Microorganisms · Published 2026-07-30 · DOI 10.3390/microorganisms14081675
Zhongqun Guo, Yukun Zhong, Jianqi Wu, Qiangqiang Liu, Xi Cao
Ion-type rare earth tailings are mechanically weak and may release Pb and Zn, posing both geotechnical and environmental risks. Basalt-fiber-reinforced microbially induced carbonate precipitation (BF-MICP) was investigated as a combined solidification/stabilization treatment for these tailings. By integrating peak and post-peak mechanical responses, heavy-metal leaching, the spatial distribution of calcium carbonate (CaCO<sub>3</sub>), and microstructural characterization, this study distinguishes the respective contributions of microbial mineralization and fiber reinforcement. Tailings specimens were treated with basalt fiber contents ranging from 0 to 0.8% and evaluated using unconfined compression tests, leaching tests, CaCO<sub>3</sub> measurements, X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive spectroscopy. The unconfined compressive strength first increased and then decreased with increasing fiber content, reaching 1.72 MPa at 0.4% fiber, approximately 90% higher than that of the MICP-only group. At the same fiber content, compressive total energy absorption increased from approximately 18 to 68 kJ·m<sup>−3</sup>, indicating a marked improvement in post-peak toughness. BF-MICP treatment increased the CaCO<sub>3</sub> content to approximately 2–3 times that of untreated tailings, although the deposits remained more abundant in the outer region than in the core, and the total CaCO<sub>3</sub> content varied little with fiber dosage. The leached concentrations of Pb and Zn decreased by 79–81% and 81–84%, respectively, with no clear additional reduction as the fiber dosage increased. Microstructural analyses showed that calcite-dominated deposits connected tailing particles and fiber surfaces. These results indicate that MICP primarily governed mineral cementation and heavy-metal immobilization, whereas basalt fibers mainly improved load transfer, crack bridging, and post-peak structural integrity. A fiber content of 0.3–0.4% provided the best overall balance between mechanical performance and leaching control.
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Guo, Z., Zhong, Y., Wu, J., et al. (2026). Mechanical Properties and Leaching Characteristics of BF-MICP Solidified/Stabilized Ion-Type Rare Earth Tailings. Microorganisms. https://doi.org/10.3390/microorganisms14081675