Insights into the reinforcing mechanism for CO2 atmosphere in the application process of steel slag ultra-fine powder

Abstract

Abstract In this paper, we discussed the influence of steel slag ultra-fine powder for CO2 sequestration including the influence of the experiment parameters on the CO2 sequestration ratio and the reinforcing mechanism for CO2 atmosphere in the application process of steel slag ultra-fine powder. In the process of steel slag ultra-fine powder for CO2 sequestration, the CO2 sequestration ratio and reaction rate were influenced by particle size, solid-to-liquid ratio, temperature, agitation rate and CO2 flow rate. The reaction rate was increased with the solid-to-liquid ratio, temperature and agitation rate increasing, but CO2 sequestration ratio was less obviously influence. It showed that the technology of steel slag ultra-fine powder effectively increased the CO2 sequestration ratio. The most effective composition of CO2 sequestration using steel slag ultra-fine powder was oxide and/or hydroxide of Ca and Mg. About contribution of CO2 sequestration ratio, the rate of carbonating reaction of Mg element was 20.86%, and that of Ca element was 59.80%. It was because there was still much Mg and Ca elements without entering into the carbonating reaction, the reason of which was non-activated Mg and Ca failing to involve in the carbonating reaction. Moreover, part amount of activated Mg and Ca involving in the carbonating reaction generated CaCO3 and MgCO3 covering on the steel slag powder, led to remaining amount of activated Mg and Ca cannot involving in the carbonating reaction. Moreover, the ultrafine steel slag-doping could effectively increase the density and compressive strength of block under CO2 curing.