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Analysis of conjugate heat and mass transfer during aerosol flotation of gold from placers

Sergey I. Evdokimov, Tatiana Е. Gerasimenko, Ruslan N. Maksimov, Yuri G. Klykov

Introduction. The probability of replenishing the SME of placer gold by registering the reserves of new deposits is low, and the involvement of man-made waste in the economic circulation will allow maintaining the achieved level of gold production from placers for 10-15 years. Purpose of research. The aim of the study is to develop a technology for extracting gold from old wastes of alluvial mining based on the identified patterns of conjugate heat and mass transfer during aerosol flotation of metallic gold. Methodology. For the development of technogenic wastes of alluvial gold mining, an enrichment module based on gravity and flotation methods has been developed. The module equipment has passed research tests in industrial conditions. During flotation, the increase in the gold content in the operation of the main flotation is carried out by mixing the crude concentrate isolated from ½ of the original feed with the other ½ of it. A mixture of air and hot steam was used as the gas phase during flotation. Research results and discussion. The temperature difference at the gas-liquid interface is the driving force of the vapor-liquid phase transition with the release of significant condensation heat. The time of particle sticking to the bubble is commensurate with the time of heating the interfacial surface due to the heat of vapor condensation. This allows us to consider temperature as one of the reasons for changing the result of flotation by a mixture of air and water vapor. Due to vapor condensation, the bubble size and the intensity of interfacial heat transfer decrease. When the minimum size is reached, overheating of the vapor in the bubble leads to an increase in the evaporation of the solvent and pressure in the gas phase: the heat transfer between the phases and the size of the bubble begin to increase. Transient processes in steam are non-polytropic and the limiting bubble sizes decrease with time: at the minimum size and maximum temperature, the heat transfer of steam is higher than the heat transfer of water with an increase in the size of the bubble and a drop in temperature in it. The limiting transitions of the bubble size are the cause of high-speed oscillations of the bubble walls, which decay with time. When the bubble surface is stretched in the three-phase contact zone, the gas-liquid surface tension increases due to a decrease in the density of the adsorption layer of surfactant molecules, which causes an increase in the force holding the hydrophobic extractable particle on the bubble surface. Radial tensile-compression deformations lead to shedding from the bubble surface of hydrophilic gangue minerals randomly retained by the bubble surface (for example, in the case of high occupation of the bubble surface by extracted particles). Conclusion. It is substantiated that the combined gravity-flotation technology is economically justified: the added value of marketable products provides an increase in the value of the net present value and the return on investment index, and a reduction in their payback period. It has been proven that the addition of gravity technology with flotation methods for extracting gold provides an increase in annual metal production by ~27% rel. due to the additional extraction of forms of gold that are “resistant” to gravitational methods.

Number of views: 356

Natural parks, balneological resources аnd rural development

Irina P. Glazyrina, Nadezhda V. Pomazkova, Oksana Ts. Darmaeva

Introduction. One of the priority directions in the field of environmental protection is the construction of models for the development of the territory designed to combine the interests of nature conservation and sustainable development of territories, including the development of environmentally friendly industries and the dissemination of experience in sustainable environmental management practices. The availability of balneological resources enhances the attractiveness of the territories and can be an additional source of income for the local population. One of the ways to solve these problems is to include them in specially protected natural areas, and this strategy often brings good results and contributes to the "green" growth of the local economy. This is evidenced by numerous examples in Western Europe and North America and, to some extent, this is also the case in Russia. However, experience shows that this does not always meet expectations, and it is not enough to give the territory the status of a park. The purpose of the research. Using the example of the Arey Park in the Trans-Baikal Territory, to identify the reasons for the failures of attempts to use the European experience of natural parks in the eastern regions of Russia as factors for the development of a "green" economy in rural areas. We are considering the experience of creating a nature park in 2013 in order to protect the ecosystem and use the valuable balneological resources of Lake Ares in accordance with the goals of the "green" economy. Research results. The paper shows that, despite some improvements in the state of the coastal ecosystem, the status of specially protected natural areas (protected areas) does not contribute to achieving the originally set goals. Its balneological resources, including therapeutic mud, are used uncontrollably in the shadow sector, which does not guarantee either effective treatment or environmentally safe withdrawal. Similar problems arise for other forms of recreational services when organizing campsites, arranging hotels and food outlets. Therefore, the park practically does not realize its potential either as a driver of the growth of the local economy or for the effective use of balneological. The authors analyze the causes of the processes taking place and also propose a number of measures to involve the natural resources of parks in the local economy in such a way that their use brings economic benefits to the local population, while maintaining high environmental quality.

