Synergistic mechanisms of steelmaking slag coupled with carbide slag for CO2 mineralization

Mineralization is an important means for emission reduction and utilization of CO2. Industrial calcium-based byproducts such as steelmaking slag and carbide slag are often used as inexpensive mineralizers for CO2. In this investigation, the pH was tested on-line during the mineralization process of CO2 and steelmaking slag, carbide slag and the compounded system of steelmaking slag and carbide slag. The characteristics of the raw materials and mineralization products were determined using XRD, XRF, LSA, FT-IR, SEM-EDX and TGA. The results indicated that there was a synergistic effect of steelmaking slag coupled with carbide slag for mineralization of CO2, the mineralization rate was accelerated and mineralization efficiency increased. When the mass ratio of steelmaking slag and carbide slag was 1:1, the mineralization rate and efficiency were increased by 19.0 % and 23.1 %, respectively. The mineralization products of the compounded system covered on the surface of the steelmaking slag firstly, which can effectively avoid the covering on the surface of carbide slag particles, and it was beneficial to increase the mineralization rate and mineralization efficiency of carbide slag. The alkali excitation of steelmaking slag may be another reason to improve the mineralization efficiency. Furthermore, XRD, TGA and FT-IR revealed that there was unreacted Ca(OH)(2) in the mineralization products of carbide slag, but none in the products of the compounded system of steelmaking slag and carbide slag. The possibility of the scale-up mute for CO2 mineralization using SS/CS was discussed.

Automated summary

The study found that the combination of steelmaking slag and carbide slag can increase the mineralization rate and efficiency of CO2, beneficial for improving the mineralization rate and efficiency of carbide slag, which may be related to alkali excitation.