Volume 335, Nº 9 (2024)

Relevance. Despite the use of alkali stripping technology for processing monazite concentrate in industry, this method has a number of limitations, such as low efficiency of concentrate stripping, the need to use a large excess of alkali and a long process time.

Aim. Improvement of existing technology to overcome these limitations.

Methods. Fusion with NaOH under pressure and fusion with NaOH combined with ball milling, as well as fusion with NaOH using high intensity ultrasound. High-intensity ultrasound has long been studied and used in industry to intensify leaching/alloying in various applications to increase efficiency and speed in leaching for copper, vanadium, nickel, bauxite and uranium ores. This article is devoted to studying the influence of high-intensity ultrasound on the efficiency of opening monazite concentrate with NaOH solutions. Experimental data were obtained using mass spectrometric, X-ray diffraction and ICP-OES analysis methods.

Results and conclusions. The optimal conditions for leaching batches of samples weighing from 100 g to 1 kg were determined. The authors have carried out the research on the separation of radioactive elements and impurities in a solution of rare earth chlorides, obtaining a solution of rare earth chlorides purified from radioactive components and impurities. It was shown that ultrasonic exposure eliminates the disadvantages of traditional fusion technology with NaOH, which can be used for deep processing of Vietnamese monazite concentrate. The conditions for obtaining REE chlorides from a previously opened monazite concentrate are given.

Relevance. The need to study the features of aerogenic effects of the Norilsk industrial complex on the natural environment. Aim. To study the features of the aerogenic effects of the Norilsk industrial complex in the south-southwest zone at a distance of 40–60 km using lichens Cladonia rungeferina and Cetraria sp.

Objects. Soil, lichens Cladonia rungeferina and Cetraria sp.

Methods. Soil and lichen samples were taken 40–60 km south-southwest of the Norilsk Industrial district. Sampling was carried out according to the scheme of two profiles with a length of 14 and 20 km. The samples were analyzed using a set of methods consisting of X-ray fluorescence (S4 Pioneer Bruker AXS), atomic absorption methods (KVANT-2A, Julia-5K) and induction-coupled plasma mass spectrometry (ELEMENT-2) in the laboratory of the GIN RAS, Moscow. The concentration of Ti, V, Ni, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Rb, Cd, Sb, Ba, La was determined.

Results. The authors have obtained the data on the concentration of the 21 elements in soils and lichens. The paper demonstrates the calculation of distribution of elements in soil and lichens relative to the concentration in the upper part of the continental crust. The authors calculated the enrichment factor for Mn, Ni, Cu, Hg, Pb and estimated the distribution of this coefficient for both profiles. It is shown that the technogenic component of the aerogenic effect for Mn, Ni, Cu, Pb to the south-southwest of the Norilsk industrial complex at a distance of 40–60 km is practically absent. The increased values of the enrichment factor in lichens for Hg are explained by a combination of two factors – the constant presence of mercury in significant concentrations in ecosystems and tundra fires that took place in this zone in 2019–2020, which ultimately led to the re-deposition of Hg in the burnt areas.

Relevance. The need to ensure safe working conditions in the working areas of underground mines. Stagnant zones with low air velocities can be formed in large section blind heading behind the ore bulk when ore is shipped by mining machines. There is a possibility of the formation of local gas accumulations and their abrupt removal later in such stagnant zones due to the unsteadiness of accumulation and transfer of gas impurities in a blind heading. A sharp removal of gas will lead to contamination of the load-haul-dump operators’ workplace.

Aim. To identify removal of exhaust gases in large section blind headings in conditions of changing ore load size.

Objects. Large section blind headings with of complex geometry.

Methods. Three-dimensional numerical simulation of unsteady turbulent flow of a gas-air mixture in the Ansys CFX, visualization and analysis of simulation data in the Wolfram Mathematica.

Results. The paper presents the results of mathematical modeling of ventilation of large section blind headings of complex geometry under conditions of changing ore load size formed during mining operations by the load-haul-dump machines with an internal combustion engine. It is shown that either a single vortex is formed that ventilates the blind headings space, or a stagnant zone behind the bulk ore, which is characterized by a relatively low intensity of mass transfer. Vortex formation depends on the height of the ore bulk. The authors have obtained the dependences of the change in the average concentration of exhaust gases at the outlet of the blind headings space on the operating time of the machine. They determined the dependence of the correction volume coefficient on the geometric parameters of the blind headings. An analytical model of the removal of gases from the blind headings space under conditions of changing bulk ore volume is obtained. The expression of increment in gas concentration on an operator’s workplace makes it possible to derive formula to find maximum time of load-haul dump operation in a stope such that gas concentration is never higher than maximum allowable concentration.

