Experimental study on the disintegration characteristics of rare earth tailings improved by BF-MICP

The disintegration resistance of building foundation filling materials is directly related to the stability, safety, and durability of geotechnical engineering. Improving the disintegration characteristics of tailings is of significant importance for the comprehensive utilization of tailing waste. This study adopts basalt fiber (BF) and microbial induced carbonate precipitation (MICP) technology in combination (BF-MICP) to improve the typical rare earth tailings from South China. A systematic evaluation of the disintegration resistance of the modified tailings under wet-dry cycling conditions is conducted. Using a self-made test device, disintegration tests on the rare earth tailings under different modification conditions were carried out, and the effects of MICP treatment and fiber content on disintegration time and disintegration rate were analyzed. Microstructural analysis techniques such as XRD, FTIR, SEM, and EDS were employed to reveal the microscopic mechanism of the BF-MICP modification of the rare earth tailings. The results show that the addition of BF alone only slightly delays the disintegration process. Compared to unmodified tailings, the disintegration time of BF-modified tailings is extended to 940–1080 s, and the maximum mass loss per unit time is reduced to 6.1%–8.5%. However, it does not fundamentally inhibit the disintegration of the tailings upon contact with water. After BF-MICP treatment, the disintegration resistance of the tailings is significantly improved. The BF-MICP tailings maintain structural integrity after 4800 s of immersion, with the disintegration rate significantly reduced to 32%–45%. Moreover, the treated tailings retain good integrity after multiple wet-dry cycles.