Leaching Kinetics of Chalcopyrite Concentrate by Ionic Liquids

Ionic liquids as green solvents with high thermal stability, recyclability, low flash point, and low vapor pressure, have been considered as a viable alternative in hydrometallurgical processes. In this study the leaching kinetics of chalcopyrite concentrate was investigated using 1-Butyl-3-methylimidazolium hydrogen sulfate (BmimHSO(4)) as an acidic ionic liquid. The Effect of operational parameters, including temperature, BmimHSO(4) concentration, H2O2 concentration, stirring speed, solid-to-liquid ratio, and particle size on the rate of copper dissolution of CuFeS2 were examined systematically. The highest Cu efficiency (ca. 97%) was achieved using 40% (w/v) BmimHSO(4), 30 %v/v H2O2, and 10 g.L-1 solid to liquid ratio for particle sizes less than 37 mu m at 300 rpm and 45 degrees C after 180 min leaching time. Kinetics study using Shrinking Core Model (SCM) revealed that CuFeS2 leaching process using BmimHSO(4) follows chemical reaction-controlled process. Under these circumstances, the calculated activation energy was 46.66 KJ/mol. Moreover, the orders of reaction with respect to BmimHSO(4) and H2O2 concentration, solid to liquid ratio and particle size were estimated to be 0.539, 0.933, -0.676 and -1.101 respectively. The obtained Arrhenius constant was found to be 0.26 x 10(6). The calculation of apparent activation energy using "time given to a fraction method" revealed that the leaching mechanism remains the same over the course of time.