1 Material Based Strategies for Waste Treatment and Recycling Aldo R. Boccaccini Aldo R. Boccaccini Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Erlangen Germany

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3 One of the top 10 research universities in Germany 37,500 students 2,900 international students 5 faculties (Med, Nat, Phil, RW, Tech) 640 professorships About 3,000 members of academic staff About 2,100 employees in administration More than 150 degree programmes FAU – General Facts and Figures 3

4 Major Research Areas Humanities, Social Sciences, and Theology Business, Economics, and Law MedicineSciencesEngineering New Materials and Processes Optics and Optical Technology Molecular Life Science and Medicine Health Technology Electronics, Information and Communication Energy, Environment and Climate Language – Culture – Region Cohesion – Transformation – Innovation in Law and Economics

5 “Argentinean-Bavarian Initiative on Science, Technology and Innovation in Environmental Science and Technology” (ABIEST) P ABIEST A rgentinean- B avarian I nitiative on Science, Technology & Innovation in E nvironmental S cience & T echnology Plataforma de cooperación en ciencia y tecnología del medio ambiente / Environmental Science & Technology Plataforma de cooperación en ciencia y tecnología del medio ambiente / Environmental Science & Technology Objetivos Objetivos Desarrollar e implementar proyectos de investigación y desarrolloDesarrollar e implementar proyectos de investigación y desarrollo Promover el intercambio y la transferencia de conocimientos, recursos humanos, experiencia y enseñanza en Argentina y BavieraPromover el intercambio y la transferencia de conocimientos, recursos humanos, experiencia y enseñanza en Argentina y Baviera 5 Coordinadores (Baviera) Prof. R. Hilliges (Hochschule Augsburg) Prof. A. R. Boccaccini (Universität Erlangen-Nürnberg)

6 Buenos Aires, May Convenio CONICET - BAYLAT 27 Nov Financiación de proyectos conjuntos de investigación en todas las areas de la ciencia a partir de Los términos exactos de la convocatoria aun no están definidos. La convocatoria se abririá probablemente en el primer semestre de Prof. Roberto C. Salvarezza (CONICET) Prof. Andrea Pagni (BayLat) Convenio de cooperacion ABIEST (MinCyT – Ministry of Science, Technology of Baviera)

77 Outline Relevant waste streams and waste treatment: the Relevant waste streams and waste treatment: the vitrification / glass-ceramic option vitrification / glass-ceramic option Glass-ceramics from hazardous and non-hazardous Glass-ceramics from hazardous and non-hazardous waste waste -> conventional route -> powder tech./sintering Examples of recent / current research Examples of recent / current research -> Glass-ceramics from coal ash, iron slag, waste incineration residues -> Glass-ceramics from coal ash, iron slag, waste incineration residues -> Glass-ceramic foams -> Glass-ceramic foams -> Layered and graded composites -> Layered and graded composites Conclusions Conclusions

88 © Imperial College London The problem of waste: silicate residues coal ash bottom ash and flyash from waste incinerators metallurgical slag red mud (e. g. from hydrometallurgy, alumina production) air pollution control residues from waste incineration glass cullet etc. Many of these residues contain hazardous elements (e. g. heavy metals, organic compounds)

9 The role of materials science and engineering in (hazardous) waste treatment (and recycling) Optimisation of the properties of materials made from wastes in order to make them attractive for different applications (industry, construction, architecture, decoration, etc.) Increase application potential Compete favourably with conventional products In-depth assessment of the chemical durability, inertness, environmental safety, biocompatibility and toxicity Tackle the problem of social acceptance of waste-containing products !

10 The role of materials science and engineering in (hazardous) waste treatment (and recycling) High temperature processes / vitrification Room temperture proceeses / geopolymers

Vitrification One of the most promising technological options for the inertisation of waste It renders a product that can be reused or, at least, deposited in standard land-fill sites without risk By melting the residues at temperatures above 1300°C, a relatively inert glass is produced: Heavy metals can be either incorporated in the glassy product or separated from the residue by evaporation or differential precipitation High temperatures involved --> complete destruction of the organic pollutant compounds.

