Reduction of ore dilution when mining low-thickness ore bodies by means of artificial maintenance of the mined-out area

Abstract

Purpose. The research purpose is to study the effectiveness of artificial maintenance of the mined-out space based on the use of cable bolts to reduce the dilution coefficient when mining low-thickness ore bodies. Methods. Geotechnical mapping of the rock mass according to the Q, RMR, RQD and GSI rating classifications is conducted, as well as a linear survey of the fracture system in the hanging wall and footwall rocks is performed using a rock compass and the GEO ID application. Numerical analysis by the limit equilibrium method in the Unwedge software package is applied to determine the safety factor of a mass divided by fractures into wedges. Using a Schmidt test hammer, the uniaxial compressive strength of the mass rocks has been determined. The full-scale studies have been conducted using cable support in the conditions of the Akbakai deposit. Findings. It has been revealed that the footwall rocks are in a stable state, while the safety factor of the hanging wall rocks is 0.98, which requires artificial maintenance using cable bolts. The cable support parameters are calculated taking into account nonuniform distribution of horizontal and vertical stresses in the rock mass. It has been determined that when strengthening the hanging wall with cable bolts in inclined veins with a dip angle of up to 40º, the average ore dilution is 66.1%, and that of previously mined without fastening is 68.7%. In similar experiments in steep-dipping veins with a dip angle of more than 60º, dilution decreases from 62.8 to 48.7%. Originality. It has been revealed that in the conditions of the Akbakai deposit, cable fastening of the hanging wall rocks is effective at an ore deposit dip angle of more than 60º, at which the mined ore dilution coefficient decreases. Practical implications. The research results can be used to increase the stability of hanging wall rocks when mining low-thickness ore bodies with a sublevel caving system.