Preparation of geopolymers from vanadium tailings by mechanical activation

Because the vanadium tailings (VT) obtained from vanadium extraction are regarded as waste material with a low reuse rate, the recycling of VT is environmentally desirable and economically feasible. The main objective of this work was to investigate the feasibility of preparing geopolymers from low-reactivity and silica-rich VT by employing a new method, called mechanical activation (MA). The changes in the physicochemical properties and structure of the tailings before and after MA were explained by the determinations of particle size distribution, specific surface area, and the content of reactive components, as well as X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). A calorimetric study was conducted to observe the geopolymerization process. The effect of MA on the resulting geopolymers was characterized by setting time, compressive strength, and resistance to chemical attack. The results show that MA is an effective method to improve the reactivity of the VT for geopolymer preparation. The maximum compressive strength of the activated-tailing based geopolymer (25 MPa) surpassed the strength (8.7 MPa) of the geopolymer based on the raw VT. In addition, activated geopolymers showed shorter setting times and better resistance to chemical attack.