Glass as matrix for hazardous substances

Size: px

Start display at page:

Download "Glass as matrix for hazardous substances"

Kevin Wells
6 years ago
Views:

On the possibility of using vitrified forts as anthropogenic analogues for assessment of long- term

Technology (1) Now at Vattenfall Research and Development es es Glass as matrix for hazardous

functioning over long times fundamentally difficult Necessary to rely on natural and anthropogenic

1 On the possibility of using vitrified forts as anthropogenic analogues for assessment of long- term behaviour of vitrified waste Rolf Sjöblom, Holger Ecke 1 and Evelina Brännvall Luleå University of Technology (1) Now at Vattenfall Research and Development es es Glass as matrix for hazardous substances Good capability of incorporating various elements in the structures t Evaluation of the functioning over long times fundamentally difficult Necessary to rely on natural and anthropogenic analogues They should be similar in composition and properties, and have been exposed to relevant environments during long times 1

2 Three waste forms Vitrified ash 1 from incineration of domestic waste and similar il Vitrified contaminated soil Vitrified fission products 1 from reprocessing of spent nuclear fuel (1) Together with additives Three types of analogues Natural es Glasses in archaeological specimens Glasses in vitrified hillforts Studies so far Nuclear waste together with natural es and archaeological specimens as analogues No studies found on analogues in conjunction with vitrified ash and vitrified soil es Objective and scope To evaluate the feasibility of using material in vitrified ifi forts as anthropogenic analogues for vitrified waste Comparison depends on Composition Process Environment => Scope to study composition as well as process 2

es Fly ash and other ashes Furnace Cyclone Textile filter Container for cyclone ash Container for filter ash Fractional condensation of volatile elements and compounds.

3 es Fly ash and other ashes Furnace Cyclone Textile filter Container for cyclone ash Container for filter ash Fractional condensation of volatile elements and compounds. Partial melting of the ash and consequent formation of reactive phase (A) Electric arc furnace Bottom ash + Graphite electrode (B) Plasma arc furnace MSWI residues Cu alloy + rear electrodes Incinerator bottom ash, Japan Incinerator fly ash, Japan Nuclear waste, Japan Feeder Air Hoist Flue gas Subsidiary electrode Slag & Metals Slag Metals Quenching (C) Electric resistance furnace MSWI residues ~ Flue gas Graphite electrodes Feeder (D) Metals MSWI residues Recirculated water Induction furnace Granular water slag Flue gas Slag quenching Flue gas Slag Natural, Obsidian Archaeological artefact, 9000 BC, Italy Archaeological artefact,1500 BC, Egypt Hill fort, Broborg, Sweden, average opaque Hill fort, Broborg, Sweden, clear Hill fort, Nyby, Sweden, opaque Hill fort, Shielfoot; Scotland Hill fort, Rhubh' Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% SiO2 Al2O3 CaO Fe2O3 K2O MgO MnO Na2O P2O5 TiO2 B2O3 Waste Slag Metals Metals Examples of compositions of various types of es. The compositions are figured as the oxides presented. 3

4 Vitrified contaminated soil Stabilization in situ of soil contaminated by radioactivity it The soil is made electrically conducting by introducing a current through a track of graphite, thus heating the adjacent soil to such temperatures that it starts to melt. Such partially melted soil contains ions that conduct electricity, and thus the process is made to escalate. Vitrified nuclear fission products The spent nuclear fuel is dissolved and the fission products are separated. They are then heated together with additives to form a that constitutes a durable waste form in the intended environment. Nuclear waste es differ considerably from other waste es by their loading of fission products and by their high content of phosphorus Incinerator bottom ash, Japan Incinerator fly ash, Japan Nuclear waste, Japan Natural, Obsidian Archaeological artefact, 9000 BC, Italy Archaeological artefact,1500 BC, Egypt Hill fort, Broborg, Sweden, average opaque Hill fort, Broborg, Sweden, clear Hill fort, Nyby, Sweden, opaque Hill fort, Shielfoot; Scotland Hill fort, Rhubh' Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Examples of compositions of various types of es. The compositions are figured as the oxides presented. SiO2 Al2O3 CaO Fe2O3 K2O MgO MnO Na2O P2O5 TiO2 B2O3 Waste es 4

Natural es - Obsidian Formed from lava when cooled relatively rapidly Used in the neolithic era in areas where flint was not available Studied as analogue to nuclear waste Incinerator bottom ash,

fort, Broborg, Sweden, clear Hill fort, Nyby, Sweden, opaque Hill fort, Shielfoot; Scotland Hill fort, Rhubh' Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Examples of

