Control of blast parameters for high-quality breaking of thin slope ore bodies

Abstract

Purpose. The research is aimed at substantiation of the effective method for mining thin slope ore bodies occurring in soft unstable host rocks by optimizing the breaking process, while determining the patterns of blast energy impact on the disturbed mass by explosive charges with controllable density, taking into account the geomechanical rock mass state. Methods. The research uses a comprehensive approach, including analysis of literature sources, practical experience of mining the slope ore bodies in difficult mining-geological conditions, modeling of the energy characteristics of blasts and wave action on the mass using software, as well as conducting experimental-industrial tests in the Akbakai mine. Findings. An innovative method for effective and safe ore mining from thin slope ore deposits in masses with weakened host rocks has been substantiated and developed. It implies the use of a new construction and location in the blast-holes of a charge consisting of mixed low-density explosives with widely controllable characteristics and with which the blast-holes are charged in two layers with different densities of explosives and detonated at different delay intervals. The optimum delay intervals have been determined, which improve the conditions for controlling the blast energy by changing the direction of the blast action vector towards the newly outcropped surfaces formed in the rock mass after the blasting the first stage charges. The main factors influencing the ore delivery range when mining thin slope ore bodies with blast delivery system have been revealed and methods for increasing this process efficiency are proposed. Originality. New parameters of drilling and blasting operations have been determined for the conditions of mining thin slope ore bodies of the Akbakai deposit: a rational charge construction with controllable blast characteristics has been deve-loped; the optimum range of blast-hole charging density with mixed low-density explosives and delay intervals have been substantiated; a new exponential dependence of the ore delivery range on the specific blasting agent consumption and the angle of the ore body occurrence has been revealed. Practical implications. Practical significance is in increasing the efficiency of blast breaking of minerals, improving the quality of blast delivery of broken ore to loading sites while maintaining the host rock mass continuity and reducing the ore mass dilution, eliminating the formation of large-sized pieces that complicate the blast delivery of the broken ore.