Influence of process parameters on carbonation rate and conversion of steelmaking slags – Introduction of the ‘carbonation weathering rate’

Alkaline industrial wastes are considered potential resources for the mitigation of CO2 emissions by simultaneously capturing and sequestering CO2 through mineralization. Mineralization safely and permanently stores CO2 through its reaction with alkaline earth metals. These elements are found in a variety of abundantly available industrial wastes that have high reactivity with CO2, and that are generated close to the emission point-sources. Among all suitable industrial wastes, steelmaking slag has been deemed the most promising given its high CO2 uptake potential. In this paper, we review recent publications related to the influence of process parameters on the carbonation rate and conversion extent of steelmaking slags, comparing and analyzing them in order to define the present state of the art. Furthermore, the maximum conversions resulting from different studies are directly compared using a new index, the Carbonation Weathering Rate (CWR), which normalizes the results based on particle size and reaction duration. To date, the carbonation of Basic Oxygen Furnace steelmaking slag, under mild conditions, presents both the highest carbonation conversion and CWR, with values equal to 93.5% and 0.62 μm/min, respectively.