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Laboratory Modeling and XRD Characterization of the Hydration Reactions of Lignite Gasification and Combustion Ash Codisposal Waste Forms

Published online by Cambridge University Press:  25 February 2011

P. Kumarathasan  and
Gregory J. McCarthy
P. Kumarathasan
Affiliation:
Department of Chemistry, North Dakota State University, Fargo, ND 58105
Gregory J. McCarthy
Affiliation:
Department of Chemistry, North Dakota State University, Fargo, ND 58105
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Abstract

Cementitious reactions in gasification and combustion ash derived from North Dakota lignite permit the fabrication of monolithic wastes forms from nonhazardous ash by-products and hazardous liquid wastes from a coal gasification plant. To better understand such cementitious reactions, x-ray diffraction has been used to characterize the hydration reaction products of crystalline phases in the gasification and combustion ashes from the Beulah, ND, complex and the crystalline reaction products formed. A cementitious lignite fly ash was also studied. pH of solutions at a liquid to solid ratio of 2.4 and times up to 14 days was measured, and compared to pH calculated from leachate chemical analyses. Reactions were monitored for up to one year. Among the principal crystalline phases in gasification ash, carnegieite (Na1.5Al1.5Si0.5O4) was the most reactive. Solution pH's for two samples of gasification ash were in excess of 13; carnegieite reaction may be responsible in part for these very high pH's. Hydration products included gaylussite, (Na2 Ca(CO3)2·5H20), a carbonate-sulfate ettringite structure phase, calcite and three or more zeolites (NaA, laumontite, faujasite and/or NaX). Ettringite and calcite were the principal hydration reaction products of scrubber ash, fly ash and the composite codisposal waste form. The formation of ettringite may be one of the principal reactions responsible for consolidation of the waste forms (along with noncrystalline calcium silicate hydrate formation which could not be observed by XRD). Ettringite was observed to decrease in abundance at long reaction times. Calcium aluminate monosulfate hydrate formed in the later stages of the fly ash reaction.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 86: Symposium N – Fly Ash and Coal Conversion By-Products III , 1986 , 159
Copyright
Copyright © Materials Research Society 1987

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References

REFERENCES

1. Hassett, D.J., McCarthy, G. J. and Henke, K.R., in Fly Ash and Coal Conversion By-Products: Characterization, Utilization and Disposal II, edited by McCarthy, G.J., Glasser, F.P. and Roy, D.M., Mat. Res. Soc. Symp. Proc. Vol.65 (Materials Research Society, Pittsburgh, 1986), pp. 285–300.Google Scholar
2. McCarthy, G.J., Hassett, D.J., Henke, K.R., Stevenson, R.J., Groenewold, G.H., Characterization, Extraction and Reuse of Coal Gasification Solid Wastes. Vol. II. Leaching Behavior of Fixed-Bed Gasification Ash Derived From Northern Great Plains Lignite, (North Dakota Mining and Mineral Resources Research Institute, Grand Forks, ND) Final Report to the Gas Research Institute, October, 1986.Google Scholar
3. Stevenson, R.J., Hassett, D.J., McCarthy, G.J., Manz, O.E., Solid Waste Codisposal Screening Study, (North Dakota Mining and Mineral Resources Research Institute, Grand Forks, ND) Draft Final Report to the Gas Research Institute, October, 1986.Google Scholar
4. McCarthy, G.J., Hassett, D.J., Manz, O.E., Groenewold, G.H., Stevenson, R.J., Henke, K.R. and Kumarathasan, P., in Fly Ash and Coal Conversion By-Products: Characterization, Utilization and Disposal II, edited by McCarthy, G.J., Glasser, F.P. and Roy, D.M., Mat. Res. Soc. Symp. Proc. Vol.65 (Materials Research Society, Pittsburgh, 1986), pp. 310–310.Google Scholar
5. Stevenson, R.J. and McCarthy, G.J., in Fly Ash and Coal Conversion By-Products: Characterization, Utilization and Disposal II, edited by McCarthy, G.J., Glasser, F.P. and Roy, D.M., Mat. Res. Soc. Symp. Proc. Vol.65 (Materials Research Society, Pittsburgh, 1986), pp. 77–90.Google Scholar
6. McCarthy, G.J. and Steinwand, S.J., in Thirteenth Biennial Lignite Symposium: Technology and Utilization of Low-Rank Coal, edited by Jones, M.L., DOE/METC-86/6036 (1985).Google Scholar
7. McCarthy, G.J., Manz, O.E., Johansen, D.M., Steinwand, S.J. and Stevenson, R.J., this volume.Google Scholar
8. Luke, K. and Glasser, F.P., in Fly Ash and Coal Conversion By-Products: Characterization, Utilization and Disposal II, edited by McCarthy, G.J., Glasser, F.P. and Roy, D.M., Mat. Res. Soc. Symp. Proc. Vol.65 (Materials Research Society, Pittsburgh, 1986), pp. 173–180.Google Scholar
9. Garvey, R.G., North Dakota Equilibrium Geochemical Model (based on the WATEGM-SE program of Palmer, C., PhD thesis, University of Waterloo, 1983), IBM-PC Implementation, North Dakota State University, 1984.Google Scholar
10. von Ballmoos, R., Collection of Simulated XRD Powder Patterns for Zeolites, (Butterworth Scientific, Ltd., Surrey, UK,1984) 106 pp.Google Scholar
11. Manz, O.E., University of North Dakota, personal communication.Google Scholar