Abstract
Purpose. Determination of the granulometric characteristics and loosening coefficient of mine rocks formed during stope operations from undercutting the bottom rocks as a potential backfill material based on a set of mine and laboratory research. Methods. To do research, a complex methodology is used, which includes a photographic surveying the mass of destroyed rocks from undercutting the bottom rocks in mine conditions, digital processing and determining the granulometric composition in the software package, sampling the mine rocks at the surface complex, and reconstructing the granulometric composition, similar to the full-scale mine conditions in the laboratory. Sieve analysis, laboratory balance and laboratory container are used to determine the granulometric composition and loosening coefficient. Findings. The dependence between the granulometric composition and loosening coefficient of rocks, which increases by 33% within fractions of 0-50 mm and by 8% within fractions of 50-140 mm, has been revealed. It has been determined that the destroyed rocks in the face within fractions of 0-140 mm have a bulk density of 1.28 g/cm3, loosening coefficient of 1.7, the voidness of and the maximum reserve for the backfill mass compaction with mine rocks is 41.9%. An analytical assessment of the volumes of the formed cavities of the mined-out area in the longwall face and gobed mine workings, as well as the prospects and completeness of their filling with mine rocks have been performed. Originality. It has been determined that the loosening coefficient of mine rocks destroyed in the stope face by KA-200 shearer changes according to the logarithmic dependence on their granulometric composition. This makes it possible to control the granulometric characteristics of the backfill material to achieve the maximum density of the backfill mass. Practical implications. Further research can serve as a basis for determining the rational parameters for the formation and placement of backfill masses during complex-mechanized selective mining of coal seams using various methods of backfilling operations.
Highlights
In developed countries, the rational use of natural resources is an important component during mining of various types of minerals, since environmental protection is the most important principle of modern society
It has been determined that the destroyed rocks in the face within fractions of 0-140 mm have a bulk density of 1.28 g/cm3, loosening coefficient of 1.7, the voidness of and the maximum reserve for the backfill mass compaction with mine rocks is 41.9%
It has been determined that the loosening coefficient of mine rocks destroyed in the stope face by KA-200 shearer changes according to the logarithmic dependence on their granulometric composition
Summary
The rational use of natural resources is an important component during mining of various types of minerals, since environmental protection is the most important principle of modern society. Particular attention is paid to the coal mining industry, since the implementation of a number of technological mining processes has a negative impact on the natural environment for a number of factors. The latter include subsidence of the daylight surface in the absence of backfilling the mined-out area [1]-[3], accumulation of waste rock dumps and tailings over large areas, as well as atmosphere pollution with coalmine methane and products of blasting operations, pollution of surface water bodies with highly mineralized mine waters [4]-[6].
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