The backfill mining method is a widely used mining method in the major mines of China, which can maximize the recovery of mineral resources and protect the environment. Currently, major mines in China are starting to build backfill systems to apply the backfill mining method, therefore, Part II reviews the progress China has made on creating backfill systems, of which the main contents include: (1) Composition of the backfill system common in Chinese mines; (2) Typical examples of the backfill system in China. Finally, Part II serves as a guide to begin a conversation, and to encourage experts and scholars to engage in the research of this field.

The stability of mine slopes is an important factor influencing the orderly production of mines and the safety of people’s lives and property. The stability of slopes can be effectively determined by means of three-dimensional simulation analysis. Some 3D simulation analysis methods are based on 2D analysis, and are still essentially 2D analysis methods, whereas this digital simulation analysis uses a true 3D analysis method. This method can reflect the overall slope stability of the mine in a more realistic way, and at the same time, the situation of the selected sections can be observed, making the analysis more scientific and rigorous. This study takes the Shizhuyuan Nonferrous Metal Mine as an example and studies the safety stability of mine slopes through true 3D safety analysis. The results show that the open-pit slopes of the Shizhuyuan mine are stable. The overall model results show that there is only a small amount of tensile damage and no penetration; the section results show that the absolute value of tensile stress is generally small, with a maximum of 1.45 MPa being less than the tensile strength of the material (7.04 MPa). After the model monitoring simulation, it is found that the displacements of each monitoring point are in the process of fluctuation and then stabilisation, which can also indicate that the slope is finally in a stable state. Comparing the above results with the conclusions obtained from the 2D analysis method, the conclusions are found to be in general agreement, indicating that the true 3D simulation analysis method is effective and feasible.

The stability of high and steep slopes in open-pit mines is closely related to the mine operations and the lives of the surrounding residents, so it is important to ensure the safety and stability of the slopes. Hazard classification and stability analysis of high and steep slopes under different working conditions are studied using the Shizhuyuan non-ferrous metal mine from underground to open-pit mining as a typical example. Firstly, data on rock mechanics parameters were obtained through site investigation and sampling. Then, the slope model of the open-pit mine was established and some slopes were selected in the model for qualitative and quantitative analysis. The strength reduction method and the limit equilibrium method were used to calculate the safety factor under each working condition and point out the potential instability areas. The results show that the selected slopes are safe and stable under all working conditions. Finally, on the premise of maintaining the safety and stability of the mine, the final slope angle was optimized from the original 45°21′35″ to 55°30′41″ to reduce production costs and increase mining efficiency. The final open-pit boundary that meets the stability requirements was eventually obtained.