Recycling vanadium-bearing shale leaching residue for the production of one-part geopolymers

Abstract

Each year, the extraction of vanadium from vanadium-bearing shale generates a significant amount of mine tailing. Vanadium-bearing shale leaching residue (VSLR) not only occupies lots of land, but also poses serious threat to the surrounding environment. In this study, the VSLR was recycled as construction materials based on geopolymerization. Metakaolin was supplied as aluminum source material. The reactive activity of VSLR and metakaolin were evaluated by leaching test. The effect of factors, such as VSLR contents, water-to-solid ratios and curing temperature, on the compressive strength of geopolymer were discussed. The phase compositions of VSLR-based geopolymer was studied by x-ray diffraction (XRD) analysis, and the bond structure of geopolymer was investigated by the Fourier-transform infrared spectroscopy (FTIR) analysis, and the microstructure was investigated by scanning electron microscopy (SEM) imaging. The results show that VSLR containing part of soluble silicon component, and could be used as silicon source materials. The VSLR contents have profound effects on compressive strength, and the unreacted VSLR particles acted as aggregate. The water-to-solid ratio affects not only mechanical properties, but also the workability in application. Curing temperature mainly affects the early stages of geopolymerization, and the effects gradually weaken with the curing age prolonged.