Fly ash: Looking beyond the conventional use

1. Fly ash: Looking beyond the conventional use S. K. Nath, T. C. Alex, R. Kumar & Sanjay Kumar CSIR-National Metallurgical Laboratory, Jamshedpur

2. What is Fly ash A by-product or the finely divided residue resulting from the combustion of pulverized coal in thermal power plants.

3. Potential of Fly Ash • A alumino-silicate material • Fine PSD with good flow ability • Combination of crystalline and glassy phases • Pozzolanic characteristic • Good durability • Refractory properties

4. Waste to Resource With right process you can turn it into a useful product Waste is a resource, but in the wrong place The Changing Mindset

5. Fly Ash Success stories

6. State of the Art Bandra Worli Sea Link used HVFA concrete Milwaukee Art Centre, USA BAPS Temple, Chicago UTAH State Capitol Building

7. Fly ash Utilization in India Better than Global Utilization trend Global Utilization : 39% Ample scope for new applications and technology

8. Conventional Fly ash Utilization (%) Around 72% Fly ash is used in Cement & Building Materials

9. Fly Ash Research: Global Trend

10. Fly Ash Utilization in non-conventional way • Geopolymer • Ceno-sphere separation • Extraction of heavy metals • Ceramic products • High performing Composites • Wood & ply-wood substitutes • Light weight insulating material • Pre-processing

11. Fly ash R&D at CSIR-NML • First research project on fly ash was carried out in 1968 • Main activities started in 1994, focus on high value added ceramic products • National Seminar on Fly ash in 1999 • Preprocessing of fly ash started in 2000, completed project on cement • Major activities on geopolymer started in 2004, pilot plant setup in 2011 • MoU with C-FARM in 2009 • Fly ash is one of the major activities under 12th Five year plan during 2012-2017

12. Domain of Fly ash R&D at CSIR-NML

13. Green Process & Technology using Geopolymerization of Fly ash

14. Geopolymerization Geopolymer......... Synthetic alkali alumino-silicate material Geopolymer can be described by the general formula Mn [ – (SiO2)z – AlO2 ]n . wH2O M : Alkaline element, z : 1, 2 or 3, and n : Degree of polymerization

15. Why Geopolymer … Simple process Wide range of applications 80% less CO2 generation than OPC Low energy & water consumption Better durability & longevity Qualifies as GREEN

16. Excited Examples: Geopolymer Concrete Geopolymer concrete sleepers of operating railway, St-Petersburg – Moscow were placed in 1988 and operational.

17. Geopolymer Concrete Geopolymer in Airport runway >20 MPa strength in 4 hours

18. Geopolymerisation of fly ash

19. Why Fly Ash is Suitable ?? <100 µm particle size Flow behaviour Si-Al ratio 1.6 – 2.2 >30% glassy phase Synthetic material

20. Suitability in Indian Context • Abundantly available • Either free of cost or low cost material • Cement making is of great concern due to depleting natural resources and increasing CO2 generation • 100% utilization of fly ash notification by MoEF, Nov. 2009 • Exploit the full potential of fly ash as source of silica and alumina: >90% fly ash can be used in many products • Indian fly ash is suitable for geopolymerization • The average ambient temperature in India is 27°C and average humidity is >50%,

21. CSIR-NML Research on Fly Ash Geopolymer

22. Self glazed tiles • Low temperature processing • No additional process for glazing Patent : 2626/DEL/2005, 30/09/2005 and 728/DEL/2006, 30/11/2005

23. Paving blocks Synergistic Utilization of fly ash, BF slag, COREX slag, steel slag, zinc slag and kiln dust • Ambient temperature processing • Ready to use in 7 days • Product confirms IS-15658:2006 specification

24. Lab Scale to Pilot Scale

25. Geopolymer pilot plant – 1st in India Supported by FAU- Department of Science & Technology • Fully automatic, with ~4 ton/shift capacity • Can produce different shapes paving blocks • Uses vibration, or hydraulic pressing or combination of both A step forward in translating process into technology

26. Pre-processing of fly ash

27. Methods

28. Air Classification using ATP50 High speed air classifier with max rotation speed 20000, can classify very fine fractions also

29. Use of different size fraction in PPC

30. Strength Development !! Coarse fraction shows lot of un-reacted fly ash particles even after 28 day hydration More reaction product in the fine fraction is the reason for strength development

31. Mechanically Activated Fly Ash

32. What is Mechanical Activation • Changes that takes place during mechanical activation • Increase in surface area • Stresses in solid structure • Defects induced in the solid structures • Phase transformations • Repeated welding of interfaces • Fracture leading to dynamic creation of fresh surfaces for reactions • Chemical reactions

33. Strength Development in cement

34. X50 ~ 5 μm 60 oC X50 ~ 5 μm X50 ~ 3 μm X50 ~ 36 μm MA Fly ash in Geopolymer

35. Geopolymer Cement Very high (120 MPa) strength

36. Ceramics using Fly Ash

37. Wear Resistant Ceramics • Excellent compressive strength • Very hard and dense • Excellent wear resistant properties • Can be used for wear resistant applications in pipelines, chutes, bunkers, hoppers, mills etc Fly ash (30-40 wt% ) based wear resistance ceramics substitute for high alumina based ceramic tiles

38. Refractory Bricks • 50% fly ash can be used • Equivalent of IS-6 fire-clay bricks • Sintered at lower temperature

39. Ceramic Tiles • Produced at 980-1050 C • Improved scratch hardness • Better compressive strength • Satisfy EN specification • Possibility to use other waste in addition to fly ash Patent No. DEL/1800/96, 005NF and 13005NF 1998/03

40. Thank You We are caring for environment

43. Fly ash Utilization: A Giant Leap Year 2009 Generation : 6.5 billion tonnes Utilization : 39% Source: ACAA

44. Geopolymer as Products • Blended cements for structural applications • Enhanced acid and fire resistant cements • Toxic waste encapsulation • Advanced composites (high temperature ceramic) • Adhesives

45. Commercial Realty Zeobond, Australia is making geopolymer concrete, using fly ash as one of the component

46. Geopolymer Pilot Plant: 1st in India • Provide valuable design and operational data for the setting up of a large size plant, • Assess the impact of variability of raw materials (fly ash, water etc) quality, • Fine tune operational parameters, • Work out a more precise techno-economics for the process, • Act as demonstration unit and instill confidence in potential user of the technology since the technology would be used in India for the first time, • Development of other geopolymer products since the plant has a modular character

47. Immense Application Potential

48. Fly Ash, Geopolymer & Sustainability Towards Sustainability Geopolymer Simple processing Low energy consumption Low CO2 generation Low water requirement Low cost Easily available Good properties Fly ash

49. Reactivity of MA Fly ash

50. zWz = E = e as E = Eu -  (e as) = sWz sWz = E =  (e as) Degree of dispersion Rittinger Stage Aggregation Agglomeration Grinding time, h What is Mechanical Activation Grinding and Mechanical Activation • Changes that takes place • Increase in surface area • Stresses in solid structure • Defects induced in the solid structures • Phase transformations • Localised and overall thermal effects • Repeated welding of interfaces, and • Fracture leading to dynamic creation of fresh surfaces for reactions etc. • Chemical reactions • z = efficiency of grinding • Wz = work expended during grinding • E = change in bonding energy due to grinding • e = specific surface energy • as = specific surface area