Influence of grinding time on the bioleaching of copper from copper slag

The present study aims to compare copper recovery from pulverized ground copper slag obtained from pyrometallurgical processing of copper. The method employed for copper leaching/recovery is a microbial catalyzed process with a solid% of 10% (w/v). Grinding/pulverization of the copper slag was carried out for a variable time period of 30, 60, 90 mins and the copper content in all the ground slag was 3.88% (w/w). Reason for varying grinding time was to allow liberation copper from the complex mineral matrix to enhance Cu leaching. 2.5 Liters batch bioreactor was used with one- Liter working volume for bioleaching of copper slag using the mixed culture of chemolithotrophic acidophilic iron and sulfur-oxidizing microorganisms. The Cu recovery from bioleaching of copper slag with a variable grinding time of 30, 60 and 90 mins was 77.8, 84.7 and 86.6% respectively. The recovery% obtained was highest with 90 mins but even 60 mins grinding time also resulted in an appreciable percentage of recovery.