Relevance. Territorial planning of cities determines the reduction or prevention of possible or existing losses of the population, economic facilities and the environment from technogenic-natural hazards of different genesis. The effectiveness of planning regulations for urban development depends on the degree of validity of identification and forecasts of the occurrence and evolution of hazardous natural and technogenic processes in time and space. This, in its turn, is determined by the reliability of our ideas about the patterns of their formation and regional distribution.

Aim. To identify geological hazards and propose the main engineering and geological constraints in urban planning on the example of Gomel.

Objects. Natural and technical system "geological environment – technogenic impacts – hazardous natural and technoprirodnye processes".

Methods. Systematic approach to the analysis of patterns of formation of hazardous natural and technoprirodic processes in the city; numerical modeling of geofiltration and geomigration processes based on the geofiltration model "GOMEL".

Results. The most characteristic dangerous natural and technogenic-natural processes have been established on the example of the city of Gomel. Priority areas for the introduction of planning restrictions: tectonic situation; man-made flooding, were identified. Soil conditions are considered separately as one of the factors effecting the precipitation of natural and artificial bases under the influence of loads from civil and industrial buildings and structures. The authors have revealed the presence of disjunctive, as well as plicative in the form of flexures, age-varying and multi-scale dislocations forming the block structure of the upper part of the earth's crust of the city. It is shown that from the point of view of the stability of engineering structures, the absolute values of the velocities of long-period unidirectional block displacements are dangerous during long-term operation of structures located in interblock active zones. At the same time, short-period multidirectional movements in the active geodynamic zones of the articulation of blocks cause a change in the slope and bending of the foundations of structures. The paper introduces the engineering-geological features of the most common surface deposits: the terrigenous gray-colored formation of the Paleogene; glacial, periglacial and extraglacial formations of anthropogenic origin and their facies-genetic complexes. The authors identified the potential natural and technological hazards associated with the marked deposits. The paper demonstrates the causes and mechanisms of the formation of technogenic flooding of the city, as well as the genesis of the decrease in the deformation properties of moraine sandy loam with a technogenic increase in humidity. It is concluded that when establishing land use regulations for a city, as a rule, general measures cannot be taken, both for its entire territory and for certain stages of construction activity. The paper introduces the corresponding restrictions on the use of subsoil.

Relevance. As a result of the construction and operation of buildings and structures within the Abakan agglomeration, there is an activation of existing and the formation of new engineering and geological processes accompanied by accidental destruction of constructions. In order to minimize economic and socio-environmental damage, timely development of scientifically sound urban planning and architectural planning solutions is necessary. It would take into account the results of design studies of engineering protection of the territory from dangerous manifestations of engineering and geological processes. Generalization of the available survey results in order to typify the engineering and geological conditions of the urban area will optimize the construction development of urban areas, develop reliable schemes of engineering protection against the manifestations of dangerous engineering and geological processes.

Aim. To establish natural and anthropogenic factors that determine the activity of dangerous geological processes in the territory of the Abakan agglomeration.

Methods. Collection, systematization and analysis of available territorial geological, hydrological, hydrogeological, environmental information, results of engineering surveys.

Results and conclusions. At a qualitatively new level, a set of maps has been compiled on the factors that determine the development of dangerous geological processes. The authors have carried out a GIS analysis of morphometric indicators of the relief of the agglomeration territory: maps of the steepness and exposure of the slopes were constructed. The analysis of the collected data made it possible to establish the regional characteristics of the components of the geological environment and propose a zoning scheme for the territory for its construction development and engineering protection. The authors identified four taxa during zoning: territories favorable for construction that do not require significant engineering training; territories conditionally favorable for construction, requiring preliminary engineering training; territories conditionally unfavorable for construction, requiring significant costs for engineering training; territories unfavorable for construction. The boundaries of the taxa are based on the analysis of the geomorphological features of the territory. The conducted research was performed for the agglomeration territory for the first time.

