Dredged-sediments increased to about 15million m2 from 1998 to 2012 by port construction, sediment reclamation and dredging business. Most of dredged-sediments which are generated in Korea have been treated by Marine dumping. However, there are increasing concern about contamination by heavy metals in dredged-sediments. Therefore, it is required to remove heavy metals from dredged-sediments.
The purpose of this study is to remove zinc from domestic dredged sediments contaminated with ZnS using ferric chloride.
Consequently, leaching behavior of zinc was investigated under the following leaching conditions 400rpm, 80℃ and 0.5M FeCl3 in 1M HCl, and content of zinc in residue decreased to 184mg/kg which meet Marine dumping regulations(Zn:200mg/kg).
The shrinking core model(Ash diffusion controlled) was investigated based on the leaching results. Correlation coefficients were closed to 1 so that model best fitted to the kinetic data. The activation energy for the leaching process was found to be 64.1-76.9kJ/mol for 1-0.25M FeCl3 respectively, and that means leaching precess depends on chemical reaction. 40 and 90℃ in temperature, 0.25-1M in concentration of ferric ion, 5-20% in pulp density, and 200-600rpm in stirring speed. Leaching efficiency of zinc increased with leaching temperature and ferric ion concentration. The leaching efficiency was 96.7% under the following conditions