Effect of Microbially Induced Carbonate Precipitation (MICP) via Denitrification on the Dissolution Rate and Stability of Gypsum Mine Pillars: Laboratory Scale Experiments

Document Type

Article

Publication Date

1-1-2025

Abstract

Gypsum mine pillars in flooded abandoned mines are susceptible to water dissolution, particularly when flowing groundwater is encountered. Over time, this dissolution of gypsum weakens the pillars and increases the risk of collapse. Traditional stabilization methods, such as grouting and structural reinforcement, have limitations in terms of cost, feasibility, and environmental impact. This study investigates the potential of a nature-based biocementation method, i.e., Microbially Induced Carbonate Precipitation (MICP) via denitrification, as an alternative approach to enhance the stability of gypsum mine pillars. Laboratory experiments were conducted to evaluate the effects of MICP treatment on gypsum cores subjected to varying water flow rates. Samples were treated with different treatment cycles and two main treatment procedures (submerging and spraying), and their resistance to dissolution was evaluated. The results of the submerging method showed promising results, indicating that MICP treatment can decrease the dissolution rate of the gypsum pillar. The results also showed that increasing the number of MICP treatment cycles significantly reduces gypsum dissolution and the unconfined compression strength of dissolved samples. Scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed that the calcium carbonate precipitated as calcite, forming a protective crust that mitigates dissolution. The results of the spraying method were not satisfactory, possibly due to fast evaporation of water from the surface of treated samples.

Publication Title

Rock Mechanics and Rock Engineering

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