Analysis of dielectric losses in chromespinelide samples from the ophiolite complexes of the Urals

Relevance is determined by the need to search for scientifically based criteria for the identification of chromite mineralization. The purpose of this work is to study the features of dielectric losses and their temperature dependence of ore-forming chromespinelides in relation to the chemical composition and phase transformations in their structure. Research methodology. To study the dielectric properties of chromespinelides, samples were prepared in the form of a cube with an edge of 0.02 m (two cube samples were prepared from each sample). Measurements were performed in an open system at atmospheric pressure. Dielectric losses were measured with a two-electrode setup every 10 degrees in the temperature range 20–900 °C. Heating rate is 4 deg/min. The temperature in the system was determined with a platinum-piatinum-rhodium thermoeiectric coupie at 0.01 m from the sampie. As a measuring device for determining the tangent of the angie of dielectric losses (tg δ) at alternating voitage, the “Digitai L, C, R Meter” E7-8 was used. The operating frequency of the device is 1 kHz. In the initial sample and the duplicate sampie after its roasting to 900 °C, the content of oxides of ferrous and ferric iron was determined. The reiative change in the ratios of oxide and ferrous iron in the initial sample and in the dupiicate sample after roasting was compared with the position of the maximum dielectric losses on the temperature scale. Results. Samples of chromite ore from various deposits and ore occurrences of the Urals were studied by physical, physicochemical, mineralogical and petrographic methods. The temperature dependences of dielectric losses of 21 samples of chromite ore, consisting of 80–90% of chromespinelides, were obtained. All curves clearly show the maximum dieiectric iosses. This indicates that the losses are of a relaxation nature. The position of the maximum on the temperature scaie is different for the studied chromespinelides and is mainly associated with a change in the ratio H. H value is the relative change in the ratio of oxide and ferrous iron FeO/Fe2 O3 in a chromespinelide sample during its heating to 900 °C. The position of the maximum dielectric losses for the studied samples varies from 450 °C (sampie 1 – massive chromitite from the Podenny mine III deposit – Alapaevsi<y massif) to 842 °C (sample 21 – massive chromite ore from the Tsentrainy deposit – Ray-lz massif). In this case, H vaiue varies from 1.61 to 11.14, respectively. A relationship was revealed between the position of the maximum dieiectric losses on the temperature scale of the studied samples of chromite ore and the parameter H. Conclusions. The above results in combination with other physicochemical parameters can be used as an indicator of a rapid assessment of the type of mineralization.

Zonality of ore-forming chrome spinels of medium-chrome and aluminous chromitites of the Voikaro-Syninsky massif

Relevance of the work. The conditions for the formation of chromium ores in alpine-type ultramafites remain a topical subject of research. In recent years, scientific papers have focused on the issue of changing the chemical composition of ore-forming minerals and chromium ores under the influence of deformation and dynamic recrystallization processes accompanying metamorphism. The results of such studies make it possible to formulate a new model of the formation of chromium mineralization taking into account a significant amount of geological data indicating that alpine-type ultramafic rocks are “mantle tectonites”. In our work, we have studied zonal ore-forming spinels from chrome ores of the Polar Urals. The results of the study make it possible to associate the formation of chemical zoning in minerals and ore bodies with recrystallization under the influence of stress tension. Purpose of the work – study of the conditions for the formation of chemical zoning of chromium spinels from alumina and medium chromium ores of the Voikaro-Syninsky massif. Results. Zonal ore-forming spinels from medium-chromium and aluminous chromitites of the Voikaro-Syninsky massif (Polar Urals) have been studied. It was found that replacement rims are developed along the grains of oreforming spinels with an increased content of Cr2 O3 and an oxidation state of iron in relation to the core, as well as a reduced content of Al2 O3 . The oxidation state of iron in the rims of most grains does not exceed the values typical for unaltered ore-forming spinels. T–fO2 parameters of zoning formation in spinels were determined by oxythermobarometry. Comparison with zoned chrome spinels of the Golyamo Kamenyane massif (Bulgaria). Conclusion. Metamorphic transformations of alumina and medium-chromium chromitites of the Voikaro-Syninsky massif, occurring under subcrustal conditions under the action of directional stress at relatively constant T–fO2 parameters, lead to an increase in the chromium content of the ore mineral.

