A new method to improve the CO2 capture performance of carbide slag during the cyclic calcination/carbonation process by adding HCl intermittently(indirect chlorination) was proposed in this work. The effects of intermittent addition of HCl on the cyclic carbonation characteristics of carbide slag under different reaction conditions such as cycle number when HCl was added

carbonation temperature and volume ratio of CO2/HCl were investigated in a dual fixed-bed reactor by adding HCl into carbonation atmosphere. The results showed that the CO2 capture performance of carbide slag during the cyclic calcination/carbonation process can be improved by adding HCl intermittently during the carbonation. The optimum CO2 capture performance of carbide slag was achieved when HCl was only added during the first 4 cycles and the CO2 capture capacity after 10 cycles was 51% higher than that without addition of HCl. Chlorination happened between HCl and CaCO3

which decreased CO2 diffusion resistance through the compact product layer of CaCO3

and thus higher carbonation conversion was obtained. The optimum carbonation temperature was still 700℃ in the presence of HCl. As the volume ratio of CO2/HCl increased

the positive effect of HCl on the CO2 capture performance of carbide slag decreased.