Number of views: 365

On the determination of buildings technological deformations in geotechnical construction

Elena Yu. Kulikova, Dmitry S. Konyukhov

Objective. The purpose of this work was to determine technological deformations and identify their causes during mining and construction work. Introduction. The modern world is characterized by the expansion of the scale of underground construction, which has a large arsenal of advanced technologies, tunneling equipment, etc. In urban conditions, underground construction is carried-out in the zone of influence of existing land development. At the same time, due attention is not paid to the technological deformations of the existing development. Methodology. Analysis of the results of experimental and practical geotechnical monitoring shows that any technologies of underground construction in conditions of dense urban development cause “technological deformations” of existing buildings, significantly (40-90%) affecting the safety of buildings in the process of new construction. They depend on the mining and hydrogeological conditions of the construction site, the quality of work, the type of enclosing structures of the pit and equipment used. Concomitant reasons are parameters such as the length of the gripper during construction by the trench “wall in the ground” method, the density of bentonite suspension, the distance between the trench and the foundation of the building, the load on the base of the foundation. In the medium technological sediment with the open method of work is estimated at about 60% of the total fixed value. Results. Technological deformations depend on three groups of factors: external, design and technological. External factors include engineering-geological and hydrogeological conditions of the construction site, as well as the stressstrain state of the soil massif. Design factors cover the space planning and design parameters of the constructed structure, which have an impact on the technology of work. Discussion. Technological factors determined by the characteristics and technological features of the equipment used, technological parameters of work production and quality control of their performance. In this regard, in order to provide feedback between the quality control of geotechnical construction and the safety of the surrounding development, it seems appropriate to understand under the term “technological deformations” deformations of the foundations, foundations and structures of buildings from technological influences in the construction process. Conclusion. In the presented work, the factors and parameters affecting the magnitude and scale of technological precipitation are highlighted. On this basis, proposals have been formulated for the elaboration of the concept of “technological sediment” in order to effectively control the quality and ensure the safety of the underground works carried out.

Number of views: 368

Ecological and biological aspects of oak forests formation on uplands and flat landscapes in Lower Volga region