Relevance. While performing the operation processes, the technological equipment emits vibration. Vibration is a consequence of increased dynamic loads in structural elements and interfaces between systems and their elements. The development of fatigue damage can significantly accelerate. Therefore, the solution of the problems related to reducing vibration levels is always relevant. Each type of protective system has a linear law of changing the stiffness. This does not allow the effective damping of low-frequency vibrations. Thus, the information review demonstrates the future of the research according to the creation of the vibration protection systems, constantly improving their parameters in the following aspects: minimizing overall dimensions and number of parts; increasing reliability, especially in resonant mode; providing the ability to operate in modes with low stiffness. The last factor determines the good damping of vibration emitted by the source.

Aim. To study the possibility of the vibration protection system development with quasi-zero stiffness with the ability to effectively dampen low-frequency vibrations.

Methods. Information and analytical review in the field of the research, search for the constructive solutions, preliminary design calculations and 3D modeling, description of the device being developed and its operating principles.

Results. The research presents the results of development of the vibration protection system with quasi-zero stiffness and a fragment of an information review of existing vibration protection systems. The authors indicated the main shortcomings specific to all vibration protection systems: relatively large sizes, large number of elements, insufficient operating frequency range. The authors proposed a constructive solution for creating a vibration damping system with a nonlinear law of change in stiffness. This solution allows eliminating the above shortcomings and providing the possibility of effective damping of low-frequency vibrations. The authors created the method for calculating the constructive parameters of a vibration damping system. An example of calculation is given in the paper. This system differs from existing vibration protection devices in its low stiffness and small dimensions, and a wide operating frequency range of vibration damping. The efficiency of the system operating with nonlinear and quasi-zero stiffness is proved.

Relevance. The need to study the forms of migration of chemical elements in the groundwater of flooded copper pyrite mines in order to correctly understand and predict their transfer and distribution in hydrogeochemical fields. Ground and surface waters are a complex mixture of substances in which, depending on pH, Eh and t °С, phase transitions are formed with subsequent dissolution or precipitation of minerals. To solve these problems, numerical hydrogeomigration modeling is used, including physicochemical, which allows drawing conclusions about the scale of pollution and the localization of such areas for subsequent development of measures to improve the state of the hydrosphere.

Aim. To determine the forms of me-tal migration in groundwater and to calculate water saturation indices in relation to minerals.

Objects. Groundwater in the territory of the closed Levikha copper pyrite mine.

Methods. Laboratory studies of groundwater were carried out using flame emission spectrometry, flame atomic absorption, photometric method with Nessler's reagent, titrimetric, mercumetric and potentiometric methods; mass spectrometry with ionization in inductively coupled plasma and gravimetric method. Physical and chemical modeling using the software product Visual MINTEQ 3.1.

Results. According to the results of processing chemical analyzes and physical and chemical modeling, all tested wells are divided into groups: 1) wells no. 1, 2, 3 and 6, located within the former mining allotment (near the Levikha XIV mine, a man-made reservoir, the Levikha II mine and a neutralization station); 2) represented by water in wells no. 4 near the shaft of the mine Tsentralnaya and no. 5 near the dump Yuzhny; 3) well no. 7, located near the mouth of the Levikha river. Saturation indices and forms of migration of components in the aquatic environment make it possible to identify the scale of pollution and the localization of such areas. Thus, with the current pumping system, there is no large-scale pollution of groundwater at the Levikha mine. It is localized in the area of the Tsentralny mine shaft (well no. 4) and the Yuzhny dump (well no. 5).

Relevance. The permafrost degradation under the effect of global warming. It determines the necessity for a predictive assessment of permafrost stability to minimize disturbances to engineering installations in the permafrost zone.

Aim. To assess the stability of frozen peatlands in the southern part of the zone of insular distribution of permafrost.

Objects. Soils of flat-mound and high-mound palsa mires, which preserve permafrost on the southern border of the insular permafrost zone.

Methods. Measurements of the temperature of peat and mineral soil in geocryological boreholes from 0 to 10 m deep using the SAM-N automatic monitoring surveillance network; determination of surface temperature from thermal channels of MODIS satellite images from 2000 to 2022; analysis of meteorological indices and determination of air temperature trends for predictive assessment of permafrost stability; calculation of indicator values of permafrost state, such as freezing degree-days and thawing degree-days, frost index, freezing and thawing N-factors.

