• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1138-1142
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• 2002

Slag cement and supersulfated slag cement were fabricated by mixing blast furnace slag and ordinary portland cement and adapted to solidify/stabilize heavy metal contained hazardous waste sludge. In case of slag cement, it showed continuous increase of their compressive strengths, which is attributed to the formation of the C-S-H, ettringite and monosulfate with STS sludge. However, BF and COREX sludge has a different shape and composition. therefore, adequate compressive strength could not be achieved with this slag cement. In case of the mixture of the each sludge like the STS-BF or the STS-COREX, the compressive strength over the standard level for disposing the wastes could be obtained with slag cement. The supersulfated slag cement that contain accelerators was very effective in solidifying the COREX sludge, which was difficult to solidify using different cement and obtained high compressive strength only for 3 days.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1133-1137
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• 2002

The cement for solidification of the toxic waste was fabricated using a mixture of the waste concrete powder and blast furnace slag in the ratio of 1:1 and its hydrate morphology and compressive strength of the sample were evaluated in order to apply to the solidification of the COREX sludge. The X-ray diffraction analysis of the sample which prepared by the addition of 10% Portland cement and hemihydrate showed the presence of $Ca(OH)_2$, ettringite, gel-phase and C-S-H hydrate. Compressive strength of the sample exhibited enough high to use as a solidification cement. The strength of the sample was over 140 kgf/$m^2$ in 7 days in case of solidification of the COREX sludge and the sample possess sufficient morphology for the solidification and stabilization of the waste sludge.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.680-686
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• 2002

The solidification/stabilization mechanism of each cementious material was investigated. It was found that when $C_3$S was hydrated , the Pb element could be transferred to the insoluble Ca[Pb(OH)$_3$.$H_2O$]$_2$and the Cr element to the CaCr $O_4$$H_2O$. The addition of heavy metal tends to delay the hydration until initial 7 days. The Pb element as also delayed the hydration and the Cr element was substituted for the ettringite. On the occasion of the hydration of $C_4$ $A_3$ $S^{S}$, the Pb and Cr ions were solidified/stabilized by the substitution into the ettringite and/or monosulfate. Leaching of the Pb, Cr and Zn elements in the solidified material was extremely little, indicating that heavy metals were effectively solidified/stabilized in the hydrated cementious materials. Solidification/stabilization of heavy metal ions in the industrial wastes such as the STS, BF and COREX sludge was investigated. In case of the mixing ratio of cement and slag was 3 : 7, leaching of hazardous heavy metal ions was very little, indications that the solidification and stabilization was very successful.l.