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Distributions of Cr, Ni, Cu and Zn in Hazardous Waste Co-Processing in a Pilot-Scale Rotary Cement Kiln

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Author(s): Jenwit Krobthong | Manaskorn Rachakornkij | Viboon Sricharoenchaikul

Journal: Journal of Applied Sciences
ISSN 1812-5654

Volume: 12;
Issue: 1;
Start page: 22;
Date: 2012;
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Keywords: pilot-scale rotary cement kiln | heavy metals | co-processing | Hazardous waste management | portland cement clinker

ABSTRACT
Cement kiln can be used for both destruction of hazardous organics and stabilization of heavy metals. This method provides alternative materials as raw materials or the fuel in the cement production process. However, the heavy metals in waste made the effect to cement properties. This study investigated the chemical and physical characteristics of various mixtures of cement clinker. Raw materials were mixed with different ratios of oxides of heavy metals: Namely, Cr (Cr2O3), Cu (CuO), Ni (NiO2), Zn (ZnO) for combinations of four kinds of heavy metals were between 0.05 to 2.0%. The mixtures were burned in a pilot-scale rotary cement kiln which the liquid petroleum gas fired. The results showed that the concentration of heavy metals in the clinker was higher than in the mixtures before combustion. Moreover, the heavy metals were not destroyed in the burning process and the crystals of heavy metals appeared in the clinker which were trapped to the C2S, C3S, C3A and C4AF. Improvement of early strength at the 1 day for 0.05% wt. of combination of heavy metals was more than 130 kg cm-2. The compressive strength at the 28 days of the clinker contained 0.05 and 0.3% wt. of combination of heavy metals were more than 400 kg cm-2. However, the leaching test have shown that the all of different ratio of heavy metals in clinker and cement mortar still in the range when compared with Thai standard. High concentration of heavy metals increased percent free lime but decreased percent C3S.
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