## 5 Building a Mining Field Exploitation Model--Schedule, Parameterization
Then, the planned sequence of retreating of individual pillars, remaining after the cross-cutting stage, is also introduced. The result of the calculations performed in the schedule will be not only the designation of the end of operation date for the cross-cutting and retreating stage (Figure 7) but also the assignment of the means of transport with the highest value of the objective function for each shift, until the completion of mining works. To calculate the schedule of the progress of mining works, it is also necessary to propose the dates of construction of reloading points on conveyor belts that collect the excavated material transported using wheeled haulage. Thanks to the synchronization of the dates of availability of reloading points with the extraction front, the greatest benefits from the shortening of the tire haulage routes might be achieved. The set of calculation parameters is presented in Tables 2 and 3. The parametric nature of the model should be emphasized; the calculations are carried out based on the geometric dimensions of the mining field, the quantities characterizing various types of means of transport and the method of field exploitation (the level of extraction, mining works on specific days of the week). Figure 7: Planned schedule of mining works in the room and pillar mining system. In the simulation model, the starting dates of the cross-cutting and retreating stage were adopted, bearing in mind that the retreating stage takes place immediately after the cross-cutting. Residual pillars must not lose their load-bearing capacity, decreasing over time, which ensures the stability of the roof. The weekly schedule of mining works includes 4 shifts, five workdays a week and selected working Saturdays. The retreating is not carried out during the night shift, the effective time for mining works was assumed to be \(t_{\textit{eff}}=3.5\) h. The value of the winning density, based on the example of copper ore, was assumed to be 2.32 Mg/m3, it was necessary to recalculate the relation between weight and volume. The production plan \(M_{\textit{plan}}\) took into account the average planned mass of the winning to be transported--obtained from the mine faces--by the stage of cross-cutting and retreating, was 3 615 Mg. A certain extraction fluctuation between the individual months of mining was also introduced (to increase the model's adequacy), the average deviation was approximately 70 Mg. When calculating the schedule, data on the costs of tire haulage for the cross-cutting and retreating stages as well as HC+NOx emissions are collected, as shown in Figure 8. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Geometric Parameters of the Mining Field in the Room and Pillar System 1**} \\ \hline \multirow{2}{*}{parameter name} & \(S_{\textit{ch}}\)—width of the & \(D_{\textit{f}}\)—length of the & \(S_{\textit{f}}\)—width of the & \(i\)—number of & \(j\)—number of & \(\mathrm{crosscuts}\) \\  & drift [m] & pillar [m] & pillar [m] & pillar [m] & corridors & crosscuts \\ \hline value & 7.0 & 7.5 & 15.0 & 32 & 48 \\ \hline \multirow{2}{*}{parameter name} & \(q\)—initial distance & \(h\)—thickness of the & \(\alpha\)—sidewall slope & \(r\)—minimum area of residual pillars [m2] \\  & to the discharge & exploitation & angle [”] & & \\  & point [m] & gangway [m] & & & \\ \hline value & 36 & 3.0 & 10 & 12 & \\ \hline \hline \end{tabular}  
* The data was collected during the R&D project implementation “Adaptation and implementation of Lean in the copper mines”, financed by NCBiR (No. 09-0011-10/2011).  
\end{table} 
Table 2: Summary of computational geometric parameters of the mining field in the room and pillar system for the needs of simulation experiments.