Abstract: Carbide slag is a typical high calcium industrial solid waste with excellent CO₂ absorption performance, but the reaction activity and CO₂ absorption performance of pure carbide slag in calcium cycling will decrease with the increase of cycling times. Efficient and stable calcium-magnesium zinc composite absorbents was synthesized using carbide slag as the calcium source, MgO and ZnO as dopants. Effects of synthesis process conditions and doping amount on the absorption performance of CO₂ composite absorbent were investigated in a fixed bed reactor, as well as the changes in the internal structure of the absorbent during cyclic absorption. The results show that the absorbent synthesized by dry physical mixing method has a richer pore structure than wet mixing method. Mg and Zn elements are evenly dispersed on the surface of the carbide slag, effectively improving the anti-sintering performance and reaction activity of the carbide slag. The modified composite absorbent has higher CO₂ absorption performance during the cycling process, and after 20 cycles, CO₂ absorption capacity of the composite absorbent synthesized by dry physical mixing method can still reach 0.42 g/g.

Key words: solid waste, carbide slag, CO₂ absorption performance, dry physical mixing method, wet mixing method