Development of an Efficient Process Scheme for Breaking High-Grade Iron Ores of Low Strength and Stability During Sublevel Caving

Abstract

Introduction. The main part of rich iron ores (73%) is mined in the Kryvyi Rih iron ore basin, most of which(160.5 million tons) are characterized by a low strength and stability.Problem Statement. One of the most important operations of slope excavation, which significantly affects the productivity of delivery vehicles and a crushing and processing complex, the quality and completeness of extraction of rich iron ores of a low strength and stability, is drilling and blasting operations to form a compensationspace with maximum, in terms of stability, dimensions and to hammer the main stock of the panel into it.Purpose. The purpose is to develop an efficient process scheme for breaking off reserves of rich iron ores of a lowstrength and stability, given the stress-strain state, efficient length of wells, and the quality of ore mass crushing.Material and Methods. The structural and functional analysis of the systems for the development of sublevel caving, the numerical calculations with the analysis and assessment of the parameters of outcrops of compensation chambers, the analysis and assessment of practical experience and scientific achievements in the field of increasing the efficiency of the ore breakage process, the analysis of techniques for the calculation of the parameters of drilling and blasting operations in the extraction of iron ores, the design of process schemes for breaking rich iron ores and their feasibility assessment.Results. For the first time, in this study, there has been developed a resource-saving version of the process schemefor the formation of a triangular-shaped compensation chamber and the hammering of the main stock of a breakage panel on it in the course of developing rich iron ore deposits of a low strength and stability, which allowspractically raising the efficiency by 7.8—18%, depending on the conditions of the breakage panel operation.Conclusions. The author has established the dependences of the angle of inclination of the inclined outcrop of thecompensation chamber and the line of least resistance. given the stress-strain state, the breakage energy intensity coefficient, the specific costs of breakage, and the efficiency on the distance of the breakage panel to the rocks of the hanging side across the strike of the ore deposit with one and two contacts of the breakage panel with collapsed host rocks.