Quang Ninh coalfield over the years has witnessed geotechnical issues such as surface subsidence and strata caving, deformation and fracture due to the underground coal mining.
These issues have been preliminarily investigated mostly by using field observation.
The corresponding solutions and measures, however, seem to be inactive and perfunctory. This paper presents an analysis of height of strata caving, evolvement of deformation and movement zone, caving angle in strike direction, surface subsidence and strata movement when mining thick-gently inclined and/or closely distributed coal seams by using a physical model based on a case study of Khe Cham basin, Quang Ninh coalfield, Vietnam. The model shows that roof strata cave cyclically with a height being 5-6 times mining height; caving angle ranges from 64 to 67 degrees; maximum subsidence magnitude stabilises around 1.5 m; and strata behaviour caused by the mining of lower seam is less severe as that of the upper seam. The paper’s findings are useful for engineers to better plan and design technical solutions to improving safety in thick coal seam extraction.
One of the common ways to deal with unproductive losses of raw materials and atmospheric pollution from technological baths of electrolysis production is aspiration. Ensuring sanitary conditions in the workplace due to only aspiration is difficult due to a sharp increase in the volume of exchange ventilation. The use of airborne suction is accompanied by the entrainment of the electrolyte in the form of a droplet liquid and steam. Heat losses during electrolytic refining of copper in the traditional version reach 70 - 80%. In order to reduce the release of carcinogenic aerosols into the atmosphere, a foam protective layer is created on the surface of the electrolyte. The disadvantage of this method is the low efficiency of protection, the instability of the foam layer, its explosiveness and toxicity of some blowing agents. Placing floats on the bathtub mirror also allows you to close the bathtub mirror. The company refused to use this method due to the inconvenience of servicing electrolysis baths. When caring for the hardening concrete mixture, it is necessary to ensure optimal thermal and humidity conditions, on the observance of which the normal increase in the strength of the material depends. To create a warm environment and to intensify hardening of concrete, work is carried out in light temporary buildings-heaters or under film coatings. In the latter case, the concrete is covered with a vaporwaterproof film and kept in such a closed volume until the design or critical, relative to moisture loss, strength is set. The calculated dependences of determining the thickness of the film coating, tensile strength and elongation at break are presented. Physical-mechanical and electrical characteristics of a plastic film are presented. A description of the design features and operation of the new drive shelter device is given.
Due to growth of interest in tourism, in recent years in the Altay territory several zones of the increased concentration of tourist objects are formed caused by river basins and orographical barriers. The territorial tourist and recreational cluster − group of geographically adjoining interacting companies, public organizations and the related state bodies forming and serving tourist streams and territories using recreational potential. Feature of emergence of such cluster is need of creation of technological communications between the enterprises and sectors of economy participating both in production, and in realization of tourist's products. According to the orogidrografichesky system of a northern macroslope of the Altai highland it is possible to speak about the system of basin tourist clusters. Each of them has unique features with existence of the dominating objects which at the organization of binding routes allow to provide in the long term sustainable development of branch of tourism, a recreation and treatment. The documents of territorial planning developed in recent years poorly are used in expeditious practice. The expediency of their updating and careful study taking into account quickly changing picture of land use, emergence of the new especially protected territories, environments of the domestic and international market of tourist services is undoubted.
The research object. The proposed article considers the climatic features, the state of the ice and snow cover of the mountainous Pamir as a source of food for numerous rivers and the climate-forming link in the region of Central Asia. Goal. To analyze the processes in the Pamir’s mountain ecosystem regarding snow-ice and water aspects in the spectrum of changes occurring on a planetary scale. To establish the influence of mountain orography on the distribution of air masses and the formation of snow cover, the change in the river hydrograph due to changes in the current state of the climatic factors of the mountain river basin. Methodology. The analysis of the snow-ice resources state of the Pamir was carried out based on extensive use of archival and modern data using statistical classification to establish the dynamics of their changes in climate warming conditions. A comparative assessment of changes in the hydrology of the Pamir rivers was carried out by comparing modern hydrological characteristics with the early period. Results. Analysis of the glaciers and snow cover state in the mountains of several countries showed that climate change makes significant adjustments in the functioning of many components of the ecosystem, and especially in reducing the area of glaciation and glacier degradation. The studies results of the climate change impact on the snow-ice resources of the mountainous Pamir using the example of the upper reaches of the Trans boundary Pyanj River show a significant impact of mountain orography on precipitation and the formation of snow cover. Conclusion. A deep analysis of the published works on the effects of global climate change on the snow-ice resources of high mountains demonstrated that the mountain ecosystem is particularly sensitive to climate cataclysms. The heterogeneity of the spatial distribution of precipitation and the depth of snow cover in the Pamir in three climatic zones upstream of the Pyanj River is noted. The western climatic zone of the Pamir is characterized by more abundant precipitation than the eastern zone. It is assumed that the decreasing trend of precipitation is due to the fact that the eastern part is subject to the inflow of dry mass. The mass of the air of the Indian Monsoon is unloaded when passing high mountain ranges and only dry residue enters the eastern part of the upper reaches of the Pyanj River. The impact of climate change on water flow is analyzed using the example of the water content of the Vanch – tributary of the Pyanj River, and a comparison of the water volume values of the Vanch River in two periods (1940–1970 and 1986–2016) revealed its increase over the period 1986–2016.
