Reduction/immobilization of chromite ore processing residue using composite materials based geopolymer coupled with zero-valent iron

Abstract

Chromite ore processing residue (COPR) is a hazardous waste due to the presence of highly mobile Cr(VI). In this paper, the reduction/immobilization of COPR using composite materials (fly ash, blast furnace slag and metakaolin) based geopolymer coupled with zero-valent iron (ZVI) was investigated. The effects of ZVI and acid dosages on the reduction of Cr(VI) in COPR had been analysed. The immobilization of original COPR samples and reduced COPR samples were prepared. The immobilization effect was evaluated by compressive strength and leaching tests. The results showed that geopolymer with reduced COPR had better immobilization effect as compared to original COPR. According to mechanical and leaching properties of geopolymer with reduced COPR samples as well as X-ray diffraction, scanning electron microscope with energy dispersive spectrometer and Fourier transform infrared spectrometry analyses, COPR was effectively immobilized.