Improvement of sub-level caving mining methods during high-grade iron ore mining

Abstract

Purpose. To improve of the sub-level caving mining methods during mining of deposits of high-grade iron ores by applying a rational mode and intensifying the ore drawing. Methodology. It included an analysis of scientific literature, design documentation and the practice of mining of deposits of high-grade iron-ores in complex geomechanical conditions of deep horizons of mines, to establish the formation of fundamentally new foundations of scientific-and-design solutions for the rational extraction of minerals; numerical (application a special computer software package PFC 3D) and physical (based on the application of volumetric physical models and equivalent materials) modeling of ore drawing, aimed at identifying regularities of recovery process depending on the mining-geological and mining conditions of the mining of deposits, and also the physical- and-mechanical properties of the loosened ore mass. Findings. Regularities of changes in the qualitative and quantitative recovery percentages depending on the intensity of the ore drawing and physical-and-mechanical properties of the ore have been established using numerical and physical simulation. The obtained regularities made it possible to substantiate the rational parameters of the structural elements of the technological scheme for drawing and delivery of ore. A linear-alternating condition of ore drawing was developed, which will ensure an increase in the extraction of pure ore up to 10% and, as a result, up to 4.6% of quantitative and up to 5.2% of qualitative indicators of ore percentages, as well as up to 1.5% of absolute quality of mined ore mass. Originality. Power-law dependencies of the change in the angle of ore tapping on the intensity of the ore drawing and the ultimate strength of the ore for uniaxial compression have been established as well as dependencies of the increase in the volume of the tapping figure, when a linear-alternating condition of ore drawing is applied, on the intensity of the ore drawing, the height of the collapsed ore layer and the ultimate strength of the ore for uniaxial compression. Practical value. A linear-alternating condition of ore drawing has been developed, the implementation of which in practice makes it possible to increase the qualitative and quantitative recovery percentages and eliminate the human factor while observing the ore drawing planograms.