ENHANCED PRESSURE DISSOLUTION OF ENARGITE USING PYRITE OR FERROUS SULFATE

Enargite (CU(3)ASS(4)) is hard to leach mineral in acid media, which requires high oxygen overpressures and high temperatures for fast dissolution rates. To improve the leaching kinetics of enargite in milder conditions, additions of pyrite or ferrous sulfate has been proposed. In this research, mixtures of enargite/pyrite, with 10 to 50 weight percent of pyrite, were leached in H2SO4-O-2 media, while pure enargite was leached in H2SO4-O-2 and H2SO4-FeSO4-O-2 media. The results showed that mixtures of enargite/pyrite leached faster than pure enargite and the rate enhancement increased with higher pyrite content. For a mixture with 50% pyrite, size 46 mu m complete dissolution could be obtained in 20 min at 180 degrees C and 690 kPa PO2. In the same conditions, the dissolution of pure enargite was less than 15 %. Similarly, adding FeSO4 to the leaching solution augmented the enargite leaching rate and again the rate enhancement increased with larger additions.