Accelerated Carbonation of Contaminated Land and Waste Residues as a Contribution to Carbon Sequestration M. Fernández Bertos 1 , S.J.R. Simons 1 , C.D. Hills 2 , P.J. Carey 2 1 Centre for CO2 Technology, Department of Chemical Engineering, University College London 2 Centre for Contaminated Land Remediation, School of Earth and Environmental Science, University of Greenwich NOVEL TECHNOLOGY: ACCELERATED CARBONATION It is a controlled accelerated version of the naturally occurring carbonation process. Acts positively in the encapsulation of heavy metals in certain wastes, improving chemical and physical properties of the treated materials. US5, 997, 629 WO 01/34294 A1 OPTIMISATION OF REACTION CONDITIONS Reactivity of CO 2 Diffusivity of CO 2 EXAMPLE: Air Pollution Control (APC) Residues effective carbonation ? 6 8 10 12 14 EA FA1 EA FA2 EA FA3 SE FA CL FA KI FA pH untreated carbonated 6 8 10 12 14 EA FA1 EA FA2 EA FA3 SE FA CL FA KI FA pH untreated carbonated DETERMINATION OF ACCELERATED CARBONATION KINETICS Diffusion controlled reaction DECISIO N PROCESS YES REACTION MODEL YES Carbonation chambers-carbonation under constant positive pressure 0 0.2 0.4 0.6 0 10 20 t/t0.5 g (al p ha ) 10°C 23°C 43°C 62°C Isothermal experiments main unknown? is it feasible? Carbon8 Technologies Cleaning-up with carbon MSWI Ash waste Contaminated Land Slags Volume produced? Current disposal route? Waste characteristics? CO 2 Batch reactor-carbonation under controlled T & P Ca(OH) 2 + CO 2 CaCO 3 + H 2 O Intensity 0 100 °2θ 20 30 40 50 60 500 400 600 300 200 Ca(OH) 2 Carbonated A PC KCl vaterite calcite NaCl C3S vaterite Ca(OH) 2 calcite CaSO4 KCl KCl vaterite NaCl CaF2 SiO2 CaSO4 APC as received Carbonated A PC 0.1 1 10 100 1000 10000 SE FA CL FA KI FA EA FA1 EA FA2 EA FA3 Lead (mg/kg) uncarbonated carbonated 0.1 1 10 100 1000 10000 SE FA CL FA KI FA EA FA1 EA FA2 EA FA3 Lead (mg/kg) uncarbonated carbonated Content of lead in the APC residues before and after carbonation pH change of APC residues before and after carbonation BSI of resin mounted APC residues before carbonation BSI of resin mounted APC residues after carbonation slag b PFA * cyclone dust furnace dust slag c slag a GGB S * filter cake MSW bottom ash * CS MSW fly ash * de-inking ash * SSS * OP C * 0 5 10 15 20 0 10 20 3 0 40 50 60 wt. % CaO weight gain carbonation (%) Percentage of weight gain upon carbonation vs weight percentage of free lime in waste Advantages of ACT  Rapid treatment (minutes) as opposed to days or months with other technologies  Waste CO 2 is converted into carbonate salts, providing carbon credits  The immobilisation of heavy metals in carbonated products renders them permanently non-hazardous or inert Process results in increased product density, lower product volume, particle size is controllable  The product is non hazardous and can be used as a secondary aggregate Applications ACT treats contaminated soil and waste to provide a rapid cost-effective solution for:  Brownfield land remediation and development  Industrial waste recycling and re-use: Steel Slag MSWI ashes, Hazardous sludges, Hazardous gas streams Services and Capabilities Carbon8 can provide customised solutions for waste treatment and land remediation starting with analysis of waste streams through to development of fully engineered and operated waste treatment solutions. weight gain upon carbonation(%) %carbonated selected 0 1 2 3 4 5 6 7 8 0 100 200 300 400 500 600 particle size ( µm) % particles 0 10 20 30 40 50 60 70 0 1 2 3 4 5 6 7 8 0 100 200 300 400 500 600 0 10 20 30 40 50 60 70 % particles weight gain upon carbonation(%) %carbonated selected 0 1 2 3 4 5 6 7 8 0 100 200 300 400 500 600 particle size ( µm) % particles 0 10 20 30 40 50 60 70 0 1 2 3 4 5 6 7 8 0 100 200 300 400 500 600 0 10 20 30 40 50 60 70 % particles 0 2 4 6 8 10 12 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 w 0 2 4 6 8 10 12 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 selected w/s 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 w weight gain upon carbonation (%) 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 2 4 6 8 10 12 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 w 0 2 4 6 8 10 12 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 selected w/s 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 w weight gain upon carbonation (%) 0 2 4 6 8 10 12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 water-to-solid ratio %CO 2 consumed 0 1 2 3 4 5 6 7 0 300 600 900 1200 selected time %CO 2 consumed 0 1 2 3 4 5 6 7 0 300 600 900 1200 selected time selected time time (min) ( ) α 1 ln 1 T R 186 . 8 exp 94 13 . 0 dt α d − − ⋅       − = 0 CO CO 0 CO CO 2 2 2 2 P P P P α − − = τ () α f RT E - exp A dt dα A       = () () () ∫ ∫ = = t 0 0 dt T k α f d dα α g α Experiments at constant w/s 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 0.5 1 1.5 2 2.5 3 w/s = 0.2 w/s = 0.3 w/s = 0.4 w/s = 0.5 holt-cutler Fractional conversion, α Reduced time, t/t 0.5 0 0.2 0.4 0.6 0.8 0 1 2 3 4 5 80% CO2 60% CO2 50% CO2 25% CO2 holt-cutler Fractional conversion, α Reduced time, t/t 0.5 Experiments at constant [CO 2 ] OBJECTIVE: The application of Accelerated Carbonation to sequester CO 2 in contaminated soils and haza rdous wastes at large scale as a cost-effective and sustainable route for waste management CO 2 consumption Encapsulation of contaminants XRD Diffractogram of APC residues before and after carbonation Fernández Bertos, M., Simons, S., Hills C.D. and Carey, P. J., A Review of Accelerated Carbonation Technology in the Treatment of Cement-based Materials and Sequestration of CO 2 . Journal of Hazardous Materials 112(3), 193-205 (2004) Fernández Bertos, M., Li, X., Simons, S. R. J., Hills C.D. and Carey, P. J., Investigation of accelerated carbonation for the stabilisation of MSW incinerator ashes and the sequestration of CO 2 . Green Chemistry 6, 428-436 (2004)