Accelerated carbonation by cement kiln dust in aqueous slurries: chemical and mineralogical investigation

Abstract

Cement kiln dust accelerated carbonation in aqueous slurries at 25°C and 3 bar PCO2 was investigated by X-ray diffraction analysis, solution chemistry, scanning electron microscopy, and energy dispersive spectroscopy to better understand chemical and mineralogical processes governing CO2 uptake. Dissolution of lime, portlandite, and ettringite occurs primarily in the carbonation process. These provide Ca2+ ions to react with CO32− ions leading to calcite bulk precipitation from solution. Concomitantly, the dissolution of Ca-(Al)-silicate grains takes place but it is limited by the formation of a Si-rich and Ca-depleted rim which appears onto the grain surfaces due to an initial hydration step. The Si-rich decalcified rim hinders the diffusion of Ca2+ ions from the core of silicate grains to the bulk solution. The diffusion of Ca ions through the rim is then the rate limiting step for the carbonation of Ca-(Al)-silicate, that accounts for up to 4% of the carbonation potential. Achieved results elucidate the processes governing CO2 uptake by cement kiln dust, and are fundamental in the perspective of enhanced CO2 sequestration by cement kiln dust

Accelerated Direct Carbonation of Steel Slag and Cement Kiln Dust: An Industrial Symbiosis Strategy Applied in the Bergamo–Brescia Area

“…After carbonation, the sample was more homogeneous, with visible calcite crystals growing on Ca2SiO4 particles (see the Supplementary Materials, Figure S3). The CKD showed calcite as the main phase, with interesting small crystals of CaCO3 growing differently from the initial crystal of calcite due to the absence of control of particle growth of the interested product (Figure 6c,d) [63].…”

Geochemical Negative Emissions Technologies: Part I. Review

“…On a global scale, it is estimated that 7 Gt of these alkaline mineral by-products/wastes are produced annually, with a combined potential to capture and store CO 2 away from the atmosphere at 2.9-8.5 Gt yr. −1 by 2100 (Renforth, 2019). More specifically, these materials include: (i) iron and steelmaking slags (blast furnace, basic oxide, electric arc furnace, ladle furnace, and argon oxygen decarburization slags) (Mayes et al, 2018;Pullin et al, 2019;Reddy et al, 2019;Luo and He, 2021); (ii) cement wastes (cement and concrete wastes, construction and demolition wastes, cement kiln/bypass dust, recycled calcium sulfates, and blended hydraulic slag cement) (Huntzinger et al, 2009a;Medas et al, 2017;Pedraza et al, 2021); (iii) ashes and relevant residues [bottom ash from furnaces and incinerators (municipal solid waste incinerator bottom ash, fly ash, boiler ash, coal slag, oil shale ash), air pollution control residues (cyclone dust, cloth bag dust), and fuel combustion ashes (coal fly ash, lignite fly ash, oil shale, biomass ashes)] (Alba et al, 2001;Baciocchi et al, 2006;Sun et al, 2008;Zhang et al, 2008;Montes-Hernandez et al, 2009;Prigiobbe et al, 2009;Lombardi et al, 2016;Brück et al, 2018;Liu et al, 2018;Ji et al, 2019;Vassilev et al, 2021); (iv) mine and mineral processing wastes (asbestos tailings, nickel tailings, diamond tailings, and red mud) (Wilson et al, 2010(Wilson et al, , 2014Power et al, 2014Power et al, , 2020Gras et al, 2017;Mervine et al, 2018); (v) alkaline paper mill wastes (lime kiln residues, green liquor dreg, paper sludge) (Pérez-López et al, 2008;Sun et al, 2013;Li and Sun, 2014;Spínola et al, 2021); and (vi) reject brines from desalination (...…”