# Study on the Determination Method of Cast Blasting Stockpile Forms in an Open-Pit Mine
## 4 Discussion  
To verify the reliability of the fitting results of the cast blasting stockpile profile, we adopted interval estimation as a verification method and verified the cast blasting stockpile profile under the conditions of 35 m, 40 m, and 45 m cast blasting steps. The effective throwing rate, the material quantity of the upper layer, and the material quantity of the coal trench were taken as verification indexes. The fitting results were verified by testing whether the three satisfied the confidence of the confidence interval. The data error should be reduced as much as possible, so the interval length \(L\) should be maximized as much as possible to improve the selection accuracy of the interval of the detonation morphology. In this study, \(\alpha\) = 0.05 (\(z_{\frac{\alpha}{2}}=z_{0.025}=1.96\) from the table) was selected, and the confidence of the basic index was 95%. 1. Statistical analysis of samples with a 35 m step height  
By referring to the calculation principle and the process of interval estimation, the confidence interval of the fitting results of the effective throwing rate, material quantity of the upper layer, and the material quantity of the coal trench at a 35 m high cast blasting step were obtained, as shown in Table 8.  
According to the fitting results of the cast blasting stockpile profile with the height step of 35 m, the effective throwing rate of the cast blasting stockpile profile is 34.9%, the material quantity of the upper layer is 1098.2 m\({}^{2}\), and the material volume of the coal trench is 422.8 m\({}^{2}\), satisfying the above confidence interval. Therefore, the shape-fitting result of the cast blasting stockpile form is basically consistent with the actual cast blasting stockpile form. 2. Statistical analysis of samples with a 40 m step height  
Similarly, the confidence interval of the fitting results of the effective throwing rate, the material quantity of the upper layer, and the material quantity of the coal trench with a 40 m high cast blasting step were obtained, as shown in Table 8.  
According to the fitting results of the cast blasting stockpile profile with the height step of 40 m, the effective throwing rate of the cast blasting stockpile profile is 33.1%, the material quantity of the upper layer is 1408.3 m\({}^{2}\), and the material volume of the coal trench is 482.8 m\({}^{2}\), satisfying the above confidence interval. Therefore, the shape-fitting result of the cast blasting stockpile form is basically consistent with the actual cast blasting stockpile form. 3. Statistical analysis of samples with a 45 m step height  
Similarly, the confidence interval of fitting results of effective throwing rate, the material quantity of the upper layer, and the material quantity of the coal trench with a 45 m high cast blasting step were obtained, as shown in Table 8.  
According to the fitting results of the cast blasting stockpile profile with the height step of 45 m, the effective throwing rate of the cast blasting stockpile profile is 33.8%, the material quantity of the upper layer is 1438.7 m\({}^{2}\), and the material volume of the coal trench is 554.2 m\({}^{2}\), satisfying the above confidence interval. Therefore, the shape-fitting result of the cast blasting stockpile form is basically consistent with the actual cast blasting stockpile form. 5. Conclusions  
Unlike the conventional prediction of the cast blasting stockpile form, we have presented a method to determine the cast blasting stockpile form based on field production practice data. Using research with the Heidaigou open-pit mine as an example, through an analysis of field data acquisition, reconstruction of form, and combining the building of digital model dragline stripping steps, strict screening can reflect the real blasting effect of the sample database and then use the locally weighted regression method for current screening after fitting the sample data to the cast blasting stockpile form.