Effect of Roasting Temperature for Copper Leaching of Sulfide Concentrate by Combined Methods

This study was undertaken to develop a cost-effective method of copper leaching in sulfide concentrate involving minerals as chalcopyrite and pyrite. The combined methods involving low temperature roasting of sulfide copper minerals with potassium chlorides without the formation of sulfurous gases and their evolution into the atmosphere is suggested. The effect of experimental parameters such as a roasting temperature and time has been presented and discussed in detail. This study was carried out in the roasting temperature range 400˚C - 600˚C and roasting time ranges 1 - 4 h with potassium chloride. The obtained cake is leached by an aqueous sulfuric acid 60 g/l concentrated at pH = 2 - 2.5 and 4 h. The concentrate, a roasting cake and after leaching solid residue were analyzed by chemical analysis, XRD and SEM-EDX. At temperature ranges 450˚C - 550˚C and 3 h of roasting, the process is activated. The recovery of copper into the solution at optimal roasting condition (500˚C, roasting time 3 h) is 93.2%. The advantage of the developed method is that, it not requires high roasting temperature and the use of autoclave for leaching. The method gives possibility to leach the concentrate at room temperature and atmospheric pressure, which gives possibility to reduce cost of the process.