Spatial variation of tectonic activity along Golpayegan drainage basin in Iran are assessed using morphometric approaches by taking advantages of Geographical Information System, GIS. The Golpayegan region is located in the central part of SanandajSirjan metamorphic zone, SSMZ, of Iran, where is affected by Iranian – Arabian continental plate collision. The quantitative study of morphometric indices allows to compare geomorphic features and to zoning out and interpret the intensity of active tectonics. In this research, some morphometric indices such as Sinuosity of Mountain Fronts (Smf), Faceting of mountain fronts (Facet), Valley floor index (Vf) and valley ratio index (V ratio) is surveyed to be able to zone out the tectonic activity level in the water basin of Golpayegan taking advantages of fuzzy AHP method in the GIS environment.
When replacing expensive and scarce cement for the preparation of concrete mixtures, one of the promising alternative binders is fly ash which is formed when coal is burned at thermal power plants. The feasibility of such a replacement depends on the results of studies of the effect of the number of additives of complex binders of different types to cement on the strength of concrete mixtures. The aim of the research was to determine the dependence of concrete strength on cement consumption with fly ash additives, which allows to evaluate the effect of reducing cement consumption while maintaining the quality of concrete. As part of the research, the efficiency of the mixing operation of concrete mixtures components, which significantly affects the physical and mechanical properties of concrete products, was evaluated. So, it is determined that when the intense components mixing of concrete mix in the disintegrator concrete strength increases 1,5-2 and more times. It is established that the optimal mode for mixing the concrete mixture in the disintegrator is the relative velocity of particle collision of 30 - 40 m/s, and a further increase in this velocity is impractical. The results of determining the quantitative parameters of the dependence between the flow rate of cement with fly ash additives and the strength of the concrete mixture are the basis for optimizing the ratio of binder and inert components with a decrease in cement consumption while maintaining the desired quality of concrete. The quantitative values of optimal speeds of mixing are obtained experimentally by comparing alternatives by mixing manually or in the disintegrator. Partial replacement of cement with alternative substances is a promising direction to reduce the deficit of binders not only to ensure the volume of preparation of concrete, but also to reduce the load on the environment. With the intense components mixing in the disintegrator concrete strength increases 1,5-2 and more times. The results of the study are of interest in the manufacture of concrete to fill technological voids formed by the excavation of minerals in the process of underground mining. The proposed technology is a reserve for obtaining economic effect in the modernization of mining and related industries.
Traditional technologies for the development of ore deposits of the Dzhezkazgan deposit, including a standard set of geological and technical measures were able to stop the downward trend in the study of the characteristics of the mineral substance of useful components to a certain extent. But this effect can not last long. There is a need for a comprehensive analysis of the quality, relationship of composition, structure, physical properties and genetic characteristics of the mineral substance with the technological properties of minerals on the example of Dzhezkazgan deposit. The decision on introduction of new technologies is made on the basis of their detailed assessment on a set of technological, economic, technogenic and other factors important for mining and processing industry of the mountain region, its population and natural complex as a whole. Purpose of research. Study of interrelation of composition, structure, physical properties and genetic features of mineral substance with technological properties of useful components of Dzhezkazgan deposit. Research result. The results of the study make it possible to effectively make organizational and technological decisions for the correct choice of new technologies of the mining and processing complex. The peculiarity of the study is that the proposed method can be used in the fields of the mountainous regions of the North Caucasus. Summary. 1. Study of mineralogical characteristics of rocks containing three packs: quartz-carbonate rocks (PCM), quartz-siderite rocks, which are marking for the ore-bearing horizon (PS), mineralized rocks of near-contact ore zones (MZ). In laboratory studies, monofractions of bornite, chalcosine and Galena were isolated along the three lower horizons, and the chemical composition of impurity elements were determined by spectral analysis. 2. It is established that impurities in bornite, chalcosine Galena, such as Ag, Be, Bi, Cd, Co, Fe, Mn, Ti, Zr, gradually increase, and such as As, Ni, V, W, decrease, the content of the remaining elements is less than the sensitivity of the device. Various technological types and grades of ores are defined, the assessment of technological properties of raw materials that allows to define an effective way of processing of ores and indicators of extraction is carried out.