5 Natural es - Obsidian Formed from lava when cooled relatively rapidly Used in the neolithic era in areas where flint was not available Studied as analogue to nuclear waste Incinerator bottom ash, Japan Incinerator fly ash, Japan Nuclear waste, Japan Natural, Obsidian Archaeological artefact, 9000 BC, Italy Archaeological artefact,1500 BC, Egypt Hill fort, Broborg, Sweden, average opaque Hill fort, Broborg, Sweden, clear Hill fort, Nyby, Sweden, opaque Hill fort, Shielfoot; Scotland Hill fort, Rhubh' Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Examples of compositions of various types of es. The compositions are figured as the oxides presented. SiO2 Al2O3 CaO Fe2O3 K2O MgO MnO Na2O P2O5 TiO2 B2O3 Waste Archaeological artefacts Most of the es prepared from potash and quartz sand High content of Na and K Easy to melt, but also Susceptible to corrosion Egyptian es high in Na due to use of natural soda Incinerator bottom ash, Japan Incinerator fly ash, Japan Nuclear waste, Japan Natural, Obsidian Archaeological artefact, 9000 BC, Italy Archaeological artefact,1500 BC, Egypt Hill fort, Broborg, Sweden, average opaque Hill fort, Broborg, Sweden, clear Hill fort, Nyby, Sweden, opaque Hill fort, Shielfoot; Scotland Hill fort, Rhubh' Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Examples of compositions of various types of es. The compositions are figured as the oxides presented. SiO2 Al2O3 CaO Fe2O3 K2O MgO MnO Na2O P2O5 TiO2 B2O3 Waste 5

Incinerator bottom ash, Japan Incinerator fly ash, Japan Nuclear waste, Japan Natural, Obsidian Archaeological artefact, 9000 BC, Italy Archaeological artefact,1500 BC, Egypt Hill fort, Broborg,

Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Broborg near Stockholm, Sweden Glasses in vitrified forts show a large variety in chemical composition, between different forts

6 Incinerator bottom ash, Japan Incinerator fly ash, Japan Nuclear waste, Japan Natural, Obsidian Archaeological artefact, 9000 BC, Italy Archaeological artefact,1500 BC, Egypt Hill fort, Broborg, Sweden, average opaque Hill fort, Broborg, Sweden, clear Hill fort, Nyby, Sweden, opaque SiO2 Al2O3 CaO Fe2O3 K2O MgO MnO Na2O P2O5 TiO2 B2O3 Waste Hill fort, Shielfoot; Scotland Hill fort, Rhubh' Aird Ghamhsgail, Scotland 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Broborg near Stockholm, Sweden Glasses in vitrified forts show a large variety in chemical composition, between different forts as well as within a single fort. es Vitrified forts A fortification made of stone and earth, and usually also logs They date from 1000 BC to 1400 AD There are up to hillforts in Europe Around 200 are vitrified forts, and around half of them in Scotland (17 in Sweden) Two kinds of vitrification Melted rock Calcined rock 6

7 Cowdenknowes in N England Cowdenknowes in N England Anwoth in SW Scotland Broborg near Stockholm, Sweden 7

mechanisms compared to waste Comparison of chemical composition archaeological artefacts Archaeological

8 Broborg near Stockholm, Sweden es Comparison of chemical composition - obsidian Natural obsidian much higher in Si + Al and much lower in Na + K than waste es more durable & may show different corrosion mechanisms compared to waste Comparison of chemical composition archaeological artefacts Archaeological artefacts much higher Na + K or Na than waste es less durable & may show different corrosion mechanisms compared to waste 8

9 Comparison of chemical composition from vitrified forts Glass from vitrified forts show large ranges of variation of various elements Ranges appear to cover those of the waste es with the exception of phosphorus in nuclear waste may show similar corrosion mechanisms compared to waste Quality of heat considerations Century long dialogue regarding reason for vitrification To join the stones & make structure strong and durable (especially compared to reinforcement by logs), or As a result of enemy destruction and fire Quality of heat energy supplied at peak temperature (not total heat in a huge wood fire) Preheating Charcoal instead of wood Conclusion that charcoal infilling between the stones may be sufficient for the melting observed (see paper for details) Method used for vitrification Properties depend not only on composition but also on manufacturing process E. g. rate of cooling important => warranted to analyse ancient process used & compare with modern processes Feasibility of charcoal hypothesis above can readily be tested es 9

10 Conclusions Vitrified stone in a large number of hillforts constitute good analogues for vitrified waste Compositions vary considerably so that the ranges of parameters cover those of the waste es for most major elements Quality of heat analysis has lead to conclusions on type of method used => appears possible to reproduce ancient method & validate comparison with waste No record found on the types of studies mentioned above 10

On the possibility of using vitrified forts as anthropogenic analogues for assessment of long-term behaviour of vitrified waste

Waste Management and the Environment VI 225 On the possibility of using vitrified forts as anthropogenic analogues for assessment of long-term behaviour of vitrified waste R. Sjöblom 1, H. Ecke 2 & E.