Results. Numerous features of unstable permafrost have been observed. In particular, the mean annual temperature of the surface layer was positive in all studied boreholes (+0.8...+1.3°C), and the temperature at the depth of zero amplitudes (10 m) is close to the melting point (with the predominance of temperatures in the range of –0.2...–0.3°C). Besides, a layer of soil that does not freeze throughout the year (non-merging permafrost) was identified. The thawing degree-days and frost number values correspond to areas with unfrozen soils. Positive trends in air temperature, Earth's surface temperature, and snow depth were observed. For 2000–2022, surface air temperature increased by 0.76°C/10 years on average. The land surface temperature increased in summer by an average of 0.42°C/10 years. If the positive trend in surface air temperatures continues, frozen peatlands in the southern part of the permafrost zone will completely melt in 50–70 years.

Relevance. The need to develop a technology for the disposal of solid and liquid industrial waste to obtain organic-inorganic fertilizer. The growth of industrial production is accompanied by an increase in waste. In modern society, considerable attention is paid to the problem of processing man-made waste to obtain demanded products. Phosphogypsum is the main by-product of the production of fertilizers and phosphoric acid, it is a multi-tonnage waste, its storage leads to the withdrawal of vast territories from circulation. Liquid waste from pig farms also needs to be processed into organic fertilizers.

Aim. To study the process of heat treatment of phosphogypsum in the presence of a reducing agent to obtain an alkalizing reagent. This will make it possible to further organize processing liquid and solid agricultural and industrial waste and produce domestic organic fertilizers

Methods. Heat treatment of phosphogypsum in the presence of a reducing agent, followed by the preparation of an aqueous suspension to obtain an agent that reduces the acidity of livestock effluents. The samples of heat-treated phosphogypsum obtained during the study were characterized by X-ray phase analysis, electron microscopy. Suspensions with different pH values were obtained on their basis.

Results and conclusions. The authors have studied heat treatment of large-tonnage inorganic waste of the chemical industry – phosphogypsum. It was found that the suspension of phosphogypsum heat-treated in the presence of a reducing agent has increased values of the hydrogen index, which can be used to obtain an alkalizing reagent for treating agricultural waste. The authors revealed the optimal technological modes of obtaining a reagent having the maximum pH value of the suspension: the amount of the introduced reducing agent is 0.16 mol/mol CaSO₄, the heat treatment temperature is 1000 °C.

Relevance. When operating submersible equipment for oil production in aggressive environments and transferring wells to the cyclic operation mode, a decrease in the service life of the submersible installation for oil production is observed. In the first case, this is due to the formation of salt deposits and clogging of the working parts of the electric pump with mechanical impurities. In the second case – an increase in the number of starts of the submersible electric motor. To solve the existing problems, it is possible to implement closed control systems for submersible electric motors based on state variable observers, which determines the relevance of the study.

Aim. To develop an observer with operational monitoring of the angular velocity of the rotor and the moment of resistance on the shaft of a submersible asynchronous motor at inconsistency of the initial conditions in various operating modes and its testing using modeling tools.

Methods. The observer is built on the basis of known engine models in a fixed coordinate system α, β, the theory of IIR-filters to obtain a forecast of estimates of the angular velocity of the rotor and the torque on the shaft and their correction in real time.

Results. The authors have proposed the original structure of an observer with operational monitoring of the angular velocity of the rotor and the moment of resistance on the shaft of a submersible asynchronous motor.

Conclusions. The paper demonstrates the observer performance with inconsistency of initial conditions and electric motor model data in various operating modes. In all modes, stable estimates of the speed and torque of resistance on the electric motor shaft are obtained. At the same time, the error in estimating the angular velocity under the condition of changing the load on the shaft and starting in the loaded state is no more than 1.2%, which is acceptable in submersible electric motor control systems. It is revealed that the developed observer, under the condition of changing the active resistance of the stator and rotor in the ranges from –25 to +25% of the nominal value, obtains estimates of the angular velocity with an integral error of no more than 5%, except for starting the motor with a decrease in the active resistance of the rotor by 25% of the nominal value –5.53%, which is acceptable in engineering practice.