## 3 Empirical Study
### Analysis of Calculation Results  
According to Table 2, when the mining grade increased from 21.04% to 22.36%, the company's revenue increased from CNY 2.42 \(\times\) 104 ten thousand to CNY 2.57 \(\times\) 104 ten thousand, an increase of 10.33%; net cash flow increased by CNY 0.1 \(\times\) 104 ten thousand, an increase of 23.26%; and the economic reliability calculated using the RPEM-based economic reliability model increased from 98.75% to 99.95%, an increase of 1.2%.  
It can be seen that as the ore grade increases, the concentrate production increases, and the profits and net cash flow of the mine also increase. The economic reliability calculated based on the RPEM economic reliability evaluation model is also continuously increasing. This feature is completely consistent with the actual production and operation situation of mining enterprises. This indicates that the economic reliability evaluation model established based on RPEM has its applicability for the economic evaluation of mining projects.  
To more intuitively predict the trend of changes in reliability and revenue, the annual revenue and economic reliability data of enterprises in Table 2 are converted into a curve chart, as shown in Figure 3.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Ore Grade** & \begin{tabular}{c} **Concentrate** \\ **Production** \\ **/\%** \\ \end{tabular} & \begin{tabular}{c} **Income** \\ **/t** \\ \end{tabular} & \begin{tabular}{c} **Net Cash Flow** \\ **/CNY 10,000** \\ \end{tabular} & \begin{tabular}{c} **Reliability** \\ **/CNY 10,000** \\ \end{tabular} & \
\begin{tabular}{c} **Reliability** \\ **Indicators** \\ \end{tabular} &
\begin{tabular}{c} **Economic** \\ **Reliability** \\ **/\%** \\ \end{tabular} \\ \hline
21.04 & 4.21 \(\times\) 105 & 2.42 \(\times\) 104 & 0.43 \(\times\) 104 & 2.2421 & 98.75 \\
21.17 & 4.23 \(\times\) 105 & 2.43 \(\times\) 104 & 0.44 \(\times\) 104 & 2.2759 & 98.84 \\
21.30 & 4.26 \(\times\) 105 & 2.45 \(\times\) 104 & 0.45 \(\times\) 104 & 2.3226 & 98.98 \\
21.43 & 4.29 \(\times\) 105 & 2.46 \(\times\) 104 & 0.46 \(\times\) 104 & 2.3647 & 99.09 \\
21.57 & 4.31 \(\times\) 105 & 2.48 \(\times\) 104 & 0.47 \(\times\) 104 & 2.4031 & 99.18 \\
21.70 & 4.34 \(\times\) 105 & 2.49 \(\times\) 104 & 0.48 \(\times\) 104 & 2.4473 & 99.27 \\
21.83 & 4.37 \(\times\) 105 & 2.51 \(\times\) 104 & 0.49 \(\times\) 104 & 2.4924 & 99.36 \\
21.96 & 4.33 \(\times\) 105 & 2.52 \(\times\) 104 & 0.50 \(\times\) 104 & 2.5292 & 99.41 \\
22.09 & 4.42 \(\times\) 105 & 2.54 \(\times\) 104 & 0.51 \(\times\) 104 & 2.5682 & 99.49 \\
22.22 & 4.44 \(\times\) 105 & 2.55 \(\times\) 104 & 0.52 \(\times\) 104 & 2.6115 & 99.55 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Reliability calculation results.  
Figure 3: Relationship curve between annual revenue and economic reliability with changes in ore grade.  
From Figure 3, it can be seen that as the ore grade increases, the mine income curve and economic reliability curve also change and increase, indicating that while the enterprise income increases, the economic reliability also increases. The trend of curve changes is in line with the objective facts of mine production and operation.  
The empirical research results indicate that the mining economic reliability evaluation model established based on the RPEM method has good applicability, and the evaluation results comply with the basic laws of changes in mining production and operation.