Experiments were conducted to investigate the effects of bacterial solution concentration and pH on calcium carbonate production and the bioflocculation lag period during microbially induced carbonate precipitation (MICP) reinforcement of tailings sand. The effectiveness of this method in reinforcing tailings sand was evaluated using tests for permeability

water retention

resistance to raindrop erosion

wind erosion resistance and penetration. By analyzing the influence of pH on urease activity and the equilibrium of the carbonate system

and observing the microstructure of tailings sand through scanning electron microscope and X-ray diffraction tests

the mechanism of MICP reinforcement of tailings sand at low pH was revealed. Results showed that the MICP method at low pH significantly improved the mechanical properties of tailings sand. After a single spray treatment

the wind erosion mass of tailings sand was reduced to zero

and the permeability coefficient decreased by an order of magnitude. Additionally

the raindrop and wind erosion mass of tailings sand treated with a high-concentration bacterial solution at pH = 4 was also reduced to zero. Low pH temporarily inhibited urease activity and disrupted the carbonate system equilibrium

delaying calcium carbonate precipitation. This allowed calcite to uniformly fill the intergranular pores of tailings sand

cementing the sand particles together. This research presents a novel approach to tailings dam reinforcement and tailings sand treatment

elucidating its reinforcement mechanism and offering theoretical and experimental support for the application of low-pH MICP reinforcement of tailings sand.