Sergei N. Kryuchkov, Andrei V. Solonkin, Alexandra S. Solomentseva

The article presents data on the current topic of conservation and reproduction of oak forests in the arid conditions of the Lower Volga region on various relief elements. The article contains the result of long-term studies of oak forests of the Lower Volga region, the main predominant species of which is the petiolate oak (Quercusrobur L.). It was found that on soils of the Lower Volga region poor in humus composition with dissected relief and difficult weather conditions, the plantations of the petiolate oak fully justified themselves. It was revealed that oaks have good growth on chestnut, light chestnut and chernozem soils, and moderate on sandy, biologically stable, moreover, species with a high content of chlorophyll show the best performance. It was determined that the most effective way to create oak forests is to exclude 25-40% of the parent trees that showed the worst results during research. Otherwise, the plantings may face a decline in radial growth, loss of part of the crown and often shrinkage. Рurpose of the research. Bio-ecological assessment of species of the genus Quercus, aspects of the formation of oak forests on uplands and flat landscapes for afforestation in arid conditions of the south of the European territory of Russia. The object of research was the plantings of the pedunculate oak (Quercusrobur L.), which has an extensive range. Observations were carried out in the Volgograd region in the arboretum collections of the Federal Research Center of Agro-ecology of the Russian Academy of Sciences, at the Shemyakinskaya dacha – the oak grove of the Uryupinsky forestry, geographical oak cultures in the Oktyabrsky forestry, genetic and breeding complexes of oak in the Novoanninsky forestry, in the Rossoshansky forestry of the Voronezh region, the system of protective forest plantations in the Bogdinsky forestry of the Astrakhan region and the Elistinsky forestry of the Republic of Kalmykia. Research methodology. The water content in oak leaves was determined by the weight method by the hour during the day (1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 12 h, 24 h). Weather conditions and oak habitats were studied using the sites "Climate monitor" and "Agroatlas". The typology of forest growing conditions within the ALMR was characterized taking into account the forest suitability of soils developed by VNIALMI (now the Federal Research Centre for Agro-ecology, Complex Reclamation and Protective Afforestation). Based on the analysis of the results of all experimental materials, an integral indicator of the frost resistance of prototypes and control was calculated. Individual indicators of reproductive processes of clones were compared with the characteristics of control trees, revealing their correlations. The chlorophyll content was measured using the MS-100 device. Statistical data processing was carried out in the programs Statistica and Fractan. Research results and discussion. The intensity of growth of this species is determined by the geographical environment and the conditions of the place of growth. According to the results of the research, the petiolate oak showed excellent ecological and geographical plasticity and the ability to grow and develop in various conditions – from fine-grained leached sands of the Astrakhan and Elista experimental stations to light chestnut and dark chestnut soils of the Volgograd region, chernozem soils of the Novoanninsky and Uryupinsky forestry. The best growth and development were distinguished by the plants of the petiolate oak in conditions of macro-subsidence with dark-colored humus soils. A high percentage of oak trees with good condition were noted by the authors on micropropagations, meadow-chestnut slightly saline soils. There were no oak trees in good condition on flat, settled areas with the presence of saline spots. In the southern part of the Lower Volga region (Elista), oak

Number of views: 345

The Methodology of Inventory of Geological Heritage Objects as a Tool for Managing Geoparks

Ekaterina A. Bogdan, Larisa N. Belan, Irina V. Frolova, Ayrat F. Galiev

Using the example of the UNESCO Global Geopark "Yangan-Tau", the article presents a methodology for inventorying geological heritage objects as part of the natural heritage. The mechanism for assessing their scientific, educational and tourist significance is disclosed, the geoconservation is substantiated. The objects of geological heritage are ranked according to the value of the international, national, regional and local level. The application of the developed methodology will allow regional geoparks to approach the criteria indicators of UNESCO global geoparks. Introduction. UNESCO Global Geoparks demonstrate a model of effective management of the territory on which they are located. The status of the geopark is confirmed by seven criteria established by the UNESCO International Program on Geoparks and Geosciences. The first two of them are implemented, among other things, by conducting a detailed inventory of geological objects. The aim of research is to develop a methodology for the inventory of geological heritage objects (geo objects) of regional geoparks based on the assessment of their scientific, educational, tourist, environmental significance and the geoconservation in order to approach the criteria indicators of UNESCO Global Geoparks. Methodology. The inventory methodology involves an expert assessment of the scientific, educational and tourist value of objects, the geoconservation, the allocation of criteria for evaluating scientific, educational, tourist significance and the geoconservation, the development of indicators to determine the level of value. Results. The methodology was tested on the basis of geological heritage objects presented in the nomination dossier of the Yangan-Tau UNESCO global geopark in the Republic of Bashkortostan. The methodology revealed that over 60% of geological heritage sites have high scientific and educational significance. More than 30% of geosites have tourist significance. 12.5% of geosites require protection and preservation measures. The results of the application of the methodology demonstrated that international and national geosites have high scientific and educational significance. They are characterized by a better level of security, which guarantees the absence of significant threats. Objects of regional and local importance have medium and low scientific value, although their educational significance is quite high, and for tourists it varies between high and medium levels. Conclusion. The possibility of a regional geopark joining the UNESCO network of global geoparks is conditioned by compliance with the criteria approved by the UNESCO International Program on Geoparks and Geosciences, including various aspects of sustainable development of the territory. The methodology of inventory of geological heritage sites will allow regional geoparks to identify their strengths and weaknesses in order to approach the criteria indicators of UNESCO Global Geoparks.

