Study on Fluidity and Deposition Characteristics of Air-Containing Filling Slurry.

With the continuous exploitation of global mineral resources, backfill technology for gob areas has become a crucial aspect of mine safety and sustainable development. As a primary method of gob area backfill, slurry backfill directly relates its flow properties and filling height to the efficiency and safety of mine extraction. To enhance the flow properties of the slurry and increase its filling height, a research study on the flow and deposition characteristics of a gas-containing filling slurry was conducted using a combination of theoretical analysis, laboratory experiments, and field tests. Experiments on the gas content were conducted using a concrete gas content tester, rheological property experiments were performed using a paddle rheometer, slump flow tests were carried out using a slump cone, and slurry deposition experiments were conducted using gob area similarity models. Analysis of viscosity characteristics revealed that the slurry gas content increased with the addition of air-entraining agents and the yield stress of the slurry decreased by 49.27% with an increase in the gas content at the same mix ratio, resulting in a 48% reduction in slurry viscosity. By analyzing the mechanism of gas phase enhancement on slurry flow, it was found that the anionic strength of bubbles generated by adding air-entraining agents was greater than the anionic strength within the slurry, changing the original particle arrangement and disrupting the tailings flocculation, thereby increasing the distance between floccules and enhancing the slurry's fluidity. Based on field tests, a semiindustrial flow and deposition experimental platform was established based on similarity theory, which found that the settlement rate of filling slurry with air-entraining agents decreased, improving the expansion ratio. This research is of significant importance for improving the effectiveness of the slurry backfill.