The Toasting of Auriferous Arsenopyrrites in the Recuperation of Gold

Finalizing the mounting of the Pilot Plant of Toasting and after some tests of adjustment and heating, on may 11^th of 1990, a march with loading of such a plant began, conjugating it with the interest of the Mining Negociation and experts with such a purpose were found in a certain developing country.

It is a fact gthat the Pilot Plant of Toasting opens great possibilities to investigate and study many problems of the mining industry. For example, the presence of As and Sb in the copper concentrates of the mining areas of the north and center of the country with concentrations of up to 10% of As, limit dramatically their exploitation for rreasons of markets, economical punishments, the lack of ingredients and a lowering of prices, besides, the present reality demands a change in the productive scheme which is oriented to the obtaining of refined metals and of products with higher added cost; having in mind too that the mineral resources due to not being renewable must reach the highest extraction of the values contained.

The problem with the arsenical copper motivated and sustained the actions of the INCITEMI and later on of the INGEMMET to look for the technology which would eliminate the As of its minerals and/or concentrates; including for this different fields of the metallurgy such as: the hydrometalurgical processes in cold, hot and high precision; bacterial lixiviation and pyrometallurgic processes. Being in our judgement, for the moment, the most viable the process of toasting.

The Pilot Plant of Toasting allows, also, to investigate other problems of interest for the mining industry. With this purpose the INGEMMET has programmed to develop the following studies:

• Toasting of auriferous arsenopyrrite and pyrrite.
• Sulphate toasting of copper concentrates.
• Toasting of molibdentie.
• Chlorurant toasting of residues of refineries.
• Production and regeneration of active carbon.

In the present event, where different topics will be analyzed concerning metallurgy, the INGEMMET presents to you the result which it has reached through the pyro hydrometallurgical study of auriferous pyrrites and arsenopyrrites, being the most important processes the toasting, for the elimination of the arsenic-antimonious and sulphur, followed by the cyanidation for the extraction of the valuable metals: Au Ag.