• Energy Research

The authors express their sincere gratitude to the management of the SE “VostGOK”, as well as to the employees of the Industrial Ventilation Laboratory at the State Research Institute for Labour Safety and Ecology in Ore Mining and Metallurgic Industry of Kryvyi Rih National University for their help and assistance in conducting this research.

Purpose. The present paper aims to enhance methodology for determining the safety and stability parameters of room mining systems with backfilling of the mined-out area when mining uranium ores in underground mines of the State Enterprise “Skhidnyi Mining and Beneficiation Plant” (SE “SkhidGZK”). Methods. The analytical research method used in the presented paper includes the analysis of previous relevant instructions and reports on the research performed at the SE “SkhidGZK”, as well as publications on the subject, operational geological survey documentation containing monitoring data on the stress-strain state of the rock mass surrounding the formed cavities and the actual state of the mined-out blocks in all underground mines of SE “SkhidGZK”. Findings. The research performed enables development of a new instruction for determining the safety and stability parameters of the room systems with backfilling when mining uranium ores in the SE “SkhidGZK” underground mines. Based on the developed new instruction, the stability of outcrops in mined-out rooms has been calculated, considering the actual time of their life. The obtained parameters fully correspond to actual stability of rooms in blocks of all underground mines. This indicates that the new instruction is more advanced as compared to the current Instruction and its implementation will contribute to mine safety enhancement. Originality. The increased depth of mining uranium ore in the SE “SkhidGZK” underground mines and the increase in lifetime of mined-out rooms require regular adjustment of the methodology for determining their safety and stability parameters. Based on the accumulated production experience, the observations conducted and a thorough analysis of the actual state of cavities, new and adjusted current dependences have been obtained that more accurately consider the impact of both determined factors and those unprovisioned in the current Instruction for determining the safety and stability parameters of rooms. Practical implications. The advanced methodology for determining the safety and stability parameters of room systems in comparison with the methodology described in the current Instruction at the “SkhidGZK” underground mines provides higher accuracy when determining the design parameters of rooms in the stoping blocks and greater reliability of predictive stability of both individual outcrops and rooms in general.

The article is aimed at determining regularities of muck drawing in blocks and developing the technology of enhancing of muck ore parameters through shaping a trapezoid block sill. To confirm the suggested assumptions, study regularities of forming and determine contours of crests after full muck drawing from the second stage blocks, laboratory experiments have been conducted on drawing muck ore on the boundary with solidifying backfill massif of I stage stopes. For the first time there have been determined numerical dependencies of ore losses in crests on the contact with the solidifying backfill massif of the I stage stopes after ore drawing from the II stage blocks on the dead stope height and dips of side surfaces of trapezoid basis of sill pillars when forming the trapezoid sill with inclined side surfaces of the lower part of the I stage stopes. There are developed methods of calculating ore losses in crests on the contact with the solidifying backfill massif of I stage stopes after muck drawing from the II stage blocks. There are proposed methods of determining optimal parameters of mining ore deposits considering minimization of re losses in crests and increase of muck extraction from II stage blocks.

Данные исследования выполнены благодаря исходной информации, представленной горнодобывающими предприятиями Криворожского железорудного бассейна, в частности “Евраз Сухая Балка” и “Центральный ГОК”.

The work considers conditions of deep levels of the Underground Mine Group for underground ore mining (as underground mines) of the Mining Department of the PJSC “ArcelorMittal Kryvyi Rih” (the PJSC “ArcelorMittal Kryvyi Rih”). The research aims to improve indicators of mined ore mass extraction when mining rich iron ores through studying and optimizing consumption of explosives, enhancing mining technology to provide fulfilment of the underground iron ore mining program. During the research, there are analyzed mining geological and technical conditions of the deposit mining as well as current technologies of iron ore mining at the Underground Mine Group of the PJSC “ArcelorMittal Kryvyi Rih”. The work analyzes the achieved indices and consumption of explosives for drilling and blasting at the Underground Mine Group. The mining geological and technical conditions of the deposit mining as well as current technologies of mining, parameters of preparatory operations, the nomenclature and qualitative characteristics of many types of explosives are determined to have changed. This complicates planning consumption of explosives and making their estimates for work sites. However, this is a reason for selecting highly efficient technology and machinery in deteriorating mining and geological conditions of operating at over 1200 m depths. The work determines dependencies of a stress value on a mining depth and physical properties of rocks, as well as parameters of drilling and blasting operations considering the stress-strain state of the massif under high rock pressure at deep levels of the Mining Group of the PJSC “ArcelorMittal Kryvyi Rih”.

The authors would like to express their sincere gratitude to the management of PJSC “Sukha Balka” for assistance in conducting the research and implementing its results.

Being one of the world’s largest uranium producers(about 2% of the world’s production), the state enterprise “Vostochnyi Mining and Processing Works” (“VostGOK”) provides about 40% of Ukraine’s nuclear power stations with uranium raw materials. Considering the conditions of uranium deposits exploitation (location in densely populated areas, protected sites etc.), to protect the environment from possible emissions of radioactive elements room mining is applied with subsequent backfilling of the dead area with consolidating mixtures. This technology is economically reasonable at deposits with the increased uranium content. To exclude a number of labour-consuming and environmentally dangerous operations from the production process, lean uranium-containing ores are reasonable to be mined applying underground block leaching. This enables reaching maximum values of mineral extraction and avoiding considerable material expenditures on backfilling mixture preparation and backfilling dead rooms, as they are almost completely backfilled with the muck pile, and on utilization of waste after the mined ore primary processing (barren rocks and off-balance ores) on the daylight surface.