The technology of forming a backfill mass with the specified geotechnical characteristics

Introduction. To reduce ore loss and impoverishment, high-value non-ferrous metal reserves are commonly developed by the mining methods with worked-out area backfilling. Regardless of the type and methods of backfill mass formation, worked-out area backfilling, being a way to control the rock state, is highly labor intensive and incurs additional costs, therefore increasing the cost of stoping. During field exploitation, mining and geological conditions tend to constantly deteriorate, and complex mining conditions form, which is accompanied by decreased content of the commercial component. The more complex the mining conditions are, the higher goaf maintenance costs is and the lower the mining intensity is. So, as mining develops, production cost constantly grows while the commercial component content decreases, which negatively affects total production performance indicators. Therefore, searching for ways to solve the problem of backfill cost reduction remains an urgent practical task of mining. It is possible to optimize backfill costs under changing and constantly deteriorating mining and geological conditions without reducing mining productivity by means of the underground geotechnology with artificial industrially-modified mass formation with the required geotechnical characteristics. The technology is presented in this work and is aimed at the effective development of the field reserves. Research objective is to develop and substantiate the parameters of underground geotechnology with worked-out area backfilling, which controls geotechnical characteristics of an artificial industrially-modified mass during the stoping. Methods of research. A room-and-pillar mining method was designed and its parameters were substantiated, taking into account natural mining and geological conditions and mining technical conditions formed in the course of stoping. The research was based on theoretical calculations and geomechanical modeling. Results. A variant of a room-and-pillar mining method has been developed with worked-out area backfilling with dry rock and further consolidation with a hardening mixture and compaction by breaking reserves in a compressive medium. The results obtained showed the mining method’s effectiveness. The study substantiates the rational values of the mining method structural element parameters. In particular, the size of the chamber wall is determined, located at an angle of 80°, with the reinforced layer up to 5 m thick and 1.5 MPa strong. Conclusions. A variant of the mining method can be used when mining inclined and steeply pitching ore bodies in difficult mining and geological conditions.