Mitigating Risks in Coal Mining: Simulation-Based Strategy for Oxidation Zone Control Using Inorganic Paste Backfill at the Working Face Corners

Abstract

Insufficient stability of the top plate at the corner of an easily combustible coal seam comprehensive mining face may lead to a natural fire within the goaf. While corner sealing is crucial for minimizing air leakage, current sealing methods struggle to effectively prevent such leakage. Additionally, the distribution characteristics of the oxidation zone in the goaf after sealing are unclear, making it difficult to control the extent of the oxidation zone. To address these issues, a new type of inorganic paste filling material was developed, taking into account the conditions of the Cuncaota II Mine. Various corner-filling schemes were developed, and numerical simulations were used to study the effects of different corner-filling strategies and varying filling interval distances on the width of the oxidation zone in the goaf. Based on these findings, a working face corner-filling technology was proposed and applied to the 22,122 working face. The research results indicate that the mountain sand-based paste filling material, using mountain sand as the filling aggregate and cement and fly ash as the binding materials, not only meets the pumping requirements but also exhibits excellent self-supporting characteristics, thereby addressing the corner filling needs of the working face. The width variation in the oxidation zone in the goaf is influenced by the position and interval distance of the corner filling, showing a pattern of initially decreasing and then increasing with the rise in the filling interval distance, reaching a minimum at a filling interval of 50 m. Field observation data demonstrate that, following the application of the aforementioned filling technology, the width of the oxidation zone in the goaf of the 22,122 working face is reduced by 37.5%, and air leakage decreases by 66.7% compared to the unfilled condition. This technology effectively narrows the range of the oxidation zone in the goaf, ensuring the safety of working face production.