# Study on the Macro-Fine Mechanical Behavior of Ore Flow Based on the Discrete Element Method
## 5 Conclusions  
Based on the discrete element analysis method, the flow characteristics, the mechanical evolution mechanism of the ore-rock particles in the ore-drawing process, and the stress characteristics of the wall of the ore-pass storage section are studied. A method for characterizing the damage degree of the ore-pass wall using the overpressure coefficient and overpressure frequency is proposed. The main conclusions of this study are as follows:  
The important factors affecting the ore-rock's macroscopic flow pattern are the friction between ore-rock particles, particles, and the shaft wall, and the constraint of funnel boundary. In the ore-drawing process, the macro-shape of rock particles with different flow rates gradually changes from a \"--\" shape to a \"U\" shape, and finally, a \"V\" shape is drawn out.  
The study of coordination number variation characteristics between ore-rock particles shows that under the different ore-drawing times, the average coordination numbers  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Region** & \begin{tabular}{c} **Measurement Point** \\ **Number** \\ \end{tabular} & \
\begin{tabular}{c} **Number of** \\ **Overpressure/Time** \\ \end{tabular} &
\begin{tabular}{c} **Maximum** \\ **Overpressure Factor** \\ \end{tabular} \\ \hline Lower part of the storage section & 1 & 15 & 6.4 \\  & 2 & 0 & 0 \\  & 3 & 3 & 1.42 \\  & 4 & 1 & 1.07 \\  & 5 & 1 & 1.16 \\  & 6 & 1 & 1.21 \\  & 7 & 1 & 1.06 \\  & 8 & 0 & 0 \\  & 9 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Overpressure data of each measurement point under different ore-drawing times.  
between ore-rock particles near the bottom of the ore pass are larger than that in the upper part of the ore pass. When the ore is drawn 5 times, the average coordination number of measuring circles No. 1-6 (near the bottom of the ore pass) increased from 3.41 times to 3.87; after ore drawing 10 times, it increased to 3.85; and the average coordination numbers measured by measuring circles No. 7-18 (located in the upper part of measuring circles No. 1-6), depending on the position of the measuring circle, decreased continuously from the top to the bottom, until they were 0. This causes the density and stress concentration to become more and more obvious, and the range of the high-stress concentration area decreases with the decrease in the total amount of stored ore-rock. The shaft wall and funnel at the bottom of the storage section are under the action of high stress, which makes it easy to produce a large number of fine cracks, causing damage to the ore-pass wall.  
With the increase in the ore-drawing times, the probability distribution of the contact force strength decreases exponentially. The strong and weak force chains in the ore-rock bulk constantly break and transfer under the action of ore-rock flow, and the number of ore-rock particles contained in the weak force chains gradually increased, while that in the strong force chains gradually reduced. However, the strong force chains play a leading role in ensuring the stability of the whole bulk structure system.  
Methodology, software, formal analysis, data curation, writing--original draft, funding acquisition, Z.X.; Software, investigation, resources, data curation, Z.D.; Conceptualization, methodology, formal analysis, writing--review and editing, project administration, funding acquisition, Z.L.; Resources, data curation, visualization, supervision, C.M. All authors have read and agreed to the published version of the manuscript.  
The work was supported by the National Natural Science Foundation of China (Grant No. 52204137, Grant No. 51774176), the Natural Science Foundation of Liaoning Province (Grant No. 2022-BS-281), and the Outstanding Young Scientific and Technological Talents Project of Liaoning University of Science and Technology (Grant No. 2023 YQ10).  
The detailed data are available upon request. The data are not publicly available due to privacy.  
The authors declare no conflicts of interest.