Number of views: 331

Estimated impact of temperature conditions on deep pits natural ventilation in the Arctic

Semyon G. Gendler, Ivan A. Borisovskiy

The Arctic zone of Russia is a territory where such minerals as gold and other precious metals are concentrated. Most often, the development of such deposits is carried out by an open method. The conditions hindering its use should be considered: the depth of distribution of permafrost and significant amplitude of changes in atmospheric air temperature during the year, month and day. The consequence of the alternation in depth of temperature zones may be the formation of recirculation zones in which harmful substances accumulate. Purpose of work. Study of the formation of velocity and temperature fields in a quarry under natural ventilation, taking into account the complex dynamics of atmospheric air temperature. Research methods. Systematization, generalization and analysis of theoretical and experimental studies in this area, including those carried out at the considered fields. Analysis of the results of mathematical modeling of aerodynamic processes in a quarry. Results. It is noted that to assess the peculiarities of formation of the mine atmosphere parameters it is sufficient to carry out only mathematical modeling of aerodynamic processes allowing to define the conditions of temperature inversions formation and dimensions of recirculation zones being potentially dangerous for accumulation of pollutants. The methodology of aerodynamic processes modeling taking into account the geometry of the pit space, temperature gradient, speed and direction of the wind flow is proposed. It is shown that at positive and negative temperature differences for the two investigated air media the development of recirculation movement zones of air masses that assure the accumulation of pollutants which in turn leads to reduced efficiency of natural ventilation in the pit, is characteristic. The conclusion has been made on the necessity to apply additional engineering measures during the period of inversion formation with negative temperature gradient in order to normalize the pit air parameters.

Number of views: 372

An integrated approach to the development of the raw material base of the mining region with the use of resource-reproducing technologies

Alexander S. Kopylov, Ada K. Dzhioeva, Yuri I. Kondratyev

Introduction. The constant increase in the consumption of mineral resources leads to the depletion of available reserves and a sharp increase in the depth of field development. In addition, reserves that were previously classified as off-balance sheet and the development of which is economically inefficient at the time of the assessment of technical and economic calculations are involved in the development of minerals: low metal content; location within water protection zones, settlements, structures, agricultural facilities, nature reserves, monuments of nature, history and culture. Involvement in the development of areas of deposits with a low content of a useful component in ore increases the costs of extraction, transportation and processing, as well as the formation of more man-made waste. The main way to ensure the sustainable development of the mining region is the use of mineral deposit development systems with a hardening bookmark and the involvement of man-made waste in a closed production cycle. The use of geotechnology with a bookmark helps to increase the completeness and quality of the extraction of reserves of the deposit, protects the hydrogeological regime and reduces the degree of crack development in the underworked array, which leads to the preservation of the water-proof thickness and protects the daytime surface from collapse. Geotechnology with a bookmark allows you to work out previously abandoned targets, which increases the mineral resource base of the mining enterprise and increases the life of the mine and allows you to solve the social issue of the region where the mining enterprise is the city-forming. The use of man-made waste from mining and processing and metallurgical enterprises in the preparation of the laying composite leads to their disposal. Utilization of man-made waste with geotechnology with a bookmark leads to a decrease in the volume of man-made storage facilities, which reduces the cost of their creation and maintenance. All this contributes to the implementation of the concept of waste-free production, the integrated development of natural and man-made resources, the sustainable development of the mining region and the reduction of the impact of mining and metallurgical industries on the environment. Purpose of research. Introduction of technologies that ensure the completeness of mineral extraction and safe mining operations with minimal environmental impact. Research methods. G eneralization of theoretical and experimental studies carried out by scientists in this field, synthesis of literary and patent data, analysis and summary of previously performed own research, comparison of theoretical calculation data on mathematical models with the experimental results obtained, application of current state standards, approved research methodology, use of calibrated and serviceable equipment. Materials were activated in a DESI-11 laboratory disintegrator, compression samples were tested on a PI-2000-A test press, and the reliability was confirmed by the repeatability of the results with a sufficient number of experiments. Research results. The possibility of replacing the traditional components of the laying composite with man-made waste without loss of regulatory characteristics and improvement of its rheological properties is substantiated. The necessity of applying mechanical activation treatment of the components of the laying composite in order to improve its rheological characteristics and the strength of the array after solidification is proved. The demand for resource-reproducing technologies that allow the most complete use of the technogenic mineral resource potential of the mining and processing enterprise, which will lead to a multiplicative ecological and economic effect, has been confirmed. It is established that the sustainable development of the mining and processing region is impossible without highly eff

