Gornye nauki i tekhnologii = Mining Science and Technology (Russia)

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Vol 7, No 1 (2022)
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5-17 461
One of the most problematic aspects of underground block leaching (UBL) of metals from ores is the possibility of pollution of water and air in the affected zone. Therefore, proving the possibility of mitigating environmental impact of metal leaching from ores by managing production processes with the implementation of nature- and resource-saving technologies is an important objective. The purpose of this study is to justify underground development effectiveness of ore deposits by traditional and integrated methods with leaching of metals from substandard and off-balance ores. This will allow the raw material base for extraction of metals from off-balance ores to be expanded and the environmental impact on subsoil and groundwater (hydrogeological systems) to be mitigated. A distinctive feature of a UBL (underground site for leaching of metals from shrunk ores) is that leaching solutions are supplied from sorption column placed in mining workings of the leaching level in the immediate vicinity of the extracting block. The pregnant solutions in the form of resin are discharged from the sorption column, placed in the leaching level mine workings, then winded in mine cars and further supplied to hydrometallurgical plant in tanks. A still rare attempt to justify the efficiency and environmental safety of underground metal leaching (UBL) from off-balance and substandard rock ores in installations mounted in mine workings, on the basis of monitoring and evaluation of subsoil and groundwater conditions was investigated. The average value of uranium concentration by level was established: 210 m – 3.6 mg/L; 225 m – 3.58 mg/L; 280 m – 0.91 mg/L. At the same time no contamination of underground mine waters was detected. Levels of sulfuric acid aerosols and radon decomposition products did not exceed the maximum allowable concentration (MAC) values. It is recommended that the hydrogeological environment be protected through silting the bottom of the stope for collection of pregnant solutions with clay mud and construct semi-active water-permeable chemically active barriers. The mentioned BIL process was implemented during the development of pilot block 5-86 and recommended for blocks 5-84-86 and 5-88-90 of Michurinskoye deposit of SE VostGOK, Ukraine, as well as during for development of ore deposits in Russia, Kazakhstan, and other developed mining countries.


18-29 213
Geological features are characterized by macro- and micro-heterogeneity, manifested by the spatial variability of material composition and lithophysical properties of rocks. This, in turn, determines the spatial and temporal variability of hydrocarbon (HC) fluid dynamics both during the reservoir formation and during its development and, subsequent operation as an underground gas storage facility (UGSF). The long-term operation of underground gas reservoirs at the Galmas and Garadagh areas in the South Caspian Basin (SCB), serving as a reservoir of commercial gas accumulations, and subsequent underground gas storage (UGSF) is characterized by significant peculiarities. Analysis of monitoring data on volumes of gas injection and extraction at the Galmas/Garadagh UGSF in the period of 2020–2021 showed their spatial variability, as well as the variability of wells deliverability during the gas reservoir development. This suggests the inherited nature of UGSF operation mode in relation to the gas reservoir development mode. The heterogeneous nature of spatial variability of these parameters is determined by the reservoir rock poroperm properties. A formation pressure drop during reservoir development is accompanied by decreasing rock permeability. When operating UGSF, the lithofacial properties of rocks determine the ratio of volumes of injected and extracted gas. In this regard, a necessary condition for selecting the optimal system of UGSF operation is to take into account the spatial heterogeneity of the underground reservoir. The irregular nature of variation of rock poroperm properties, the origination of isolated zones in the reservoir with considerable residual gas volumes, as well as unpredictable directions of fluid movement are the main reasons for decreased efficiency of field development and underground gas storage facility operation. In order to determine the optimal system of operation of UGSF in depleted underground oil and gas reservoirs, the features of the spacial variations resulting from the rocks poroperm properties need to be taken into account.


30-36 248
In the area of solid state physics and materials science, new knowledge has been attained in recent years about micro-nano-plasticity using high-precision measurements at low stresses and strain. Rock microplasticity is currently poorly understood, but in the future it may prove useful in resolving problems of a fundamental and applied nature. This study examines the effect of cyclically varying pulse amplitude and wave velocity on the attenuation parameters of longitudinal wave (P-wave) in sandstone. Laboratory measurements were performed on rock specimens using the reflected wave method in the frequency range of 0.5–1.4 MHz at five values of strain amplitude ~ (0.5-2.0)10–6. Trial simulations were performed, in order to establish the effect of amplitude-dependent wave velocity on the parameters of wave attenuation in the sandstone. Wave attenuation behavior under combined action of the amplitude-dependent factor and wave velocity deviation is complex. The change in strain amplitude shifts the attenuation peak 1/Qp(f) in the attenuation-frequency coordinates. The maximum change in peak attenuation value due to the amplitude factor and wave velocity deviation reaches 3–4 %. An open wave attenuation hysteresis loop was identified as a consequence of the closed amplitude cycle A1(+) --- A1(+) --- A1(–), where A1(+) = A1(–). Open attenuation hysteresis occurs both in the cases of constant and variable wave velocities. The length of the open part of the attenuation hysteresis loop relative to the peak value of the attenuation is as follows: for constant wave speed, 62.63 %, in the mode of increasing wave speed, 91.58 %; and, in the mode of decreasing wave speed, 47.01 %. The effect of open hysteresis of wave attenuation in sandstone can be explained by the action of microplastic deformation detected in the experiments.