12 „Verfahren und Ofen zur Herstellung von Baumaterialien aus Wirtschaftsabfallstoffen“ German patent of the year 1893 (!) “Process and furnace for the fabrication of building materials from industrial residues”

13 Thermal treatment of industrial (hazardous) silicate wastes Large amounts of silicate wastes Large amounts of silicate wastes e.g. coal ash, metallurgical slag, municipal waste incineration residues, etc. e.g. coal ash, metallurgical slag, municipal waste incineration residues, etc. Vitrification Vitrification Well-established waste treatment method Well-established waste treatment method Number of papers published significantly increasing Number of papers published significantly increasing Glass-ceramic process Glass-ceramic process Vitrification + heat-treatment Vitrification + heat-treatment Applicable to many industrial wastes, including hazardous waste Applicable to many industrial wastes, including hazardous waste Environmentally acceptable alternative to land disposal Environmentally acceptable alternative to land disposal Materials have generally superior properties than parent glass Materials have generally superior properties than parent glass R.D. Rawlings, J.P. Wu, A.R. Boccaccini. “ Glass-ceramics: Their production from wastes – A Review ”, J. Mater. Sci., 41[3] (2006) R.D. Rawlings, J.P. Wu, A.R. Boccaccini. “ Glass-ceramics: Their production from wastes – A Review ”, J. Mater. Sci., 41[3] (2006)

1414 Waste volume reduction by means of vitrification Filter flyash VitrifiedproductResidues Startingwaste Processedwaste Volume

© Imperial College London15 © Imperial College London 15 As a disadvantage, vitrification is an energy-intensive process involving relatively high costs. --> Its use can only be fully justified if high- quality products with optimised properties can be fabricated, which can thus compete commercially with current materials, for example for building, architectural or insulation applications. Vitrification The most effective way to improve the properties of the vitrified products without major alterations to the process itself is the induction of a controlled crystallisation, i.e. by forming a glass-ceramic.

© Imperial College London16 © Imperial College London 16 The relationship between crystal growth and temperature NucleiCrystals Schematic illustration of the crystallization process The production of glass-ceramics Glass-ceramics are made by controlled crystallisation of a glass.

1717 Waste Compositions Coal pond ash (after drying) Iron-making melter slag Waste bottle glass (Soda-lime) SiO Al 2 O Fe 2 O (Fe total)0.3 CaO MgO K2OK2O Na 2 O MnO TiO P2O5P2O V2O3V2O Cr 2 O 3 ---

© Imperial College London18 Dense Slag-based Glass-Ceramics via Conventional Route Slag + waste glass Slag + waste glass Homogeneous & fully dense Homogeneous & fully dense Density = g/cm 3 Density = g/cm 3 Optimised after heat-treatment at 1100ºC Optimised after heat-treatment at 1100ºC glass-ceramic parent glass cm Wu et al., J. Am. Ceram. Soc. (2006)

© Imperial College London19 Properties of glass-ceramics Material Property Unit Heat-treatment As-cast 900 º C/2h 1100 º C/2h Density g/cm Thermal Expansion Coefficient [ º C] /K Vickers Hardness GPa Indentation Fracture Toughness MPa.m -1/ Young's Modulus GPa Modulus of Rupture MPa Compressive Strength MPa J. P. Wu, R. D. Rawlings, A. R. Boccaccini, J. Am. Ceram. Soc. (2006) Brittleness index (B): Ratio of fracture toughness to hardness  Low brittleness index for increased wear resistance of glass-ceramics

20 Potential Applications Specialised wear-resistant, load-bearing materials (e.g. glass-ceramic seals, electrical insulation components, substrates, grinding and abrasive materials ) Building and architectural materials (e.g. Neoparies™ glass-ceramics, Ref: Holand and Beall, Glass-Ceramic Technology, 2002)

