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
This keeps the leach sample secure prior to its assaying. A simple electric box, lock and key, piece of pipe, funnel, bottle and yes, some wire.
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
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:
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
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
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:
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
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
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