Number of views: 312

On assessment and management of hydrological risks during spring flood in the River Arpa Basin (Republic of Armenia)

Varduhi G. Margaryan, Ekaterina V. Gaidukova, Igor O. Vinokurov, Nikolay A. Reshin

Introduction. Issues of formation of maximum expenses and their forecast, risk extreme flow rates on the rivers of Armenia represents a significant interest for consumers of water resources. The works of scientists of the Republic of Armenia are devoted to the solution of this problem: (Vardanyan T. G., Muradyan Z. Z., 2014), forecasting the maximum water flow for the Jermuk hydrological station on the Arpa River (Misakyan A. E., Azizyan L. V., Azizyan A. O., 2014), assessment of long-term fluctuations of the maximum runoff of rivers in the mountainous territories of Armenia in the context of global changes climate (Margaryan V. G., Ovcharuk V. A., Goptsy M. V. Borovskaya G. A., 2020). This paper analyzes the risks of extreme spring runoff river flood Arpa (Republic of Armenia) related to degree assessment the danger of flood waves. Problem solving can help prevent economic damage and loss of life, and raise issue of extreme runoff risk management. Unlike listed works, this study uses longer series of actual observations and a certain section of the river. Purpose of research. Assessment and management of hydrological risks during the period spring flood in the river basin Arpa. Methods. The work used the methods: of mathematical-statistical, extrapolation, analysis, analogy, correlation. Results. Correlations between the values of the modulus of extreme costs 1 and 10 % security and weighted average height drainage basin, as well as the relatively close relationship between the average values of extreme costs for the periods 2001–2020 and 1981–2000 biennium, integral curve of extreme flow rates of floods in the section Yeghegnadzor of the Arpa River. These dependencies can be used to preliminary estimates of the maximum runoff of the spring flood unexplored rivers of the considered territory. To manage and planning of extreme water resources, multifactorial dependencies that can be applied when making forecasts. The rate of extreme flow rates of the spring flood has been calculated, coefficients of variability (Cv) and skewness (Cs), absolute maximum costs of various security. Conclusion. Average values of extreme water flow rates of the river. Arpa for the period 2001–2020 mostly inferior or slightly higher than average values for the period 1981–2000. In the Arpa river basin from 1981 to 2020 year mainly there is a tendency of decreasing extreme river flow, that is, the degree of risk of extreme expenses.

