LEACHABILITY OF Pb-DOPED SOLIDIFIED WASTE FORMS USING PORTLAND CEMENT AND CALCITE: III. INSIGHT OF LEACHING
MECHANISM

Lee, Dongjin

doi:2004.9.4.175

Environmental Engineering Research 2004;9(4): 175-183. DOI: https://doi.org/10.4491/eer.2004.9.4.175

LEACHABILITY OF Pb-DOPED SOLIDIFIED WASTE FORMS USING PORTLAND CEMENT AND CALCITE: III. INSIGHT OF LEACHING MECHANISM

Dongjin Lee^†

School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia

Corresponding Author: Dongjin Lee ,Tel: +61-2-9385-5562, Fax: +61-2-9385-6139 , Email: dongj7@empal.com

Received: November 14, 2003; Accepted: August 10, 2004.

ABSTRACT

This study is examined to assess teachability of Pb-doped solidified waste forms using Portland cement and calcite. X-ray diffraction was used for identification of mineral transformations occurring on the solidified waste materials formed during the leaching process. Particular attention is given to the leaching effects of calcite (CaCOj) in the solidification/stabilization of lead. Rapid diffusion of lead substances (K.P20) at the attack of acid is mainly related to dissolution rate of lead precipitates located in larger pores (capillary pores) and their openness in cavities. On the other hand, additional calcite on lead contaminated materials (KC5P20, K.CT0P20) including even a lot of lead precipitates in cavity areas such as KP20 are presumably very resistant to acid attack because enhanced calcium-silicate-hydrate (C-S-H) due to accelerating effect of calcite strongly encapsulates/protects even portlanditc as well as lead precipitates, which not much dissolves even up to the 5*1 leach.

Keywords: Solidification/stabilization (S/S) | Calcite | Lead | X-ray diffraction | teachability