Rheological properties of combustion metamorphic rock slurry for coalfield fire prevention

Coal fire disasters seriously threaten the safety of coal mine production and the surrounding ecological environment. Grouting is an important coal fire control method that involves the sealing of underground cracks and isolation of coal-oxygen contacts. This paper proposes the use of combustion metamorphic rock as a new grouting material to replace loess grouting to resolve the scarcity of loess resources. Stability experiments showed that the slurry syneresis rate increased with increasing water-cement ratio and metamorphic rock content. Mixed slurries with a water-cement ratio of 0.45:1 and slurries containing 20 wt.% and 40 wt.% combustion metamorphic rocks with a water-cement ratio of 0.6:1 were determined to be stable. The addition of cement significantly increased the shear stress of the slurry and greatly improved the rheological properties compared to pure rock slurry. When the water-cement ratio was lower than 0.6:1, the viscosity of the mixed slurry increased with increasing combustion metamorphic rock proportion, whereas the opposite trend was observed for higher water-cement ratios. Based on the stability and rheology of the mixed slurries, the optimal composition was determined to have a 0.6:1 water-cement ratio and 40 wt.% combustion metamorphic rock. The results show that the use of combustion metamorphic rock as a grouting material to replace loess is a viable method for mitigating coal fire disasters. This study provides an important reference for the replacement of loess grouting, which serves to ensure the safety and environmental protection of coal fire areas.

Automated summary

Using combustion metamorphic rock as a grouting material to replace loess is an effective method for mitigating coal fire disasters. It shows good stability and rheological properties, with the optimal composition determined to be a 0.6:1 water-cement ratio and 40 wt.% combustion metamorphic rock.