Sulfur Polymer Cement, A Solidification and Stabiliution Agent for Radioactive and Hazardous Wastes
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Abstract
There are no known perfect solidification and stabilization agents for radioactive or hazardous wastes, so the search continues for individual agents for specific wastes. The US Department of
Energy began testing sulfur polymer cement (SPC) as a radioactive and hazardous waste solidification and stabilization agent because of its unusual properties. SPC is a sulfur polymer composite material that begins melting between 110 and 120 degrees C (230 and 248 degrees F), with an optimum pour temperature between 130 and 140 degrees C (266 and 284 degrees F). The compressive strength of SPC upon cooling averages 27.6 MPa (4,000 psi). Its mechanical strengths continue to increase for at least two years to approximately triple the original strength. As a proven construction concrete, SPC has demonstrated the ability to survive for years in acids and salts that destroy or severely damage hydraulic concretes in months or even weeks. Perhaps SPC's strongest selling point is that it will always melt and pour at approximately 13FC This feature will allow hazardous or radioactive waste specimens that do not pass the required tests to be remelted and reformulated until they do pass. Heavy loadings (5 wt%) of the eight toxic metals have been combined individually with SPC and 7 wt% sodium sulfide nonahydrate (Na,S*9H20). The leach rates for mercury, lead, chromium, and silver oxides were reduced by six orders of magnitude, while arsenic and barium were reduced by four. With ever increasing emphasis on high-temperature treatment of radioactive and hazardous wastes, the ability of SPC to stabilize incinerator ash and its volatilized toxic metal contents is encouraging. AU SPC used in tests to date was formulated for the construction industry. The preceding tests and many others conducted in other countries like Denmark, Japan, France, Germany, and the Netherlands strongly suggest that SPC shows great promise for further development. Ion-exchange resins that failed miserably in routine SPC testing passed in excellent fashion when the temperature and duration of heating was increased. An additive dramatically improved the leach resistance for toxic metals. The search is just beginning for different configurations of SPC that can accommodate higher loadings of various difficult-to-stabilize wastes.
Energy began testing sulfur polymer cement (SPC) as a radioactive and hazardous waste solidification and stabilization agent because of its unusual properties. SPC is a sulfur polymer composite material that begins melting between 110 and 120 degrees C (230 and 248 degrees F), with an optimum pour temperature between 130 and 140 degrees C (266 and 284 degrees F). The compressive strength of SPC upon cooling averages 27.6 MPa (4,000 psi). Its mechanical strengths continue to increase for at least two years to approximately triple the original strength. As a proven construction concrete, SPC has demonstrated the ability to survive for years in acids and salts that destroy or severely damage hydraulic concretes in months or even weeks. Perhaps SPC's strongest selling point is that it will always melt and pour at approximately 13FC This feature will allow hazardous or radioactive waste specimens that do not pass the required tests to be remelted and reformulated until they do pass. Heavy loadings (5 wt%) of the eight toxic metals have been combined individually with SPC and 7 wt% sodium sulfide nonahydrate (Na,S*9H20). The leach rates for mercury, lead, chromium, and silver oxides were reduced by six orders of magnitude, while arsenic and barium were reduced by four. With ever increasing emphasis on high-temperature treatment of radioactive and hazardous wastes, the ability of SPC to stabilize incinerator ash and its volatilized toxic metal contents is encouraging. AU SPC used in tests to date was formulated for the construction industry. The preceding tests and many others conducted in other countries like Denmark, Japan, France, Germany, and the Netherlands strongly suggest that SPC shows great promise for further development. Ion-exchange resins that failed miserably in routine SPC testing passed in excellent fashion when the temperature and duration of heating was increased. An additive dramatically improved the leach resistance for toxic metals. The search is just beginning for different configurations of SPC that can accommodate higher loadings of various difficult-to-stabilize wastes.
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