4. Conclusion
During sulfate roasting, copper extraction is mainly affected by roasting temperature, roasting time and Na2SO3
addition amount. The optimum roasting temperature and time were 500˚C - 550˚C and 2 h, respectively. At the
optimum conditions, there was about 96% of copper leached out. The sulfation promoter Na2SO3 only improved
the copper extraction at high roasting temperature. It couldn’t improve the sulfation effect when the roasting
temperature was below 550˚C.