Enargite oxidative dissolution: Preliminary data of flow-through experiments

The oxidative dissolution of enargite, Cu3AsS4, was studied in a flow-through experiment at pH 1 and 4. Preliminary data indicate, at both pH, a moderate rate of dissolution (in the order of 10(-10) to 10(-9) mol.m(-2) s(-1)), with a faster release of Cu with respect to As. This behaviour may partly explain the high Cu/As ratios typical of waters draining enargite-rich deposits. The estimated activation energies depend on "reaction histories", being lower (35 +/- 8 to 48 +/- 8 KJ/mol) for previously reacted fragments than for newly reacted fragments (similar to 60 +/- 8 KJ/mol). These last values are consistent with literature data.