side of the leaf is in contact with the air, while the other is bathed by the solvent, the action is much more rapid than if the metal is completely submerged. Elsner had previously furnished some evidence that the presence of oxygen is required for the

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By | 2017-03-18T10:21:59+00:00 November 2nd, 2016|Categories: Cyanide Leaching|Comments Off on Effect of Potassium Cyanide on Gold & Metals

Gold Vat Leaching

Gold Leaching done in round vats, constructed of wood, concrete, or iron and steel. If wood is used it is covered by a coating of paraffin paint, or by a mixture of asphaltum and coal-tar. Concrete and brick vats are not now advocated owing to their great cost and less convenient working, and wooden vats suffer more than iron and steel ones from exposure and from being alternately emptied and filled. Iron leaching vats are not usually coated inside, as little if any action goes on between the metal and cyanide solutions; occasionally

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By | 2017-03-17T19:14:40+00:00 November 2nd, 2016|Categories: Cyanide Leaching|Comments Off on Gold Vat Leaching

How to Prepare and Storage of Cyanide Solution

The cyanide is usually dissolved in a little water before being added to the stock solution, as the amount of KCy present is more easily determined in a strong solution than in any other form. A special dissolving vat of small size is often provided and is placed at a higher level than the large vats used for the storage of the stock solution. High grade cyanide is now largely used containing 98 to 99 per cent, of KCy. Sodium cyanide is also used, and this, calculated as potassium cyanide, contains 125 to 130 per cent, of available KCy. The contents of these boxes are broken into lumps and

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By | 2017-03-17T19:14:41+00:00 November 2nd, 2016|Categories: Cyanide Leaching, Reagents and Chemicals|Comments Off on How to Prepare and Storage of Cyanide Solution