Purpose. Substantiation of mining-technical and environmental safety of underground mining of complex-structure ore deposits based on the study of a rock mass stress-strain state (SSS), as well as determining the safe parameters of stopes for specific mining-geological conditions and patterns of rock pressure propagation in various environments. Methods. To assess the improvement of mining-technical and environmental safety of mining operations, the research includes theoretical generalizations with the use of mathematical statistics, physical and mathematical modeling, performing calculations, as well as technical and economic feasibility, laboratory and full-scale experimental studies, industrial tests in mine conditions and on the earth's surface in the zone of blasting influence, based on the standard and new methods. Findings. A functional interrelation between the rock mass SSS value and the number of impulses (destruction sounds) per minute, characterizing its structural (а) and strength (b) properties, is proposed, which is described by a curvilinear dependence of the type y = axb and allows to quickly determine the stable parameters of stopes. Assessment and prediction are made for various forms of rock pressure manifestation, based on the stress concentration coefficient within 0.91 Kv 0.70, taking into account the conditions of the elastic behavior of rocks. The value of = 0.0002-0.0003 is taken as permissible relative deformation, which ensures both mining-technical and environmental safety, as well as the rock mass stability during repeated blasting operations. Originality. A classification of the rock mass SSS has been developed depending on the direction of the maximum stresses relative to the mine working location, the level of the rock mass stress state and the mechanism of rock pressure manifestation (η), as well as the category of rock-bump hazard. In particular, the rock mass with the values in the range oof 0.12 < η ≤0.2; 0.2 < η ≤ 0.3; 0.3 < η ≤ 0.5 and η > 0.5 are classified as non-rock-bump hazardous and belong to III, II, and I hazard categories, respectively. Practical implications. To substantiate the safe parameters of stopes based on the results of multi-year research into underground mining of complex-structure deposits, depending on the rock mass properties, a graphical-analytic method (nomographic charts and calculation formulas) is recommended. These parameters are determined for highly fractured, medium fractured and weakly fractured rock mass with its horizontal outcropping to the surface. Using this method, the Instruction on the Geomechanical Substantiation of the Safe Mining of the Reserves at the Skhidnyi Hirnycho-Zbahachuvalnyi Kombinat, DP (SE VostGOK), Ukraine, has been developed.

One of the most problematic aspects of underground block leaching (UBL) of metals from ores is the possibility of pollution of water and air in the affected zone. Therefore, proving the possibility of mitigating environmental impact of metal leaching from ores by managing production processes with the implementation of nature- and resource-saving technologies is an important objective. The purpose of this study is to justify underground development effectiveness of ore deposits by traditional and integrated methods with leaching of metals from substandard and off-balance ores. This will allow the raw material base for extraction of metals from off-balance ores to be expanded and the environmental impact on subsoil and groundwater (hydrogeological systems) to be mitigated. A distinctive feature of a UBL (underground site for leaching of metals from shrunk ores) is that leaching solutions are supplied from sorption column placed in mining workings of the leaching level in the immediate vicinity of the extracting block. The pregnant solutions in the form of resin are discharged from the sorption column, placed in the leaching level mine workings, then winded in mine cars and further supplied to hydrometallurgical plant in tanks. A still rare attempt to justify the efficiency and environmental safety of underground metal leaching (UBL) from off-balance and substandard rock ores in installations mounted in mine workings, on the basis of monitoring and evaluation of subsoil and groundwater conditions was investigated. The average value of uranium concentration by level was established: 210 m – 3.6 mg/L; 225 m – 3.58 mg/L; 280 m – 0.91 mg/L. At the same time no contamination of underground mine waters was detected. Levels of sulfuric acid aerosols and radon decomposition products did not exceed the maximum allowable concentration (MAC) values. It is recommended that the hydrogeological environment be protected through silting the bottom of the stope for collection of pregnant solutions with clay mud and construct semi-active water-permeable chemically active barriers. The mentioned BIL process was implemented during the development of pilot block 5-86 and recommended for blocks 5-84-86 and 5-88-90 of Michurinskoye deposit of SE VostGOK, Ukraine, as well as during for development of ore deposits in Russia, Kazakhstan, and other developed mining countries.

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