Chalcopyrite dissolution rate laws

Meta-analysis of 173 rate measurements from 21 publications was used to develop rate laws for chalcopyrite dissolution under environmentally relevant conditions. Multiple linear regression analysis of 28 data for nonoxidative chalcopyrite dissolution in the presence of O₂ and Cl^- produced the following rate law:r=10-1.52e-28200/RT[H+]1.68Here, r is the rate of chalcopyrite dissolution in units of molm^-2s^-1 where the surface area is expressed on a geometric basis. Multiple linear regression analysis of 36 data for chalcopyrite dissolution caused by reaction with Fe(III) in the presence and absence of O₂ and Cl^- produced the following rate law:r=101.88e-48100/RT[H+]0.8[Fe(III)]0.42Some data were excluded from these rate law models because they were inconsistent with the overall dataset and/or were relatively unconstrained. There were no published rate data that could be clearly identified as representing chalcopyrite dissolution caused by O₂ oxidation alone. Although there are numerous reports that suggest that chalcopyrite dissolution rates are increased by the presence of Cl^- in solution, the regression models documented that the effect of Cl^- on dissolution was insignificant for this dataset. The rate laws developed in this work are most appropriate for characterizing chalcopyrite dissolution at low pH (3), and will ultimately allow better modeling of acid, sulfate, Fe, and Cu release to the environment.