Currently, the most impactful method of reservoir development for efficient oil recovery is water flooding. The main objectives of this method are to maintain reservoir pressure and increase the final oil recovery rate. However, formation damage caused by suspended particles in injected water always occurs during water flooding, thus leading to injectivity decline. This also gives rise to higher injection pressures, above the maximum injection pressure than the surface facilities can provide. Relatively little consideration is given to formation damage in the process of well control optimization. In this study the effect of formation damage caused by clay particles dislodged by low salinity injection water on the well production performance is predicted by coupling an analytical model with a reservoir numerical simulator. This method is applied in a Niger Delta type field model to evaluate its effectiveness. The strength of the model lies in its ability to predict accurately effluent concentration profiles, permeability changes during reservoir water flooding, and the evolution of the filter coefficient with time using bed filtration model. In this study, model predictions for different particle and pore size distributions of particles are in agreement with experimental data.
Underground mining of ore deposits, sub-floor caving systems with end ore output are widely used but losses and dilution limit their application area. In the underground mines of Russia, they are the main ones in the extraction of iron and phosphate ores, for example, in the Krivorozhsky basin, Mountain Shoria, mines of the Nizhne-Tagilsky plant, and at a number of large non-ferrous metallurgy enterprises. Systems with massive collapse are used in deposits of powerful and medium power. The treatment space is not supported (with the exception of the formation of chambers or slots to collapse the rest of the block in some systems), the breakdown is predominantly borehole, sometimes using controlled self-collapse. The goal of improving the parameters of caving development systems is to develop recommendations for reducing economic damage from lowering ore quality. The chess layout of the treatment faces of the diamond-shaped form is considered. The proposed technique uses the condition of inscribing the release figure into the contours of the beaten and produced ore layer. The maximum allowable for economic reasons ore dilution is determined taking into account technical, technological and technical and economic factors. The stages of mining the ore section are ranked as: drilled section; broken ore layer before release; release figure corresponding to the output of pure ore; a release figure corresponding to the interim release and a release figure corresponding to the final release. The results of calculating the release indicators for the moments of release are the basis for managing the quality of the ore extracted during the release process. Extraction rates taking into account dilution by rocks may be proposed to be determined graphically. Correct methods for calculating ore dilution, production rate and losses are proposed. Ore caving technologies have priority in the extraction of metal ores. Reducing losses and dilution is a reserve for increasing the efficiency of this high-performance technology. The proposed methodology for calculating the extraction indicators improves the accuracy of designing the parameters of the development system, which optimizes them taking into account the nature of the contact of ore with the host rocks, thereby allowing the use of this technology. The new methodology for calculating the parameters of the sub-floor caving system and the analytical, empirical and graphical possibilities of its implementation are applicable in the design and operation of mining and processing enterprises. The proposed technology is a reserve for obtaining an economic effect during the modernization of mining and related industries.
On the example of one of the large enterprises at the foothill zone of the North Caucasus – LLC Kavdolomit, which provides leading enterprises of the Russian Federation and neighboring countries with dolomite, the need for replacing the dry method for collecting small particles of dolomite flour, including nanoparticles, in bag filters that are unable to capture particles by size it is shown less than 1 micron due to the structure of the fabric on a promising wet method of dust collection. At NCIMM (STU) on the basis of the patented design of the distribution plate, a jet bubbler design has been developed in which a foam regime effective for trapping small particles is created due to the impact of gas-liquid jets without the use of surface-active substances. It is known that the mechanism of bubble formation in the bubblers is determined by a large number of parameters and is extremely complicated; therefore, the development of a mathematical model of the air bubbles formation is important for the theoretical assessment and prediction of the results of the bubbling process initial stage and for obtaining data for the design of the industrial jet bubblers. The process of bubble formation from the vertical slots of the bubbler caps is considered in stages. 1st stage – opening the windows of the slots of the cap. The formula for determining the static pressure requires to open the windows of the slots and the initial opening of the slots. 2nd stage – the formation of air bubbles. The process of separation of the bubble from the window of the cap slot is considered, provided that the forces acting on the bubble at the time of separation are equal. As a result, the formula is obtained for determining the rate of air outflow from the slot needed to detach a bubble. Based on the obtained mathematical model, a methodology has been developed for calculating the parameters of the air bubbles formation process in the jet bubbler: the initial opening of the slots, the static pressure under the cap of the cap and the rate of air flow from the slot. A comparison of the calculated value of the velocity of air outflow from the slots of the cap with the literature data for the velocity values in the holes of the bubblers indicates the adequacy of the obtained mathematical model.
ISSN 1998-4502 (Print) ISSN 2499-975Х (Online)