Study on the gelation performance of mechanically wet-activated copper tailings

Copper tailings have high crystallinity and low activity. Previous research on enhancing the activity of copper tailings for their utilization as supplementary materials in concrete and other applications had low utilization rate. This study aims to enhance the utility of copper tailings by activation through mechanical wet grinding and evaluating its gel properties. The activation led to a decrease in the volume average particle size of copper tailings from 43.55 to 17.36 μm, a leftward shift in particle size distribution, an increase in specific surface area, and a rise in reactive surface. The crystallinities of certain mineral phases decreased, with the generation of active sites like ≡Si· and ≡Si–O·, which increased the reactivity from 5.6 to 96.92%. Gelation tests showed maximum reactivity of the tailings after 80 min of wet grinding, with compressive strength reaching 21.31 MPa after 28 days of curing. X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopic (FT-IR) analyses revealed that synergistic activation by mechanical wet grinding resulted in the formation of C-S–H gels, N-A-S–H gels, and ettringite substances in copper tailings, predominantly in flaky, cotton-like, and short rod shapes.