Development of a model of a ground-penetrating radar section of a frozen rock massif with a crack

Revelance of the work. The presence of cracks significantly affects the physical and mechanical properties of rocks, which should be taken into account when planning mining operations and building mining facilities. In the conditions of the spread of permafrost rocks, characteristic of northeastern Russia, the study of fracturing is possible by the GPR method, which is used to assess the structure of rock massifs in placer deposits. The criteria for detecting cracks based on the features of wave georadar fields are currently known, and the main problem that prevents the full use of the georadar method for studying cracks in subsurface layers of rocks is the labour-consuming nature of processing and interpreting data from georadar measurements. Purpose of the work – to determine the patterns of cracks occurrence in frozen rocks in GPR wave fields. Methodology of the work. Based on the results of longstanding field work at the developed areas of alluvial diamond deposits in the Anabar region of the Republic of Sakha (Yakutia), the main elements of the radarogram structure were determined and presented in the form of a single formula. The developed formula is implemented in programs in the SCM Matlab and the results of its execution are compared with the results of modeling in the gprMax system. Results of the work and the scope of their application. The resultant formula describes the main elements of GPR radarograms quite correctly, which confirmed their comparison with the obtained model data. The correlation coefficient between the obtained matrices (Matlab and gprMax) without the low-amplitude values of multiple reflections was 0.91, which shows the identity of the structure of GPR wave fields. Conclusions. The studies carried out have confirmed the possibility of a mathematical description of the ground penetrating radar wave field obtained by sounding a mass of frozen rocks with a crack. The high correlation coefficient showed the adequacy of the developed radarogram model, which will be finalized taking into account the directional diagrams of existing georadars.

Features of the material composition and possible technologies of pyrite cinders processing

Relevance of research is determined by the need to study for subsequent rational processing of technogenic mineral raw materials – pyrite cinders formed during firing pyritic concentrates for the production of sulfuric acid. Topical issues here are the determination of their chemical and mineral composition, morphology of particles, which predetermine possible technologies of their processing. Purpose of research – study of the material composition of pyrite cinders of the dumps of the Kirovgrad coppersmelting plant, features identification of the composition of different-age dumps. Methods of research. In the selected samples of pyrite cinders, their chemical composition was determined, the morphology of particles was studied by photographing them using the Philips XL-30 electron microscope equipped with an energy dispersive spectrometer (EDS), and possible processing technologies were analyzed. Results. It was found that pyrite cinder of the old dump (no. 1) is characterized by low SO3 contents and low values of losses when firing relative to dump no. 2, which is determined by the oxidation of residual pyrite, as well as CaO and higher Fe2 O3 contents. The study of the morphology of pyrite cinders microparticles showed that they have an irregular shape, globule shape and spherical size from 40 μm to 2 mm. Some known technologies of purple ore processing are considered. Conclusion. The morphology of pyrite cinders particles and their chemical composition were determined as a result of the research. Taking into account the research results and morphostructural characteristics of cinders material, in particular, it is obvious that a number of technologies can be chosen for their complex processing; at the same time this determines further directions of their research, for example, the study of valuable impurity elements in them and their behavior in the process of changing the material of the dumps.

Legal support for the restoration of lands disturbed by mining operations: Experience in the Russian Federation

The effectiveness of the restoration of lands disturbed by mining operations largely depends on the perfection of the legislation regulating this process. The purpose of the study is to identify evolutionary changes in the legal framework for reclamation and bottlenecks that require the improvement of legal acts. Research methods – scientific generalization, comparisons, analogy method, comparative and evolutionary analysis. Результаты. The relevance of reclamation in modern conditions has been substantiated, which is confirmed by the basic requirements of sustainable subsoil use and the Sustainable Development Goals (SDGs). The information concerning the legal support of reclamation is generalized and analyzed, the stages of this process are determined; setting back by a decade in the formation of legal support for reclamation in Russia of the Soviet period from foreign countries is identified. In Russia, the initial stage is attributed to the period of the 1950s– 1970s, when legislative documents were sporadic and did not practised on such a systematic basis. The period of the 1970s–1980s was defined as the main one, during which there was the approval of the “Basic provisions on the reclamation of lands disturbed during the development of mineral deposits and peat, conducting geological exploration, construction and other works” (1977), which have been successfully used for almost 20 years. At the same time, GOSTs and standards regulating reclamation began to operate. The following were subject to regulation: financing, accounting for the costs of reclamation work, compensation for any damage caused by the recipient, transfer of reclamation lands to land users, etc. Since the 1990s, there has been a certain decline in research focused on reclamation, although this period is characterized by the approval of quite important legislative acts, including the “Basic Provisions on Land Reclamation, removal, conservation and rational use of the fertile soil layer” (1995). Reclamation provisions are reflected in a number of federal laws and strategic documents. The highly anticipated government act defining the procedure for land reclamation and conservation was adopted in 2018. Deficiencies in the existing legislation regulating reclamation were identified, requiring amendments and additions to the latter. First of all, this concerns the Federal Law called “On Subsoil”, as well as the regulation of the financing of reclamation. Conclusion. Improving the legal framework for reclamation work will undoubtedly help to increase the efficiency of this process.

