75 / 2021-11-30 13:30:11

Numerical investigation on stratum and surface deformation of underground phosphorite mining with different mining methods

phosphorite underground mining,roof deformation,surface subsidence,cement backfill mining,slope stability,different mining methods

Resource Development and Utilization > 3. New Theory and Technology of Deep Resource Exploitation

With the ending of deep-concave open-pit phosphorite extractions and the gradual exhaustion of shallow mineral resources, phosphorite mines have entered or will enter into underground mining. Particularly for excavating slightly inclined thin and medium-thick phosphorite orebody, roof and surface deformation control under different mining methods is crucial for safe and effective exploitations. In this paper, taking the Kunyang Mine with slightly inclined thin and medium-thick phosphorite as the engineering background, based on the occurrence conditions, orebody thickness, dip angle, etc., the mining methods of underground phosphorite are selected, including the room and pillar method, the cement backfill method and the caving method. Numerical analysis on the roof deformation and surface subsidence under the three methods are conducted. The results show that the amount of roof and surface subsidence decreases successively by the caving method, the room and pillar method and the cement backfill method, and the maximum roof and surface subsidence by the caving method is 45.7 cm and 13.3 cm, respectively. Regarding shallow orebodies, the open-pit slope is obviously disturbed by the caving method and room and pillar method. Hence, slope displacement monitoring should be emphasized. Compared with the other two methods, the backfill mining method can use mineral waste as filling materials, but also it has less influence on roof and ground surface during excavations and is better at controlling the slope stability.