Deterioration of geological and mining conditions for underground extraction of coal deposits with increasing depth leads to significant gas release into mine workings, reaching 45 m³ or more per 1 ton of coal mined at some mines. Existing standard methods for degassing of stressed coal seams often do not provide required degassing efficiency of 50 % and more for rhythmic operation of production faces. In some conditions, open-hole degassing efficiency of 30 % can be achieved, which allows to increase output per face up to 1,000 tpd with gas release from seam up to 5 m³/min. However, at depths of 1,000-1,300 m and high-performance operation of longwall sets of equipment, gas release can reach 170 m³/min that causes face stoppages due to gas hazard and slows down the pace of stope development and stoping. In addition, preliminary seam degassing requires rather long time. Modem achievements in the field of rock hydraulic fracturing are the basis for the development of low-energy safe and environmentally friendly technologies for degassing of stressed gas-saturated coal seams. The paper presents the findings of our studies on hydrodynamic action (HDA) on a gas-saturated flat-lying coal seam and the developed method for degassing and reduction of gas-dynamic activity of stressed coal seams in mine workings. Chemical interaction of some coal free radicals with water molecules and hydrolysis products has been revealed, resulting in formation of stable compounds. This leads to decreasing concentration of coal paramagnetic centers (PMC) and sorption activity. Our mine tests have for the first time found hydrodynamic effects on geotechnical and gas-dynamic processes in a coal mass during formation of a zone of intense gas release. Technology and layout for hydrodynamic action-based degassing of gas-saturated flat-lying coal seams have been developed, providing for spatial and time separation of seam degassing and coal extraction processes.

Currently, an adverse environmental factor in the Soligorsk mining district is the effect of underground mining on the terrain and landscape. The remarkable thing is that flooding and waterlogging in the undermined territory of the potash mine fields is connected with specific natural conditions of the district. Clay-salt tailings are known to be stored in salt tailings piles. To prevent the filtration of brines and diffusive penetration of salts into underlying soil and groundwater and thereby prevent salinization of geological environment, in the areas where salt tailings piles are located and on the slopes of bund walls, an impervious screen is arranged. It was noted that in recent years, Belaruskali OJSC’s ore departments have been widely using high-altitude solid waste piling method, which reduces the area occupied by salt tailings piles. To prevent and eliminate excess brines, Belaruskali introduced a method for biological reclamation of spent salt tailings piles, which provides for creation of vegetation on the soil layer surface and the conditions for its self-regeneration. Five degrees of groundwater pollution in the Soligorsk industrial district were distinguished: low, medium, periodically high, high, and catastrophically high. It was found that the following factors have negative impact on flora and fauna in the district where potash enterprises operate: land acquisition for industrial sites, salt tailings piles and TSF and, as a result, reduction in the area of vegetation cover; flooding and waterlogging of lands due to subsidence of the earth's surface above the worked-out mine workings; salinization of territories adjacent to the enterprise by excess brines; impact of industrial dust and gas emission. One of salinization control measures is creation of forest shelter belts.

Surface water pollution is one of the consequences of modern society development through permanent pressures on the environment imposed by economic activities to provide the necessary resources for keeping modern living standards. Degradation of fresh water bodies is caused by the disappearance of natural water collection areas, deforestation and unsustainable farming practices, river pollution with wastes and the discharge of non-treated domestic and industrial wastewater into natural recipients. The main purpose of the mathematical modeling of rivers is to predict pollution dispersal in longitudinal and transversal directions, taking into account water body mixing coefficient. This paper is devoted to monitoring of physico-chemical indicators in the sampled river reaches and simulation of pollutant dispersal in the upper reaches of the East Jiu river.

The paper is devoted to studying issues of machinery thermal state monitoring using generalized approach to objectives of electromechanical system (EMS) diagnostics based on current temperature values. Generalized mathematical model of EMS (a homogeneous body or a multi-weight estimated heat balance diagram) for various operation conditions of a facility allows to identify diagnostic indicators (criteria) for taking specific measures to stabilize its operation. Increasing efficiency of the facility thermal state monitoring can be achieved using noncontact measuring instruments to determine temperature distribution over the facility surface. Temperature distribution over an EMS facility surface enables concluding on maintenance necessity. For effective application of noncontact thermal-imaging equipment for diagnostics of EMS on the basis of the provisions presented in the paper, training program for specialists in thermometering of industrial facilities has been developed.

The features of originating load on “support-interframe shield” system in the process of formation of broken rock zone around a mine working were investigated by laboratory tests on models of equivalent materials and structural models. The role of interframe shield in the formation of frame support load has been revealed. It was found that a natural self-supporting arch is formed over interframe shields within the broken rock zone, which redistributes the load on the roof support frames, while the weight of rocks within the arch puts pressure on the interframe shields. The requirements for interframe shield of frame supports in mine workings have been developed.

Backfilling optimization is carried out through the use of discrete rock properties. A new line of the process improvement is based on the phenomenon of performance of residual rock strength when jamming in the process of underground mining of deposits within faulted rocks. The research is aimed at reducing costs of backfilling while ensuring the work safety. The goal is achieved by comparing backfilling options depending on the formation of rock natural self-supporting arch. The study is based on the provisions of structural mechanics and continuum mechanics using the phenomenon of performance of residual rock strength due to rock jamming. The backfilling concept has been formulated. Information on geological structure of the studied rocky ore deposit of complicated tectonic structure and the roles of tectonic framework in the behavior of the ore-hosting rock mass in the course of opening by mine workings are presented. The findings of the study of the rock mass condition with determination of characteristic geotechnical domains are presented. Variants of the ore-hosting rock mass behavior are considered depending on natural jamming of elementary structural rock blocks within the arch. The possibility of combining sealing and setting-mix backfilling methods has been clarified. The area of the research findings application in mineral underground mining is recommended. The determination of dangerous displacement area boundaries in rock mass using the mechanism of discrete rock jamming allows achieving higher mining effectiveness while ensuring mining safety. The study results can be used in underground mining of minerals.

Reservoir simulation is a powerful tool to mimic the formation behaviour during primary production and later on for planning enhanced oil recovery (EOR) pattern. However, all available commercial and developed scien-tific/academic software for this purpose is based on either finite difference method (FDM) or finite volume method (FVM). Recently finite element method started to gain more attention in the scientific and commercial practices due to its robust results and the ability to deal with complex boundaries. COMSOL Multiphysics is a finite element method (FEM)-based software, having very special features, which are different from standard reservoir engineering software packages like Eclipse or CMG, which are black box-type software. The most important feature of the COMSOL is that user can see equation and modify it - customize for specific conditions and objectives, as well as couple different physics together and apply different solvers, which are under user’s disposal. In this paper, short background of FEM will be illustrated and then the mathematical models of two-phase immiscible flow of water and heavy oil will be reviewed and simulated using COMSOL Multiphysics on the famous inverted five-spot model. The comparison between the results of Comsol Multiphysics and Eclipse shows good agreement. This study is the first step in applying Comsol Multiphysics to reservoir simulation. Further steps will involve simulating thermal enhanced oil recovery using steam flooding technique and coupling Comsol Multiphysics with CMG software package to enhance simulation inputs and outputs.