Ph Mineral Value

The pH used is generally comprehended between a natural pH and a value of 10, regulated by the sodium carbonate or the soda, the lime which depresses the gold and the pyrite is not generally used.

Finally, the sulphate of copper, the sulphur of sodium, the nitrate of lead, the dioxide of sulphur and the hiposulphite are used as activates.

The flotation of gold and of the accompanying sulphurs is a simple and economical operation; nevertheless, it needs to be known in narrow relation with the rest of the treatment.

When the cyanide intervenes, after the stage of flotation, the presence of the collectors and of other reactive can affect the putting into solution of the gold.

The collectors in particular, because of the layer that they form surrounding the nuggets or by the hydrofobicity which confer to them, slow down the action of the cyanide.

Besides, in the case in which the sollubilized gold is recuperated by the active carbon, the reactive of flotation can inhibit the absorption of the gold over the carbon. The losses in the soluble gold and a weak charge of carbon are the results of this.

A somewhat long stage of oxidation, a lifted regrinding of the concentrates or a burning, are necessary for producing the fluctuated concentrates correctly cyanidable.

When the flotation intervenes, after the Cyanidation, the presence of the ion CN can depress the sulphurs, the pyrite in particular. A destruction of the remaining cyanides by SO2 in acid pH allows remedying this inconvenient reactivating the sulphurs.

Another difficulty which is found in the flotation is in the presentation of the gold itself.

The dingy gold in the moldy surface does not float in effect, but difficultly. It can be activated by the sulphate of copper or a treatment of dioxide of sulphur.

Beyond the 250 microns approximately, the flotation of the gold is become difficult and needs the use of powerful collectors.

In the two cases, a gravimetric trap of gross gold will diminish these difficulties.

Finally, due to the weak fulfillment of the weight frequently found (1% and less); the operations of re-washing are delicate in its handling.

A revision of the equipment of flotation available presently in the market, have been recently performed by Young and Harris.