The study aims to develop a method of effectiveness evaluation for geothermal heat recovery in closed mines of Donbas using relations of heat transfer theory in rocks and fluids. Geothermal heat is proposed to recover using coaxial geothermal probes to be installed in flooded closed mines. As a result of evaluation and ranking, five top promising sites with the highest expected performance indicators among 27 closed mines located in Donbas have been identified. The evaluation method takes into account geological settings, mine condition, and heat exchange parameters of the probe with mine water. The locations of the most promising sites were found to correlate with the areas of higher geothermal flux and the deeper mines. The results obtained can be used in feasibility studies on installation and operation of geothermal probes in closed mines.
Objective of the paper is to substantiate and implement the integrated approach aimed at the studies of filtration and mass-transfer processes within roof rocks of coal seams in the context of their underground gasification. Integrity of the studies is substantiated by the use of analytical calculations as well as physical and numerical modeling. Zones with different permeability have been determined and values of specific water inflow have been identified basing upon the performed numerical modeling and involving multicomponent transformations within roof formation. The research data actuality is in the studies of spatial and temporal dynamics of rock technogenic rock permeability above gasification channel depending upon their geological structure which will favour the substantiation of efficient engineering solutions to control a process of underground coal gasification under difficult hydrogeological conditions.
The provision of the energy system of Ukraine with a stable supply of coal in the long term demands calculation of the capacity of the exploitable deposits. Ukrainian deposits are characterized by insignificant thickness and complicated mining-geological conditions, which significantly complicates the mining process. Therefore, it is necessary to develop and use new energy-efficient technologies of coal mining. The article evaluates the criteria of usefulness of thin layers of deposits in the Western Donbass, which contains 25 bn t of coal, i.e 21.3% of total resources of the country, for processing in selective technology. According to the geologicstructural factor, we distinguished the fields of mines of hydrodynamically “open” and “close” types, the water inflows of which differ by a factor of ten. Taking the example of the mines of the east group, we ascertained the potential of the most promising coal reserves, which are appropriate for mining using selective technology. It was established that in these conditions, selective technology of coal excavation would not only allow a decrease in the ash content of the coal output, but would also prolong the period of the industries` operation. Backfilling of mined-out areas decreases the technogenic load on the underground and surface hydrosphere, decreases the subsidence of the surface and the volume of waste rocks.
The physicomathematical conjugation of filtration models of a flooded and an adjacent mine is carried out with a justification of methodological principles of analysis and prediction of a technogenic mode of groundwater in conditions of operation and flooding of a mine field. The identity of models and real objects is established as a result of solving a series of inverse problems and is confirmed by a water balance discrepancy of 0.003%, the convergence of water inflows in separate layers with a deviation of 5 – 12.5% and the coincidence of groundwater surface levels on models and data of a mode network. According to results of predictive solutions, it is established that dynamics of flooding of a rock massif within old stopes are more intensive than the restoration of a level of groundwater in a mine shaft. The options of technical solutions for curtailment of mining operations are justified, the ecological risks and costs of which can be optimized by constructing a water intake of technical (or drinking) water in the productive stratum of riverbed sandstones, as well as equipment for geocirculation heat supply systems using the capacitive resource of a flooded mine field.
Purpose is to determine factors of effect of mechanical parameters and geometry of packs, constructed using the undercut rocks in the process of selective coal mining, on the state of geomechanical system within a mine workingstope junction during a computational experiment. Methods.The computational experiments involved finite-element method to simulate three-dimensional analytical area of the geomechanical system. Rock mass was represented by twelve rock layers and a coal seam. In the process of the computations, neighboring rock layers displace freely relative to each other. Stresses and deformations have been calculated within a full-size 300×160×50 m block involving undisturbed rock mass, a stope and two development workings. Mechanical characteristics of packs were simulated using additional analytical calculations.Findings. The calculations of a geomechanical system of a mine working-stope junction have helped determine typical areas of the disturbed rock mass identifying a propagation mechanism of the stope roof fall taking into consideration the effect of backfilling parameters. Analysis of stress-strain state (SSS) of the geomechanical system within the stope roof, using the selected cross-sections, made it possible to define conditions of interaction of the rock layers resulting in the roof lowering on the packs.Originality. The identified regularities of interaction between a stope roof and backfilling components determine optimum conditions to control a stope roof during selective coal mining. It has been substantiated scientifically that consideration of longitudinal horizontal stresses to identify optimum backfilling parameters makes it possible to define unambiguously both a type, and geometry of protection schemes for the mined-out area of a stope in terms of different strength parameters and geometrical parameters of the disturbed rock mass. Practical implications.The results have helped determine a mechanism of a stope advance velocity as well as a type and geometry of the packs being constructed. The abovementioned makes it possible to minimize expenditures for internal logistics; to cheapen prime cost of mining; and to improve safety of stope miners.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.