Arsenic & Antimony Minerals

As the previous ones, with the exception of the mispickel, these minerals are more or less soluble in the solutions of cyanide, thus adding the consumptions of reactive and oxygen.

But besides, this dissolution has as an effect to make the kinetic of extraction of the gold slower and of reinstituting the partially refractory mineral to the Cyanidation.

This inhibition finds its origin not only in the depletion of the oxygen of the solution, instead above all in the formation of a performance in the surface of the nuggets of gold, resultant of the precipitation of the products of attack of the arsenic and of the antimonies.

Another inconvenient of the presence of the arsenic in the solution appears with the precipitation of gold above the dust of zinc. One part of the arsenic is once again found in the cement, but above all it gives to it the formation of the AsH3, very toxic gas which needs a very careful ventilation of the installation.

The association of gold-mispickel is a very interesting case.

Gold in this case is in frequent effect, including under submicroscopic forms and not directly cyanidable.

In the presence of the arsenic or of the antimonies, the gold is in general concentrated by flotation and the concentrate is burned. The burning allows, on one part, to liberate the gold in an upward direction of the Cyanidation and of another, eliminate the arsenic and a large part of the antimonies.

A careful control of the temperature and of the aeration of the oven must be maintained above all in the presence of the antimonies to avoid the partial fusion of this metal, which can after cover the particles of gold again.