Wet versus slurry carbonation of EAF steel slag

The CO2 uptake and Ca-to-carbonate conversion yield attained by wet and slurry-phase carbonation of stainless steel slag are reported. A maximum CO2 uptake of 180 g CO2/kg slag was achieved under wet conditions (50 degrees C, 3 bar CO2, 0.4 l/kg), corresponding to a Ca-to-carbonate conversion yield of 50%. The slurry-phase process, even when adopting more energy-intensive operating conditions, did not improve the CO2 uptake kinetics and conversion yield in comparison to the wet treatment. The mineralogy of the carbonated slag exhibited a decreased content of silicate phases (Ca2SiO4 in particular), a marked reduction of Ca and Mg oxides, and a noteworthy increase of calcite. (C) 2011 Society of Chemical Industry and John Wiley & Sons, Ltd