Number of views: 328

Physico-chemical analysis of the soil cover of technogenically disturbed territories of Kuzbass

Maria A. Osintseva, Irina S. Milentyeva, Yulia V. Golubtsova

As a result of coal mining, the natural landscapes of the Kemerovo region are involved in the process of global
technogenic transformation. As a result of open-pit coal mining, catastrophic changes occur in ecosystems, which are accompanied by the destruction of the litho logical basis, degradation, transformation and displacement of huge tracts of soil cover. The aim is to study agro physical, agrochemical, sanitary and epidemiological indicators of soil samples of technogenically disturbed territories of Kuzbass. Objects of research. Samples of the surface layer of the external rock dump of LLC "Korchakolsky Section" the dump rock and the surface layer of the nearby territory, of the forest belt of the processing plant of LLC "JV "Barzassky Partnership" and the Taldinsky coal mine. The samples of undisturbed lands selected near the museum-reserve "Tomskaya Pisanitsa" were used as a reference. Methods. Agro physical (hygroscopic humidity, wilting humidity, soil density, soil porosity) and agrochemical (water and salt pH, total alkalinity, hydrolytic acidity, sum of exchange bases, dry residue, content of Cl–, SO₄2–, HCO3–, NO3–, Ca2+,Mg2+, Al) analysis of selected soil samples, including the content of pollutants of anthropogenic origin. The sanitary and epidemiological indicators of the samples were studied. Methods of chemical and instrumental analysis (electrochemical, chromatographic, molecular absorption spectroscopy) were used for research. Results. The analysis of the degree of technogenic disturbance of the studied landscapes is carried out. Samples of LLC JV "Barzassky Partnership" can be attributed to sandy loam soils of a slightly alkaline type. The nickel content exceeded the MPC by 1.26 times; the BGCP index by 25.25 times. Samples of the Korchakolsky section are attributed to sandy soils of a slightly alkaline type. The content of mobile phosphorus exceeded the MPC by 3.40 times, zinc by 1.1 times, nickel by 1.22 times, arsenic by 2.15 times; the BGCP index by 29.41 times. The samples of JSC Taldinsky Coal Mine are classified as sandy loam with a neutral reaction. The content of the mobile form of phosphorus exceeded the MPC by 5.22 times; nickel by 1.5 times; arsenic by 1.67 times. The samples of the reference soil are attributed to clay soils of a slightly alkaline type. The content of the mobile form of phosphorus exceeded the MPC by 2.27 times; nickel by 1.17 times, the BGCP index by 62.62 times. Conclusions. Based on the analysis of the composition of dump and quarry landscapes of technogenically disturbed territories of the Kemerovo region, detoxification of soils with the use of biological reclamation is recommended. 

Number of views: 349

Sensory taste assessment of Gayo Volcano Arabica Coffee of variety using the analytical hierarchy process method

Rahmat Fadhil, S. Safrizal, Anzar Muhir

Volcano arabica coffee is one of the best coffee derived from Gayo Highlands, Aceh Province, Indonesia. That coffee was cultivated in a volcanic region, therefore as known as Gayo volcano arabica coffee. Several varieties from Gayo volcano arabica coffee were included Borbor, Timtim, and P88. Gayo volcano arabica coffee was a low caffeine coffee with a taste exceeding the Blue Mountain coffee from Jamaica which was determined using sensory assessment. This study aims to conduct a sensory taste assessment from Gayo volcano arabica coffee variety using the analytical hierarchy process (AHP) method. The AHP method is one of the easiest methods to produce an output calculated based on the input and weight value. Sensory assessment criteria have consisted the flavour, sweetness, aftertaste, body, and acidity. The preference for the best criteria based on the panellists was included taste (0.280), then the sweet criteria (0.253), after tasting (0.212); body (0.140); and acidity (0.115). The estimation was tested with a consistency ratio under 0.1 (10%). The results of the sensory assessment of the acceptance of Gayo volcano arabica coffee products showed that the P-88 variety with full-wash processing (0.206) was the product with the highest approval. Then followed by the Borbor variety with full-wash (0.176) and semi-wash processing (0.166), then the Timtim variety with semi-wash (0.166) and full-wash processing (0.164). The P-88 variety with semi-wash processing (P88) was the product with the lowest level of acceptance by the panellists. This finding was most important for the commercial development of arabica volcano coffee in the future. The varieties associated with the highest acceptable taste became the better necessary varieties to cultivation and developt for farmers and agroindustry.

Number of views: 335
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