Relations between the Natural Characteristics of Gold and the Treatment Methods

The natural presentation of gold largely presides in the election of a process of treatment, favoring or stopping more or less the use of some of the physical or chemical properties previously mentioned.

The natural characteristics of the gold or of its minerals which are carriers which are held in consideration for their treatment are mainly their pelletmetry and its associations with the gangue minerals.

The efficiency of the gravimetric methods is limited by the inferior particles in a 60% of UM.

This dimension perhaps limits more, frequently modifying the form of the particles of gold to recuperate: grams, beads, filaments.

On the other hand and with this limitation, the flotation and the Cyanidation remain as the only methods of treatment available.

As with all the other minerals, the flotation demands a pretty complete liberation of the element to recover.

The grinding will be, another amount, better taken than the dimension of the gold nuggets, which is light, unless one is not content, in the case where the gold is extremely fine, with the flotation of the minerals which are carriers of gold (sulphurs in general).

In a similar dimension of the particles of gold, the Cyanidation demands in general a grinding less elevated than the flotation, due to the fact that it is not necessary that the gold be liberated completely but instead only turned accessible to the solution of attack.

In the operations of the grinding, another property of gold intervenes: the ductility.

The gross grains of gold due to this ductibility are grinded very difficultly and are likely to have the tendency to crush and flatten and after to incrustrate particles of gangue, one combats this inconvenience by recovering the gross gold by gravimeters from its mineral liberation.

Finally, the nature of the association of gold with the minerals of the gangue intervenes with the applicability of the methods of treatment, influencing noticeably above its mineral liberation.

The gold, for example, can be included in the minerals which are carriers, or in the fissures or in the unions of the nuggets.

The accessibility of the gold to the cyanide or its method of mineral liberation or it will be the same in each case.

The type of mineral association and the dimension of gold can be combined to give multiple natural presentations of the precious metal, whether it is that it shows the major part of the time under the form of natural gold.

Thus, it is possible for the gold to be finely included in the sulphurs, whether it be in a submicroscopic dimensions, presenting it mixed between more than ten microns in the sulphurs or in quartz.

The treatment of these minerals will be completely different:

• The first will not be treated by direct Cyanidation and will need a supplementary operation to liberate the gold;
• The second can be treated directly by grinding and Cyanidation.

You will finally note that even though these simple cases exist, frequently the gold is presented naturally with the dimensions and the associations different to the interior of one same mineral.

This complexity of presentation drags an even larger complexity of treatment.