2121 Potential applications of the glass-ceramic products Building materials such as floor and wall tiles, pipes, building blocks or bricks Grinding and abrasive medium for high-grade glass blasting materials Heat insulation material Container lining, wear resistant parts, decorative and architectural elements, high- resistant wall claddings, anti-corrosive equipment

2222 ADVANTAGES OF POWDER TECHNOLOGY Economic advantage: relative low processing temperatures (usually < 1000 °C) --> energy saving and extended life time of refractories Moreover:and… powder technology and sintering are the technologies of choice when the aim is to fabricate porous materials or glass composite materials reinforced by particles or fibres with enhanced mechanical properties, thermal shock and abrasion resistance. Products can be manufactured using ordinary Products can be manufactured using ordinary equipment available in a ceramic plant (mixing, equipment available in a ceramic plant (mixing, pressing). It does not require major investment. pressing). It does not require major investment. Suitable technology for the production of articles of Suitable technology for the production of articles of complicated shape, light-weight porous materials complicated shape, light-weight porous materials and foam-like structures and foam-like structures

Free standing thin sheet made of borosilicate glass from waste Free standing thin sheet made of waste air pollution controlled waste. Porous Glass-ceramic made of waste air pollution controlled waste. Electronic applications Bearing applications Insulation and lightweight applications Medical waste borosilicate glass Insulation/concrete/tiles Slag waste from steel plant and medical waste Materials from waste suitable for electronic chip board applications and filtering applications. Process development and engineering waste derived glass-ceramics for functional applicatons [Rama Krishna, et al. J. Noncryst. Solids (2013)]

2424 Techniques to produce porous materials Use of Hollow Glass Microspheres Use of Hollow Glass Microspheres Introduction of Gas during Processing Introduction of Gas during Processing Loose-Packed Powder Sintering Loose-Packed Powder Sintering Microwave Processing Microwave Processing Inclusion of Secondary Phase Inclusion of Secondary Phase Use of Foaming Agents Use of Foaming Agents Inclusion of Organic or Volatile Phase Inclusion of Organic or Volatile Phase Burnt-out of Polymeric Preforms Burnt-out of Polymeric Preforms

25 Porous glass-ceramics from combination of wastes 500um10um Wu et al., Adv. Appl. Ceram. (2007)

R.K.Chinnam, et al., Proc. PacRim 10 (San Diego, USA, June 2013) Borosilicate glass foams from pharmaceutical packaging residues

2727 Potential Applications Thermal insulation Thermal insulation Lightweight aggregates Lightweight aggregates Sound insulation ? Sound insulation ? High temperature filters High temperature filters Needs completely open cell structure Needs completely open cell structure

Potential applications … Construction materials such as floor and wall tiles, pipes, building blocks or bricks Grinding and abrasive medium for high-grade glass blasting materials Heat insulation structural materials Container lining, wear resistant parts, decorative and architectural elements, high- resistant wall claddings, anti-corrosive equipment

29 Waste incineration 'set to rise' Reliance on landfill to decrease due to tough targets under the European landfill directive Reliance on landfill to decrease due to tough targets under the European landfill directive "You must preferably recycle it, failing that burn it to make electricity and only bury what is left." - Bottom Ash - Fly ash - Air pollution control (APC) residues Residues of waste incineration Thermal treatment / vitrification (1990s) Valorización Energética de Residuos Sólidos Urbanos 69 waste incineration facilities with a capacity of 20 million tonnes available in Germany for the treatment of residual waste (2011).

