The purpose of research is to increase the ore mass extraction ratio when mining rich iron ores by changing the shape of the stope chamber, as well as to substantiate its stable parameters under the conditions of the rock pressure manifestation. Used in mines existing methodologies for determining the structural elements of mining system are based on calculated equivalent spans of outcropping the stope chambers, which have a rectangular or tent shape. For the first time using the ANSYS software package, it has been determined that the formation of a compensation chamber of quasi-parabolic shape can significantly reduce the stresses concentration around the stope block. Thus, the formation of a stope chamber of a quasi-parabolic shape makes it possible to reduce vertical stresses as compared to horizontal ones without increasing horizontal pressure. When mining the extraction block, it is proposed to form the stope chamber of a quasi-parabolic shape with geometric parameters that directly depend on the parameters of the deposit, the depth of mining, and the direction of main stresses action. Dependences have been determined of the stresses value on the depth of mining and the physical properties of rocks, as well as on the length along the strike of the ore deposit. Thus, depending on the mining depth and length along the strike, rock pressure on the stope chamber of a quasi-parabolic shape decreases under non-uniform loading. The formation of a stope chamber of a quasi-parabolic shape will increase by 1.2 – 1.5 times the volume of pure ore that is recovered from the block.
The article aims at determining possible annual production considering mining and technical capabilities of the underground mine. Deepening of mining operations at Kryvyi Rih iron ore basin reduces considerably annual production of the useful mineral which results in increased mining costs. To maintain annual production, it is reasonable to build the second stage of opening the depth of which depends on production volumes. When determining the optimal depth of the first stage opening, it is necessary to apply a complex research method including the graphoanalytical one for determining the underground mine’s annual production and the industrial one for adjusting the methods considering technical conditions of the enterprise. It has been determined that annual production is influenced not only by mining and geological but also by mining and technical conditions. It has been proved that annual production of an underground mine decreases in direct proportion to the increased depth of mining. The speed of skips in the shaft is greatly impacted by the length of the main opening and its operating life. With the increase of the shaft operating life the skip speed decreases from 12 to 6 – 8 m/s. When designing the flowchart of further opening of underlying levels, it is necessary to consider both mining capabilities and technical conditions of the shaft and headgear, mining depth and the main opening operating life as well as the strategy of the mining enterprise. Consideration of the above mentioned factors enables maintaining the required annual production when mining iron ores at great depths. Under conditions of Kryvyi Rih iron ore basin, it has been determined reasonable to apply the main vertical shaft flowchart when mining reserves to the depth of 1650 m.
Selective mining of complex structured ore bodies will enable increased iron content in the mined ore mass in underground mining at Kryvyi Rih iron ore basin applying the existing mining systems. The article determines the way the grade changes in a mine block of a complex structured ore body when applying bulk and selective mining as well as factors influencing indices of extracting ore mass from the block. The investigation results prove that it is reasonable to mine complex structured ore deposits with barren inclusions applying selective mining if the iron content in the block varies from 64 to 67% and horizontal thickness of the barren inclusion makes 4 – 12 m. At that, the thickness ratio should not exceed 0.3. Stoping methods should be applied to receive high indices of ore mass extraction. There is determined an ore/barren inclusion-to-ore body thickness ratio considering the dilution factor that confirms practicability of selective mining of complex structured ore bodies. Selective mining of complex structured ore deposits of Kryvyi Rih iron ore basin applying open stoping enables increasing the mined ore mass quality without considerable capital and operating costs and, consequently, staying on the market and enhancing the environmental situation in the region.
Purposeis development of the methods to predict indices of iron-ore deposits relying upon the improvement of available techniques as well as formulation of new geometrization procedures and identification of the most adequate decision-making way to assess geological data as the basis for geometrization and prediction. Methods are to develop a self-organizing prediction algorithm based upon combination of the available techniques and formulation of new mathematical methods; consider various means to assess them in the context of iron-ore deposit; and select the most efficient one. Use of geostatistical methods makes it possible to evaluate and process output geological information. The methods help assess mineral reserves of a mining enterprise. Findings. Dependencies of magnetite ore content upon geological factors have been derived in the context of an open pit of PIVDGZK JSC. The deposit has been geometrized; predictive mining and geometric model of the deposit site has been deve-loped. Factors have been determined influencing the distribution nature of the indices. Graphs to arrange grade indices of the deposit have been constructed. The graphs have helped predict their placement within the deposit. Originality. A method to predict mining and geological indices of iron-ore deposit has been developed relaying upon a self-organizing algorithm. Correlation between grade indices of minerals and different geological factors has been determined making it possible to describe spatial distribution of grade indices of the deposit. Practical implications. Geometrization methods for iron-ore deposits have been formulated. The methods help schedule mining operations accurately while improving their efficiency. The developed predictive self-organizing algorithm is the flexible tool used for various mining and geological conditions to provide scheduling and assessing of different mining methods. The self-organizing as well as geostatic evaluation techniques is quite a promising research tendency.
The aim of this study is to analyze the existing methods to determine the presence of harmful substances in the open pit atmosphere after massive explosions, and to develop a method of measuring the gas composition of the atmosphere using unmanned aerial vehicle (UAV). Existing methods of controlling the whole open pit atmosphere and its individual sections do not meet safety requirements. The main disadvantages are that workers should be present at danger zone and they are exposed at risk of poisoning by harmful gases. In addition, these methods require considerable time for delivery and analysis of samples in the laboratory, and the results contain significant measurement errors. Therefore, it is necessary to develop a methodology to determine the presence of harmful substances in the open pit atmosphere after massive explosions using UAV device, and conduct analytical research of signal dissemination to UAV control in the air. It was established that the implementation of the proposed method will allow to get quickly reliable data on the chemical composition of atmosphere in the explosion areas. It is possible to carry out the control measurements during mining operations without their interruption and without people presence in the dangerous area which allows to increase safety.
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