Compressive strength characteristics and mechanism of tungsten tailings activated by multi concentration alkali

Abstract

The 7d unconfined compressive strength tests of alkali-activated tungsten tailings and the microscopic characteristics tests of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were conducted to investigate the variation law and mechanism of unconfined compressive strength of alkali-activated tungsten tailings under the conditions of seven alkali-solid ratios with the same moisture content. The test results indicate that the unconfined compressive strength of alkali-activated tungsten tailings is increased with the alkali-solid ratio. However, the strength decreases slightly when the alkali-solid ratio is 12%. Alkali activation does not change the crystal type on the micro-scale but forms gels including C-A-S-H and N-A-S-H. The microstructures of the gel are affected by the alkali-solid ratio: The microstructure is honeycomb in low alkali-solid ratio (7%, 8% and 10%), with N-A-S-H as its primary form, and flocculation in high alkali-solid ratio (14% and 15%), mainly in the form of C-A-S-H. When the solid alkali ratio is at the medium level (12%), the microstructure is a small round bead, and the N-A-S-H is equivalent to the C-A-S-H. The generation of C-A-S-H and N-A-S-H gels is the key to increase the strength of alkali activated tungsten tailings. The more C-A-S-H content, the greater the strength. This study can provide a scientific basis and technical reference for the resource utilization of tungsten tailings.