Transition and continuation scheme of open-pit mining area under complex engineering geological conditions

When large-scale near-level coal field adopts open-pit mining, in order to realise safe and efficient production and recover the investment cost as soon as possible, it usually adopts the way of mining in sub-districts, so before the old mining area is about to reach the boundary, it is inevitable to consider the problem of the transition succession between the old and new mining areas. Therefore, before the old mining area reaches the boundary, the issue of the transition between the old and new mining areas must be considered. The formulation of a turning plan for an open-pit coal mine mining area is related to the smooth transition of production capacity during the turning period, which directly affects the economic benefits of the mine. In actual production, some mines are limited by issues such as the land acquisition system, mining intensity, and complex geological conditions, which force open-pit coal mines to turn early. Research has shown that by adjusting key parameters such as the length and advancement speed of the local working line during the turning period, the stripping and mining plan during the turning period can be optimized to ensure a smooth transition of the mine. Due to the serious deformation of the east side of the north bench of the Baiyinhua No.1 open-pit coal mine, the first mining area was forced to shift to the second mining area ahead of schedule in order to ensure the smooth continuation of production capacity. However, the land acquisition for the second mining area was limited, and the gentle bench working line could not be fully deployed, resulting in changes to the original mining procedures. In order to ensure the smooth transition of the first mining area to the second mining area of Baiyinhua No. 1 Open Pit Coal Mine, an improved method of transition and connection for the L-shaped working line mining area is proposed, and on this basis, the constraint relationship between the length and advancement of different working lines is clarified. Through engineering simulation, it is determined that the transition period from the first mining area to the second mining area of Baiyinhua No. 1 Open Pit Coal Mine is 6 years; the amount of coal that can be mined during the transition period is 72.9407 million tons, the amount of overburden removed is 431.4129 million m³, with a stripping ratio of 5.91 m³/t. The research results provide sufficient technical support for the transition from the first mining area to the second mining area of the Baiyinhua No. 1 open-pit coal mine, and provide relevant experience for the transition and connection of open-pit mining areas under complex engineering geological conditions.