Carbonation of Industrial Residues for CCUS: Fundamentals, Energy Requirements and Scale-up Opportunities

Conference Dates

May 22-26, 2017


Injection in deep geological formations is considered as the most promising option for CO2 storage. Limitation of the available storage capacity with acceptable leaking rates may limit its application, at least in some geographical locations, thus prompting the need for developing alternative storage options. Among these, accelerated carbonation has been proposed as an effective way for carbon dioxide sequestration. This process mimics natural weathering, where CO2 reacts exothermically with alkaline elements present in natural metal-oxide bearing material, forming thermodynamically stable and benign carbonates. A valuable source of alkalinity for the carbonation process is represented by alkaline industrial residues produced by different industrial activities such as steelmaking, cement production, waste incineration and coal combustion. These residues are typically more reactive than minerals and are often available at CO2 point source emissions. This presentation will give an overview on the research activities carried out by our group in this field, which was mostly performed on the so called “wet” or “thin-film” route, operated adopting a liquid to solid ratio below 1 l/kg. The results obtained through lab-scale tests performed on different types of industrial residues will be first presented, making reference specifically to EAF, AOD and BOF steel slags. Based on these results, the energy requirements of the wet route carbonation will be presented, discussed and compared with those of the more traditional slurry-phase route, allowing to identify the critical steps of the overall process route. Finally, scale-up opportunities of the wet-route carbonation, based on a combined carbonation-granulation process, will be discussed. The aim of this combined process is to obtain artificial aggregates suitable for use in civil engineering applications, thus potentially reducing the consumption of abiotic natural resources and reducing the need for disposal of the residues. The results obtained in a lab-scale granulator and more recently in a pilot-scale rotary reactor, in terms of CO2 uptake, environmental and mechanical properties of the obtained granules, will be presented.

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