Gold Minerals Treatments

Gold is an element which is not very reactive and gives place to a pretty limited number of natural compounds.

In the different types of minerals found, it is frequently presented under the form of natural gold or under the form of cloths of gold and silver.

Gold can be presented free or associated to other mineral phases, sulphurs in particular; its dimensions can reach from the centimeter to the micrometer. The unit of the mineralogy of gold, as well as some of its more characteristic properties (very elevated density, humidity by mercury, natural floatability, solubility in the solutions of cyanide) conduce to the development of four great techniques of treatment which well can be placed into action in diverse manners; and are recognized in all the processes of recuperation of gold in the world.

Gravimetrical Treatment, Amalgamation, Flotation and Cyanidation

These techniques, as well as some other procedures of preparation (chemical oxidizing, caging (toasting) of the sulphuric concentrates, etc.), are described, the possibilities and the limits of its application are shown.

Mineralogy of gold, of the gangue of the associated sulphurs, dimension of the gold, etc.

In all times, the gold has become the interest of men which have used this metal with monetary purposes or of decoration principally.

Gold is in effect one of the oldest metals known and exploited. Its rarity and its inalterability have made of it a searched substance whose price, in relation to other mineral substances, have always been relatively elevated.

Until 1968, its price was fixed in US$35.00 per ounce. The regular increase of the costs of production determined, then, the interest for its exploitation and conducted little by little to the closing of some mines and the diminishing of the prospecting and the mineralogical investigation.

In effect, from the publication in 1950, the work of Dorr and Bosqui (1) Cyanidation Concentration of Gold and Silver Ores, no other work of this importance has reappeared.

In the French plain, R. Hquot (2) mentioned the point above the treatment of precious metals in 1969.

In 1968, the price of gold got to be free and from then on has not ceased to progress regularly, despite some fluctuations.

A new interest for the yellow metal has been manifested now, due to the increase of the prospecting, the opening and re-opening of new mines for the growth of the investigations about the procedures of treatment, both old and new.

Whether or not the lixiviation by cyanide will always be the base procedure for the treatment of the minerals of gold, new techniques have appeared, others are slowly but surely being abandoned, the new procedures and reactive are appearing.

One synthetic exposition of the techniques being used in the mineralogy of gold appears nowadays, consequently being very useful. Such is the purpose of making this article, limiting us basically to the treatment of the minerals in which the gold represents the main recoverable value.

We can not, nonetheless, forget that one important part of the gold produced in the world comes from the treatment of concentrates of base metals, from which one can recuperate them as a sub product (40% of the production of The United States).

The general principles exposed in the first part will be illustrated immediately by the description of the schemes of industrial treatment.