Abstract
The improper disposal of solid wastes could bring great pressures and threats to ecosystem. These detrimental impacts could be reduced or eliminated through solidification/stabilisation technology based on geopolymer. In this paper, composite based geopolymer prepared from coal gangue and blast furnace slag was used for the solidification of heavy metals in lead–zinc tailing (LZT). The impact of various factors on compressive strength development in composite geopolymer was evaluated through response surface experiment. Additionally, the sample with maximum strength (91.13 MPa) was chosen to solidify LZT. The results showed that strength of solidified bodies with addition of 70% LZT fell to 21.68 MPa. Based on leaching tests, these samples could potentially be used for construct applications, since leaching concentrations were far below the standard limits. Heavy metals in LZT were effectively solidified via physical and chemical ways, which was evidenced by chemical speciation analysis, mercury intrusion porosimetry, X-ray diffraction and scanning electron microscope with energy dispersive spectrometry analyses.
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