2009 Volume 125 Issue 3 Pages 115-120
The chemical leaching of chalcopyrite was carried out to investigate the effects of temperature, ferrous ions and pH values on the leaching rate. The copper extraction of chalcopyrite attained 94% after 11 days when the initial pH value was 0.7 and the extraction temperature was 60 centigrade, while it was under 5% at pH 2.0. If the temperature was over 40 centigrade containing sufficient sulfuric acid, the passivation was not taken place which indicates increasing in the reaction temperature is one of the efficient ways to prevent from passivation occurrence. When the ferrous ions with the amount of 1.8 g/l was added (as initial) , the copper extraction was 93% after 5days at pH 0.7 and 60 centigrade. The extraction rate was faster by 2.6 times than the case of the extraction without ferrous ions. This is considered that high concentration of ferric ions oxidized from ferrous ions by dissolved oxygen worked as an oxidant for concentrate leaching. However, the high concentration of ferric ions seems to be an inhibitor for chalcopyrite chemical leaching when both initial pH and the temperature are low. When the pH value was controlled constantly, the higher dissolution rate was obtained at the lower pH range at over 40 centigrade. This shows sulfuric acid concentration plays a significant role in the chemical leaching of chalcopyrite. Moreover, when the temperature is less than 30 centigrade, passivation was taken place at pH controlled below 1.0; passivation occurs easier in the higher range of initial sulfuric acid concentration. Concerning passivation, some more research is necessary. We also examined leaching behavior of several kinds of chalcopyrite concentrates. The IOCG chalcopyrite leaching behavior seems to be similar with our leaching results mentioned right above but we found that there was a difference like leaching rate .This is considered that iron minerals were contained as impure compounds in respective chalcopyrite samples.
