## 4 Flow Field Analysis of Corner-Filled Goaf Area Using ANSYS Fluent
### Application of Inorganic Paste Filling Technology at Working Face Corner  
(1) Process Flow for Filling Workforce Corners  
According to the analysis presented earlier, a filling scheme is chosen for the corner-filling operation of the 22,122 comprehensive mining face. This scheme involves filling both corners at intervals of 50 m. The key steps in the inorganic paste filling technology process for the 22,122 working face corner include the preparation and transportation of filling materials, the installation of mobile filling pumps, the laying of pipelines, the pumping of inorganic paste filling slurry, and other critical steps. Taking into account the actual mine conditions, the filling operation for the working face corners is carried out using the surface slurry preparation and tanker transportation method. The specific implementation process is depicted in Figure 17.  
2. Results and Analysis of Corner Filling in Working Face 22,122  
Through the processes of preparing ground slurry, transporting it via a mixer truck, and pumping it through pipelines, the inorganic paste slurry is efficiently pumped to specified locations at the two corners of the working face for filling. Once the filling process is concluded, overflow of the filling slurry at the top of the caved rock layer is observed, and it is depicted in Figure 18. Following two filling sessions, each at a 50 m interval for the two corners of the working face, air leakage before and after the filling is assessed using SF6 gas, employing a system of marking and tracking. SF6 tracing gas is released in the intake airway, and in the presence of air leakage in the working face, the SF6 concentration at measurement points along the path exhibits a decreasing trend. The leakage amount \(\Delta\)Q between two sampling points can be computed using Equation (5) [35]. The distribution of release points and sampling points is visually represented in Figure 19. Under the measured ventilation rate condition of 1279 m\({}^{3}\cdot\)min\({}^{-1}\) in the working face, the analysis of SF6 concentrations at sampling points 1 and 3 indicates that the air leakage amount \(\Delta\)Q before filling is 147 m\({}^{3}\cdot\)min\({}^{-1}\). Post-filling, the leakage amount \(\Delta\)Q decreases to 49 m\({}^{3}\cdot\)min\({}^{-1}\), marking a notable reduction of 66.7%. The majority of post-filling air leakage is directed into the goat behind the hydraulic support, significantly diminishing air leakage at the two corners of the working face compared to the unfilled state. \[\Delta Q=\frac{q(C_{1}-C_{2})}{C_{1}C_{2}} \tag{5}\]  
where \(q\)--amount of released SF6 gas, mL/min; \(C_{1}\)--SF6 concentration after analysis in the intake airway, ppm; and \(C_{2}\)--SF6 concentration after analysis in the return airway, ppm. Figure 17: Surface pulping inorganic paste filling system. After conducting two filling and sealing operations at the corners of the working face, gas samples were systematically collected from the intake and return airway ducts, with close monitoring of their compositions. The obtained gas concentrations were then carefully compared to those measured before the filling process, as detailed in Figure 20. As shown in Figure 20a, after the filling and sealing procedures at the corners of the working face, the oxygen concentration on the intake side of the goat decreased to 15% at a distance of 145 m from the working face, indicating entry into the oxidation zone. Furthermore, it decreased to 5% at a distance of 200 m, entering the asphyxiation zone. In comparison to the pre-filling conditions, the width of the oxidation zone in the goat significantly reduced from 95 m to 55 m, reflecting a noteworthy decrease of 42%. Shifting attention to the return side of the goat, as depicted in Figure 20b, post-filling, the oxygen concentration within the goat declined to 15%, entering the oxidation zone at a distance of 39 m from the working face, and it further dropped to 5% at a distance of 135 m, entering the asphyxiation zone.