Solidification/stabilization of a heavy metal sludge by a Portland cement/fly ash binding mixture
A Portland cement/Class F fly ash binder was used to solidify a heavy-metal sludge containing Cr, Ni, Cd, and Hg. The cement/fly ash ratio was 0.4, and the sludge/solids ratio was 1.43. Samples were cured at room temperature for a minimum of 28 days, then examined by scanning electron microscopy, energy dispersive x-ray spectrometry, optical microscopy, and x-ray diffractometry. The sludge was composed of the hydration products of cement/fly ash mixtures, and impure, complex compounds of the waste metals. The sludge formed a simple mixture with the binder, retarded hydration, and affected microscopic phase composition; calcium hydroxide did not form. Reaction products near the surfaces of fly ash particles contained minor amounts of Cr and Ni, suggesting some chemical stabilization of these toxic metal ions.
Publication Source (Journal or Book title)
Hazardous Waste and Hazardous Materials
Roy, A., Eaton, H., Cartledge, F., & Tittlebaum, M. (1991). Solidification/stabilization of a heavy metal sludge by a Portland cement/fly ash binding mixture. Hazardous Waste and Hazardous Materials, 8 (1), 33-41. https://doi.org/10.1089/hwm.1991.8.33