7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

1. The use of alkaline industrial waste in the capture of carbon dioxide J. Jaschik, M. Jaschik, K. Warmuzinski Institute of Chemical Engineering Polish Academy of Sciences Gliwice, Poland 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

2. Mineral carbonation • One of a number of options for the capture of CO2 • The fixation of CO2 in the form of inorganic, insoluble carbonates, based on the exothermic (spontaneous) reaction of CO2 with metal oxide-bearing materials: • MO + CO2 → MCO3 + heat • Source of metal oxides: • naturally occurring silicate rocks (serpentine, olivine, wollastonite, talc) • alkaline industrial residues (fly ash, stainless steel slag, oil shale ash, cement, concrete, MSWI-municipal solid waste incinerator - residue) 2 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

3. Advantages: 1. permanent and safe binding of CO2 2. geologically stable and environmentally neutralcarbonates may bestored for long periods of time 3. products of mineral carbonation may be reused Mineral carbonation (IPCC Special Report on Carbon Dioxide Capture and Storage) Disadvantages: 1. slow kinetics of carbonation processes 2. large amounts of minerals required 3. cost 3 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

4. Costs of storage per tonne of CO2 avoided • IPCC Special Report on Carbon Dioxide Capture and Storage, Cambridge University Press, Cambridge, 2005 • W.J.J. Huijgen, R.N.J. Comans: Mineral CO2sequestration by carbonation of industrial residues. Literature overview and selection of residue, Report ECN-C-05-74, December 2005 • Stolaroff J.K., Lowry G.V., Keith D.W.: Using CaO- and MgO-rich industrial waste streams for carbonsequestration, Energy Conversion and Management, 46 (2005), 687-699 4 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

5. Utilization of fly ash • (+) Lower cost of carbonation due to: • pulverized form of fly ash, which does not require additional mechanical processing • availability close to CO2 source; fly ash does not have to be mined and transported • no need for thermal processing • (+) Faster kinetics of carbonation; main reactive species are CaO and Ca(OH)2 • (+) Environmental and commercial advantages: • stabilization of alkaline waste material (leaching of potientiallyharmful elements from the residue decreases due to carbonation) • by-product with high commercial value 5 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

6. 4. (-) Limited storage capacity Production of ashes and slags from power stations in Poland (Mt/year) 6 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

7. Generation of combustion by-products in Europe in 2008 Bottom ash 8.6% Slag 2.4% Fluidized ash 1.8% Ash with desulphurization products 0.6% Gypsum 20% Fly ash 66.6% Total: about 100 Mt 7 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

8. Process routes for aqueous carbonation 1. Direct carbonation Off-gas Liquid phase Minerals/Waste Water Solid product Flue gas 2. Indirect carbonation Off-gas Liquid phase Minerals/Waste Water Solid product PCC Solid product Flue gas 8 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

9. Reaction mechanism • Extraction/Dissolution • CaO (s) + H2O ↔ Ca(OH)2(s) • Ca(OH)2(s) ↔ Ca+2 + 2OH-(solid surface) ↔ Ca+2 + 2OH-(bulk solution) • Ca/Mg-silicate (s) + 2H+ ↔ Ca/Mg+2 + SiO2(s) + H2O • Availability of lime to hydration and carbonation reactions is of key importance • solution composition • specific surface area • Extraction of Ca/Mg ions from mineral matrix is strongly affected by acids 9 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

10. Reaction and Precipitation CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- ↔ 2H+ + CO3-2 Ca+2 + HCO3- ↔ H+ + CaCO3(s) Mg+2 + HCO3- ↔ H+ + MgCO3(s) Ca+2 + CO3-2 ↔ CaCO3(s) Mg+2 + CO3-2 ↔ MgCO3(s) Ca+2 + SO4-2 ↔ CaSO4(s) Sulphate ions, alongside the carbonation ions, produce insoluble layers of CaSO4 and CaCO3 which coat the surface of ash particles, thus preventing further dissolution of calcium oxide The coating of precipitated solids building on ash particles makes the recycling of unconverted feedstock impossible 10 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

11. Characteristics of ash studied Fly ash from lignite fluidized bed combustion (Turowpower station) t = 760°C η = 91% Production and emission in 2013: Energy –45,965,390 GJ Heat –650,821 GJ Fly ash – 1,043 Mg SO2 – 21,416 Mg NO2 – 9,180 Mg CO – 727 Mg CO2 – 9,994,790 Mg 11 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

12. Chemical composition 12 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

13. Phase composition 13 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

14. Morphology • FBC ash (fly ash from lignite fluidized bed combustion) • Irregular shape • Porous and uneven surface • PF ash (fly ash from pulverized coal fired boilers) • Regular spherical shape • Smooth surface 14 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

15. Particle size distribution Dv(0.1) = 5.61 μm Dv(0.5) = 32.86 μm Dv(0.9) = 130.71 μm D[3,2] = 11.81 μm D[3,4] = 62.31 μm Surface and porosity BET = 6.664 m2/g Micropore area = 0.588 m2/g Total pore volume = 3.71 mm3/g Micropore volume = 0.026 mm3/g Average pore size = 14.24 nm 15 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014 Particle size distribution: Dv(0.1) = 5.611 μm Dv(0.5) = 32.856 μm Dv(0.9) = 130.714 μm BET = 6.664 m2/g Particle size distribution: Dv(0.1) = 5.611 μm Dv(0.5) = 32.856 μm Dv(0.9) = 130.714 μm BET = 6.664 m2/g

16. Experimental Parameters of dissolution Temperature 20-80 ºC Ash/water ratio 1/4 – 1/100 Stirrer speed 300-1100 min-1 Time of dissolution about 5 hours Experimental setup1 – reactor, 2 – heating jacket, 3 – inlet of solution and solid phase, 4 – cooler, 5 – peristaltic pump, 6 – sample withdrawal, 7 – mixer, T – temperature control, N – mixer speed control 16 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

17. Principal objectives of the study Determination of the potential of fly ash from lignite fluidized bed combustionto capture carbon dioxide via mineral carbonation Determination of the optimum parameters for the process of dissolution of solid alkaline waste, which is a crucial step in the enhanced CO2 carbonation 17 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

18. Effect of stirrer speed t = 20°C, ash/water ratio = 1:50, 1:20 ↕ 18 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

19. Effect of temperature Stirrer speed = 600 min-1, ash/water ratio = 1:20 ↓ 19 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

20. Effect of ash to water ratio Stirrer speed = 600 min-1, t = 20°C ↑ 20 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

21. Proposed scheme of indirect carbonation Step 1 Reactive species are extracted from the ash Step 2 Reaction with CO2 and precipitation of carbonates take place 21 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

22. Conclusions • The results obtained clearly show that the fly ash studied can be employed in the mineral carbonationof CO2. The high content of calcium oxide and the considerable proportion of the reactive form of CaO compared with the total calcium content lead, over a short period of time, to a solution saturated with calcium ions • The solution, despite the presence of considerable amounts of calcium sulphate in the fly ash, still remains alkaline (pH of about 12.5).Therefore, the next step of carbonation in the presence of carbon dioxide should occur with relatively high yield • The content of sulphate and carbonate ions in the liquid phase has to be closely monitored, as they lead to the formation of insoluble layers on the surface of particles and thereby strongly inhibit the dissolution • The indirect route is proposed for the future study of aqueous carbonation process using ash from lignite fluidized bed combustion 22 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014

23. THANK YOU FOR YOUR ATTENTION 7th International Scientific Conference on Energy and Climate Change Athens, 8-10 October 2014