JUSTIFICATION OF THE OPTIMAL HEIGHT OF THE EXTRACTION LAYER CONSIDERING THE QUALITATIVE AND QUANTITATIVE INDICATORS OF ORE RECOVERY FROM THE SUBSOIL

Abstract

Analysis of global experience in the application of underground mining systems for deposits of valuable and precious metals, characterized by relatively complex mining-geological and mining-technical conditions, shows that backfilling mining systems have become widely used. This is due to their exceptional structural simplicity and flexibility, the possibility of organizing underground ore sorting, a high degree of mechanization of stopping operations owing to favorable conditions for the use of self-propelled mining equipment, the ability to preserve the ground surface and surrounding rock mass from collapse, the simultaneous extraction of several ore bodies, and high qualitative and quantitative indicators of ore recovery from the subsoil.

Among backfilling mining systems, the underground mining system with descending layered stopping and cemented (hardening) backfill ensures relatively low ore losses and dilution. This is because the extraction of ore bodies in layers of small height makes it possible to mine ore bodies with extremely complex geometries. In this case, stopping excavations strictly follow the often highly variable contours of the ore bodies, resulting in nearly complete recovery of the mineral resource from the subsoil.However, in the case of ore bodies with an isometric morphological type (stock, stockwork), the application of the underground mining system with descending layered stopping and cemented backfill may result in lower qualitative and quantitative indicators of ore recovery from the subsoil. This is generally associated with the presence of indirect contact surfaces between the ore body and the surrounding host rocks.

It has been proven that the height of the extraction layer in the underground mining system with descending layered stopping and cemented backfill has a significant influence on the technical and economic performance of underground ore mining. It has been substantiated that an increase in layer height leads to higher levels of ore losses and dilution, which in turn results in a decrease in profit. The optimal value of the extraction layer height is 3 m, at which a rational balance between costs and ore recovery is achieved.