Browsing by Author "Santos, Rafael M."
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Item Open Access Improving the yield of sonochemical precipitated aragonite synthesis by scaling up intensified conditions(Taylor and Francis, 2016-09-08) Santos, Rafael M.; Thijs, Jolien; Georgakopoulos, Evangelos; Chiang, Yi Wai; Creemers, Ann; van Gerven, TomPrecipitated aragonite can be synthesized at relatively low temperatures by combining the application of low-frequency sonication with the use of magnesium chloride additive, as demonstrated by our prior study. In the present study, new process conditions were found that promote aragonite formation while accelerating and increasing the reaction yield. It was found that Mg-to-Ca molar ratio of 3:1, together with higher slurry concentration (74 g/L Ca(OH)2) and higher power-to-volume ratio (800 W/L gross, achieved by reducing slurry volume), promoted the aragonite formation while working at a higher CO2 flow rate (2.0 NL/min), and consequently higher precipitated calcium carbonate production rate (1 g/(L · min) CaCO3). The yield was thus improved while conserving the desired product properties as follows: high polymorph purity (95.7 wt%), small and narrow particle size distribution (D[3,2] = 0.74 µm), and unique shape (hubbard squash-like).Item Open Access Influence of process parameters on carbonation rate and conversion of steelmaking slags – Introduction of the ‘carbonation weathering rate’(Wiley, 2016-07-05) Georgakopoulos, Evangelos; Santos, Rafael M.; Chiang, Yi Wai; Manovic, VasilijeAlkaline 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.