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The delineation of the open-pit mining boundary, particularly in the context of medium to long-term planning, forms the foundation of mining design. However, due to the non-linear and dynamic nature of the economic and technical parameters influencing boundary delineation, determining the optimal mining boundary can be exceedingly challenging. Currently, most boundary optimization methods assume that block parameters remain fixed, which results in enterprises assuming a certain level of risk when facing changes in internal and external conditions. In this regard, this paper introduces the concept of "achievement degree" to reflect the risk associated with the results of boundary design. Using coal prices as an example, this article applies the predicted coal price curve to boundary optimization adjustments by specifying the "achievement degree" requirements for various time periods, thereby facilitating risk-controlled and economically optimal boundary decisions. Taking the illustrative case of an idealized small-scale inclined coal seam open-pit mine, adjustments to the boundary closely track variations in coal prices, further enhancing returns. The results demonstrate that the method proposed in this paper can increase overall revenue by approximately 51.15% within the forecast period, while effectively managing risks. [ABSTRACT FROM AUTHOR]

In the initial production phase of an inclined seam opencast mine, due to initial investment and production capacity constraints, zoning or phasing is usually used, resulting in changes in the length of the working line during the transition of the mining area. To simplify the process, this article analyses the changes in the length of the working line during the period of slow gang steering in inclined seam opencast mines. In order to simplify the process, this article analyses the changes in the length of the working line in each period. The relationship between the length of the working line and the realm stripping ratio in the overlapping area of the two mining areas is discussed, and the variation in the realm stripping ratio and the economically reasonable stripping ratio under different working line lengths is illustrated. The advantages and disadvantages of the different optimization options are described. The optimization method was applied to the Zhundong opencast coal mine to calculate the working line lengths for the two stages. The optimized stripping ratio for the second-stage south gang location is equal to the economically reasonable stripping ratio of 3.50 m3/t, which reduces coal compression and improves economic efficiency, and is a guideline for the study of the working line lengths in each stage of the open-pit mine slow gang turning. [ABSTRACT FROM AUTHOR]

In view of the inclined occurrence of coal seam in Heishan open-pit coal mine, in the longitudinal exploitation process of the first mining area, the height of the slope at the west end is increasing, and the occurrence of weak interlayer in the slope is in production. The failure mechanism and stability of the end slope of the inclined composite coal seam, which is typical of the West end slope of Heishan open-pit mine, are studied by means of field investigation, theoretical analysis, limit equilibrium analysis, and numerical simulation. The factors affecting the stability of the western side slope and the potential landslide mode are analyzed. The residual thrust method and simplified Bishop method were used to study the stability of two potential landslide modes on the western slope, and the landslide mode, final slope angle, and slope morphology were determined. FLAC3D was used to simulate the western end of the slope, reveal its landslide mechanism, and clarify the evolution law of the slope rock mass displacement. The results show that the landslide mode at the west end of the first mining area is the combined sliding mode of "cutting and bedding." With the decrease of longitudinal mining depth, the final slope angle functions from 40° to 37°. The stress and strain are concentrated at the weak layer of the coal floor of the western side slope 13-2 and at the foot of the slope. Meanwhile, the failure also occurs inside the slope. The internal cracks connect through the weak layer of the coal floor and slide along the weak layer of the coal floor 13-2. The displacement evolution law of the slope monitoring point shows that the deformation of the slope is mainly horizontal displacement, the maximum displacement deformation is at the foot of the slope, and the degree of displacement deformation of the slope surface is obviously greater than that of the inside of the slope. [ABSTRACT FROM AUTHOR]