LEACHING OF AN AURIFEROUS SULFIDE CONCENT RATE BY IN-SITU ELECTROGENERATED BROMINE AND RECOVERY OF COPPER BY LIQUID-LIQUID-EXTRACTION

The leaching of a sulphidic concentrate containing enargite (Cu3AsS4), pyrite (FeS2) and covellite (CuS) can be achived by in situ electroge nerated bromine. Among the three preceding constituents, only pyrite a ppears to be significantly refractory. Such a behaviour of pyrite caus es no major problem as copper is only present in enargite and covellit e which are easily leached by bromine and as the release of gold and s ilver also present in the sulphidic concentrate does not require the c omplete dissolution of pyrite. The bromide ions have almost no tendenc y to form bromide complexes with copper(II) and iron(III) and thus do not interfere with the extraction of copper by classical reagents such as LIX 984N. This reagent was found to be highly selective for copper (II), especially with silver(I) and gold(III) which are engaged in str ong anionic bromide complexes.