Backfilling technology is not always used by mining enterprises, which is conditioned by technological and economic factors, such as the need for high mining rates and costs for the technological processes of transporting backfill materials from the daylight surface to the mined-out space. This concerns the underground mining of hard coal, which is a strategic energy resource, in the mines of Ukraine. This paper aims to study the effect of leaving the waste bottom rocks in the mined-out space of the longwall face without their drawing to the earth’s surface on the geomechanical state of the rocks surrounding the longwall face. The geomechanical assessment of the stress state of the rock mass surrounding the longwall face, when leaving the waste rocks from the seam bottom rocks in the mined-out space, is performed by the finite element method using the Ansys software package. A geomechanical model has been developed and substantiated, which adequately reflects the mining-geological conditions for seam mining within the extraction site, the actual structure and properties of the coal-bearing rock stratum, the parameters of the longwall face and the modified powered support for the processes of leaving the rocks in the mined-out space. The values and patterns have been determined of the decrease in the stress intensity concentrations in the coal-bearing roof mass in the frontal bearing pressure zone and destressing zone with an increase in the ratio of the rock pack thickness to the extracting seam thickness. The relative indicators of the load on the powered support section and the lowering of its roof have been determined by the ratio of the thickness of the rock pack formed in the mined-out space to the extracting seam thickness. The proposed mining method is of significant commercial and research interest for owners of coal mines developing thin coal seams because environmental costs for placing waste on the surface are reduced, and the energy potential of coal is increased due to the separation of waste rocks from coal in underground conditions. The need for a cycle of beneficiation of mined mass is eliminated and the geomechanical conditions of coal mining processes are improved.

In this article, variants of technological designing of new mining enterprise levels for obtaining the skills of engineering task execution are considered. The complex approach for the justification of a mine’s parameters is examined....

The purpose of this study was to develop a methodology for integrated monitoring of the rock mass state, which ensures the industrial and environmental safety of the Central Kazakhstan region. As a result of the research, a methodology for maintaining an integrated system of geodynamic monitoring has been developed. The results of predicting the physical–mechanical properties and stress–strain state of the rock mass are presented. Based on the data obtained, graphical–analytical dependences between the most important quantitative characteristics of the rock properties in the studied deposits are presented. The scientific novelty of the presented research lies in determining the pattern of changes in the structural peculiarities and strength properties of rocks with the depth of their occurrence, which makes it possible to predict the stress–strain state of the rock mass. The authors propose a new method for creating a geodynamic test site. The geodynamic test site created in the fields of Central Kazakhstan is a reliable basis for the organization of long-term monitoring for the earth’s surface deformation processes during large-scale development of the field, which improves the productivity and accuracy of observations. The results obtained can be used to improve the level of industrial safety at mines and minimize environmental risks caused by the subsoil development.

Opencast fields mining leads to land disturbance when conducting mining operations and storing of overburden rocks. The timely reclaiming of the disturbed lands according to the legislation requirements is an immediate duty of the subsoil user. The reclamation of the previously mined-out space of quarries refers to an extremely important tasks of the mining enterprise. The use of water management direction in reclamation assumes the use of previously mined-out space of a quarry to create the water reservoir through various methods of rehabilitation. There are presented various ways of designing the coastal zone of the created artificial water reservoirs in the previously mined-out space of the quarries located worldwide, which are used for the recreational purposes. The various profiles of slopes of artificial water reservoirs in a quarry with more low gradients, suitable for swimming and recreation are shown. Designing of a coastal area on the site of a quarry, intended for water reservoirs, depends on the water level position in the created body of water. The water reservoir, as the lake of artificial origin, created on the former quarry site, is shown. The purpose of the article is to substantiate the methodological approaches and engineering solutions concerning reclamation of the mined-out space after the opencast mining for the recreational purposes.

The coalification rank of the coal blend components and their caking properties initially impact the coke’s quality. In part, the quality of coke depends on the technological parameters of the coke production technology, such as the method of blend preparation, the coking condition, the design features of the coke ovens, and the technique used for post-oven treatment. Therefore, to improve the coke quality, the main attention is paid to the quality of the coal blend. The petrographic analysis is the simplest and most reliable way to control coal quality indicators under industrial conditions. In this paper, the effect of nine industrial blends on coke quality using petrographic analysis has been studied. Additionally, this paper addresses the efficient use of coals and the preparation of coal mixtures under industrial conditions, which contributes to the sustainability of cokemaking. For the preparation of blends, 17 coals were used, for which, in addition to petrographic and proximate analyzes, the maximum thickness of the plastic layer was determined. Industrially produced cokes were analyzed for coke reactivity index (CRI), coke strength after reaction with CO₂ (CSR), and Micum indices (M₂₅ and M₁₀). It has been established that the petrographic properties of coal blends are reliable parameters for assessing the quality of coke under conditions of an unstable raw material base, multi-component blends, and changes in coking regimes. Moreover, the research results have shown that to ensure the rational use of coals in the preparation of coal blends to achieve the required coke quality and consequently the sustainability of cokemaking, it is necessary to consider not only the mean reflectance of vitrinite but the proximate and caking properties of coals.