30 Alternative APC residue treatment processes Chemical stabilisation Ferrox process (Fe 2 SO 4 + APC residues) Chemical stabilisation Ferrox process (Fe 2 SO 4 + APC residues) The VKI process (H 3 PO 4 + CO 2 ) WES-PHix process (H 3 PO 4 ) Solidification Cement based process, solidification with water and Bitumen encapsulation Solidification Cement based process, solidification with water and Bitumen encapsulation Thermal treatmentVitrification: Conventional vitrification Thermal treatmentVitrification: Conventional vitrification Plasma vitrification Plasma vitrificationMeltingSintering

© Imperial College London31 Plasma technology -High energy density and temperatures, fast reaction times  potential for large throughput in a small facility footprint - Sharp thermal gradients  high quench rates  minimise the reformation of persistent organic pollutants - Rapid start-up and shut down times - Gas stream produced much smaller than with conventional combustion process, easier to manage Gomez, E., Boccaccini, A. R., et al., J. Haz. Mat., 2009, 161, 614 – 626.

32 Beneficial applications of APC residues derived glass Tiles Cast glass Glass-ceramics Amutha Rani D, et al., Int. J. Appl. Ceram. Tech. (2009)

3333 Comprise both vitreous and crystalline components. Comprise both vitreous and crystalline components. The major component may be a crystalline phase with residual vitreous phase, or the vitreous phase may be the major component, with particles of a crystalline phase dispersed in the glass matrix. The major component may be a crystalline phase with residual vitreous phase, or the vitreous phase may be the major component, with particles of a crystalline phase dispersed in the glass matrix. Both the matrix, which can be itself a glass-ceramic, and the inclusions can come from waste. Both the matrix, which can be itself a glass-ceramic, and the inclusions can come from waste. Glass Composite Materials (GCM’s) (Suggested for nuclear waste encapsulation, W. E. Lee et al.)

3434 Glass and glass-ceramic matrix composites from combinations of silicate residues Matrix: residue without toxic elements Inclusions: toxic particulate waste Concept: encapsulation of residues in an inert matrix Boccaccini, A. R., et al., Env. Technol. (1996)

35© Imperial College London35 Glass and glass-ceramic matrix composites from silicate wastes Boccaccini, A. R., et al., "The Multibarriers-System as a Materials Science Approach for Industrial Waste Disposal and Recycling: Application of Gradient and Multilayered Structures", Environmental Technol. 17 (1996) ) Increase the leaching resistance and chemical durability of hazardous waste containing products by maintaining the highest possible waste content in the component Improve the effective engineering and technological properties of the products in relation to potential industrial applications Multilayered and graded glass matrix composite concept:

3636Conclusions Vitrification / Glass-ceramic process is an attractive method to treat (hazardous) wastes Vitrification / Glass-ceramic process is an attractive method to treat (hazardous) wastes Several wastes investigated (coal flyash, metallurgical slag, APC residues) Several wastes investigated (coal flyash, metallurgical slag, APC residues) Fully dense, high-strength glass-ceramics Fully dense, high-strength glass-ceramics Tailored properties by heat treatments Tailored properties by heat treatments Dense and highly porous glass-ceramics Dense and highly porous glass-ceramics Novel materials, e.g. foams, glass-ceramic composites, layered materials, of great interest to enhance the technical application of the products Novel materials, e.g. foams, glass-ceramic composites, layered materials, of great interest to enhance the technical application of the products Social acceptance, commercial interest?

37 37 Understanding glass- ceramics from waste Formulating compositions and finding applications Application oriented research of waste derived glass-ceramics PastPresentFuture  Formulations with waste and hazardous waste Traditional and „new“ waste Tackling waste variability  Finding applications to replace raw materials consumption  Low energy consumption and faster processing for industry approval. ?

3838 Bridging the gaps for the future of waste derived glass-ceramics Research Mindset Innovative Applications Low cost processing Social acceptance Present Future ? ??

© Imperial College London39 © Imperial College London Relative toxicity using cell culture tests. Data normalised with respect to the toxicity of petri dish glass. ( ) Glass-ceramic, (  ) vitrified flyash prior to crystallisation Boccaccini et al., Ceram. Bull. (1997)

40 Acknowledgements Muchas Gracias! Mr C. Rama Krishna and former colleagues at Imperial College London (Prof. C. Cheeseman, Dr. A. Devaraj) GlaCERCo – ITN “Glass and Ceramic Composites for High Technology Applications “ Initial Training Network