Methodological aspects of regional metallogenic analysis

Relevance and purpose of the work are due to the need to formulate the conceptual base and essence that determine the methodology of regional metallogenic analysis. Results. The fundamental provisions that make up the methodological and conceptual-semantic basis of the regional metallogenic analysis have been determined and concretized. The conceptual basis of regional metallogenic analysis is the provision that the ore (deposit) is included as a natural component in certain structural-material associations (or complexes), i.e., in certain formations of igneous, sedimentary and metamorphic rocks. They are objectively existing and actually mapped geological bodies, which are expressed both in the form of stratified (series, formations, strata, packs, horizons) and intrusive (massifs) formations. On their basis, structural-formation (structuralmetallogenic) zoning is carried out. An important feature of magmatic, sedimentary and ore formations is their recurrence in the geological history of mobile belts, which confirms the concept of the conservatism of metallogenic processes in the geological history of the Earth. At the same time, along with repetitive ones, there are magmatic, sedimentary and ore formations formed in the geological history of the Earth only once. Lateral and vertical rows of rock and ore paragenetic associations are characterized. Examples of Caledonian and Hercynian lateral ore-formation series of the Urals are given. The main provisions of the quantitative assessment of the predicted resources of the predicted types of minerals are formulated. Conclusions. The regional metallogenic analysis consists of the following components: petro-lithoformational analysis, structural-formational zoning which is adequate to structural-metallogenic zoning, paragenetic analysis of mineral associations and geological-industrial typification of various-scale occurrences of a mineral, and quantitative assessment of expected mineralization predicted resources.

The challenges of Industry 4.0 and the need for new answers in the mining industry

Relevance of the work is due to the need for further modernization of the economy of the Russian Federation, which involves solving both basic theoretical and applied problems of the domestic mining industry. This circumstance largely determines not only the state of the state’s production resources, but also its scientific and technical potential. The global trend in the development of mining operations in the world is mainly determined by open pit mining of raw material resources. Open pit mining is characterized by an increase in the volume of processed rock mass, improved production processes through the use of advanced technologies, which entails the use of high-capacity mining machines. The main problems of open-cut mining are the following: complex mining and geological and mining-technical conditions; depletion of the mineral resource base; and constantly changing environmental conditions. All this leads to an increase in the cost of mining and a decrease in the competitiveness of the products of mining companies. Objective of the work. To establish the need to modernize traditional technologies in open pit mining with the possibility of integrating the main ideas of Industry 4.0. Research methodology. When solving the set tasks a complex approach was used, including: scientific analysis and synthesis of previously published research, analytical studies, laboratory experiment and observations of the work of open-pit excavators in real operating conditions. The methods of mathematical statistics include system analysis and modeling with the use of information technologies form the methodological basis of the research. Results. This paper deals with the issues of modelling the cab of a quarry crawler excavator to meet the technical requirements for the excavator cab in protecting against tipping and rock impacts. Model setup and analysis of simulation results after loading are performed using Autodesk Inventor software. An optimal finite-element model of an excavator operator’s cabin has been developed to assess the effectiveness of its structural protection. Conclusions. Implementing the core ideas of Industry 4.0 is a complex scientific and technical challenge. Its solution is connected with significant economic costs, including modernization of mining equipment, infrastructure, as well as changes in the technology of open-cast mining. The implementation of complex automated control systems and practical application of the latest information and geoinformation technologies will unambiguously give high estimated figures and have high applied potential, and ultimately ensure safety of open pit mining, increase of efficiency and productivity, possibility of mining in regions with complex mining and geological and mining-technical conditions.

