Abstract
The transition from open pit mining to underground mining is essential for mineral resources to achieve deep excavation. Recently, cemented paste backfill (CPB) has been proposed as a novel technology to achieve open pit backfill (OPB). The proposed method not only eliminates the danger of the open-pit slope but also reduces the disposal of waste tailings. In order to ensure safe mining during the synergetic operation of OPB and underground mining, it is of great significance to improve this technology. In the present study, an open-pit metal mine in Anhui Province was taken as the research object. Then, the safety of underground stope roofs, underground backfill pillars, and open-pit slopes was evaluated during OPB. To this end, numerical simulations were performed and experiments were conducted on a similar physical model. Accordingly, the backfill mechanical parameters were optimized. The obtained results show that backfill height exerts the most significant effect on the safety of roofs and underground backfill pillars, accompanied by small displacements along the vertical direction during the backfill process. Moreover, concentration was observed at the foot of the slope, while the overall structure remained stable with no considerable displacement. The overall safety factors met the safety requirements. Based on the obtained results, the optimal foundation strength, foundation height, backfill strength and backfill height were 4 MPa, 10 m, 1.5 MPa, and 120 m, respectively. Moreover, it was concluded that displacements in the abovementioned three regions tend to be stable when the backfill height exceeds 150 m without damage. The present article provides a certain theoretical and application guideline for OPB practices in similar metal mines and suggests possibilities for cleaner production.
Highlights
IntroductionConsidering reasonable economic parameters (such as stripping ratio) in the mining industry, it is crucial to transition from the open pit to the underground mining after reaching the ‘great depth’ in open-pit metal mines [1]
Further investigations reveal that the open pit caused by the open-pit mining threatens the local environment, but the created puddle affects the safety of the underground mining
The safety and stability during the process of open pit backfill (OPB) are verified by physical model tests
Summary
Considering reasonable economic parameters (such as stripping ratio) in the mining industry, it is crucial to transition from the open pit to the underground mining after reaching the ‘great depth’ in open-pit metal mines [1]. Such conversion can make full use of existing infrastructures and equipment to facilitate the excavation of ore deposits, which is of great significance for the sustainable development of metal mines. It increases occurrence probability of collapses and landslides (Figure 1a), thereby becoming a major source of safety hazards during the normal operation of metal mines [2]
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