Analysis of the components of the water balance of river basins during the formation of the Selenga and Onon rivers

The purpose of the study is to study in detail the components of the water balance of the river basin that affect the amount of flood runoff. The objects of the study are the rivers of Eastern Siberia – Selen-ga and Onon. The work is based on the materials of standard long-term observations of the hydrometeorological network of the Trans-Baikal UGMS, and the databases of the GPCC Center for Atmospheric Precipitation Climatology were used. Relevance. Floods are characterized by non-periodic and short-term rise in the water level in the river, which can lead to catastrophic consequences and major material damage. The methodology of the study consists in a complex hydrological and geographical analysis of the processes of flood runoff, namely, the method of water balance. In the course of the study, a geographical analysis of flood factors in the conditions of the steppe, forest-steppe and taiga zones of Eastern Siberia was carried out. During the thirty-year period of hydrometeorological observations in the basins of the Selenga and Onon rivers, graphs of changes in water flow over time (hydrographs) were constructed and genetically related values of flood runoff and flood-forming precipitation were calculated. The combination of landscape characteristics and climatic features determines the hydrological indicators of the river in its various sections, forming a general picture of the hydrological indicators of the river network as a whole. Conclusions. According to the ratio of the maximum water flow rates of various origins, spring floods and summer floods in the Selenga and Onon river basins, groups of rivers were identified according to the predominant genesis of the maximum flow. For the rivers of the Selenga and Onon basins, fluctuations in river flow and atmospheric precipitation are studied, and their relationships with the characteristics of atmospheric circulation are established. Both rivers under consideration are transboundary, which imposes certain difficulties on the ability to solve problems of determining and predicting hydrometeorological processes.

Financial strategy for large coal producers

Relevance of the study. In the current context, there are quite negative trends in the coal industry: instability of the situation in the coal markets and increased competition, which creates risks of financial instability of enterprises. In these conditions, it is important to develop a financial strategy aimed at fulfilling promising production tasks. The purpose of the study is to substantiate the financial strategy of large coal producers. Research methods – scientific generalization, logical analysis, methods of comparison and analogies. Results of the study. The key points of the financial strategy have been identified: the goal of the effective development of a coal producer; time – long-term benchmarks; mechanisms – financing; directions – the implementation of financial activities; conditions – external and internal environment. The development of a financial strategy is based on a system of financial ratios used to form an acceptable structure of working capital. Calculation formulas are proposed to determine the required amount of cash, short-term financial investments, accounts receivable and the amount of stock in the composition of working capital. The quantitative values of these indicators that are acceptable from the point of view of the financial strategy have been determined: not less than 25%, not more than 25%, not more than 50%, respectively. The set of financial ratios for the formation of an acceptable ratio of own and borrowed funds, their calculation formulas and recommended values are recommended. The values of the coefficient Kз/с of the ratio of borrowed and own funds, which determines the possibility of using borrowed funds, are given. In direct connection with Кз/с, the autonomy coefficient is considered and its reasonable values are justified. Conclusions. The specified conditions for the formation of a financial strategy are primarily related to large coal producers, where there are opportunities for revenue growth and a reduction in the duration of the production cycle. The proposed acceptable values of financial ratios will make it possible to achieve sustainable financial independence of enterprises and ensure their effective development.

Research of the properties of rocks during fragmenting and crushing in mechanical mills

Relevance and purpose. The systemic crisis in the mining industry has weakened the provision of the industry with proven reserves of the main types of minerals, which has made the search for technological solutions in order to restore the lost potential of the mineral resource base. Methodology. Theoretical studies of the movement of the grinding charge in the grinding chambers of planetary mills are based on the postulate of the equivalence of the forms of movement of the charge in mills. Grinding equipment of a new technical level is being improved in the direction of increasing the intensity of the effect of grinding bodies on the crushed material. The aim of the study is to increase the intensity of the impact of grinding bodies on the crushed mineral raw materials while minimizing the energy consumption of processing processes. The goal is achieved by integrating analytical and experimental studies with elements of engineering forecasting and modeling of the results. Results and scope. The results of studying the properties of rocks and their changes as a result of crushing and grinding in mechanical mills are presented. Information about devices for measuring the parameters of shock pulses and the practice of their application is systematized on the example of geological differences of rocks. Bench studies have confirmed the theoretically substantiated phenomenon of shock pulse amplitude suppression. The role of the processes of crushing and grinding in mills in the technological chain of waste-free utilization of the tailings of the concentration of chemically exposed ores is detailed. Сonclusions. The phenomenon of increasing the intensity of the impact of grinding bodies on the crushed mineral raw materials with the same energy consumption of processing processes can be used in the modernization of technologies for the development of mineral deposits.