37-48 352
With limited mineral resources, existing mines are seeking to extract increasingly hard-to-reach and deep-seated mineral reserves. Increasing mining depth leads to problems connected with the provision of comfortable and safe working conditions. The main objective of creating favorable microclimate for miners is to provide acceptable values of air temperature in working areas at deep levels. Of particular interest are processes of formation of thermal conditions in longwall faces (longwalls), where high-performance hauling and mining equipment is used. We conducted a study to determine the formation of the thermal conditions in longwall faces. The study was based on experimental data obtained in the conditions of longwall face No. 1 of the first northern panel at the –440 m level of 4 RU mine of JSC “Belaruskali”. The findings of the experimental study of the dynamic microclimatic air parameters allowed us to establish that the thermal conditions in longwall faces were variable. This is due to the fact that during mining operations in longwall faces, the mining process cycle includes mining and maintenance shifts, characterized by different levels of heat release. The influence of thermal inertia of the equipment during shutdown for the maintenance shift plays an important role in the formation of thermal conditions. The findings of the experimental study of transient thermal modes in a longwall face during transition from mining shifts to maintenance shifts will form a basis for developing a mathematical model to calculate the heat exchange processes in mine workings (longwall faces). These will take into account the non-stationary nature of the technogenic heat release sources. The mathematical model will allow the safest and most effective technical and economic process solutions to be implemented, in order to control longwall face ventilation.


49-56 418
Tunneling in urban conditions requires costly measures, in order to ensure the safety of existing buildings. On average, there are up to 17–20 buildings per 1 km of Moscow Subway Lines under construction. Analysis and comparison of geotechnical monitoring data and results of geotechnical estimations for underground construction using cut-and-cover and tunneling methods in conditions of high-density urban area shows an unsatisfactory correlation between estimated and actual data. This can be described in the following way: insufficient geotechnical survey data; discrepancy between the accepted estimation model and the actual behavior of soil under load; insufficient qualification of the construction workers; and overcutting. The study was aimed at solving the urgent scientific and engineering problem of determining the characteristics of overcutting during mechanized tunnel boring. At the first stage, the investigations were aimed at identifying the key reasons and factors which determine the quantitative parameters of overcutting in urban underground construction by tunneling. These factors include the following: mismatch between the cutting diameter and the outer lining diameter; displacement of the soil mass in front of the face; incomplete grouting of voids beyond the lining; incomplete filling of beyond-shield voids with clay mortar or slow-curing grouting mortar or no filling at all; and human factor (low qualifications of personnel). The overcutting coefficient was determined on the basis of the proposed empirical dependence of its values with regard to the depth of tunneling. The experimental data allowed the depth dependence of the overcutting coefficient for different tunneling depths to be defined, as well as for tunnel diameters from 4 to 10 meters in the case of mechanized tunnel boring machine (TBM) using the earth pressure balanced tunneling method. The practical importance of the studies consists in determining the range of the empirical overcutting coefficient variation from 0.5 % (for TBMs with nominal diameter of 10 m) up to 5 % (for TBMs with nominal diameter of 4 m). The development of organizational measures and justification of process solutions, aimed at ensuring the safety of the existing buildings in conjunction with the scientific and technical support of underground construction has led to a shortening of tunneling time between the Okskaya and Nizhegorodskaya stations of Nekrasovskaya Line of Moscow Subway by about six months. It has also provided savings of about 2.5 billion rubles.


57-65 388
This paper presents the results of the development of automatic control systems for walking dragline excavator digging process. The process enables operational productivity to be enhanced through optimizing digging process. This also prevents extreme loads on machinery and hoist cable deflection. The paper also describes mathematical models of the electric drives of the main excavator machinery which form the bucket motion and the model of cable length change. Further the study will analyse the tructure of the control system and the automatic digging algorithm. Computer modeling findings are also described to confirm the operability of the automatic digging algorithm. Computer simulation of the processes in electric drives of main machinery of a walking dragline in digging operations was performed by means of SimInTech software. The automatic control system optimizes digging trajectory with very fast penetration with permissible overregulation following digging at a constant cut depth. The integrated system of dragline operation process control is practically independent due to the following factors: the automatic digging control system in combination with automatic systems for transporting the loaded bucket to dump and the empty bucket to the face; the automatic main machinery overload protection systems; and the system of control over safe bucket movement in the dragline working space.
66-77 264
One of the main factors for the effective functioning of the power supply system in highly productive coal mines is the uninterrupted power supply of underground consumers for the entire process cycle at sufficient amount of electric energy at a high level of quality and performance. The analysis of electric energy consumption in highly productive coal mine has shown that about 57 % of electric energy consumers are located in underground workings. Consumers can be divided into the following areas of basic technological process of coal production: production areas (13 %); conveyor transport areas (13 %); preparation areas (8 %), and areas of auxiliary processes of coal production: mine drainage (23 %). The increase in the share of controlled-velocity electric drives in the total power balance of fully-mechanized longwalls leads to factors previously atypical of underground power networks. Such factors include changes to the harmonic composition of the network, arising higher current and voltage harmonics, affecting the supplying network and causing heating of electrical equipment, power and electric energy losses. Therefore, the most pressing issues are to improve electric energy quality in underground electric networks of highly productive coal mines. The study has developed a technique for experimental investigations of quality indicators of electric energy (presented in the form of algorithm) in respect to specific conditions of highly productive coal mines. These include dangerous facilities in terms of sudden gas/dust outbursts. This technique was tested at a number of coal mines of JSC SUEK-Kuzbass. The study also presents the results of experimental investigations to determine the actual level of total harmonic distortion (factor) in underground electric networks of fully-mechanized longwalls of coal mines. Of greater importance is justification of higher harmonic filter parameters. To this end a calculation algorithm based on the developed technique has been proposed. Research has shown that application of forward and inverse Clarke transformations for calculating the harmonic filter parameters is applicable for all voltage levels. The simulation model of power supply system of a coal mine fully-mechanized longwall allows conditions of higher harmonics damping to be studied by means of a device for improvement of electric energy quality. Applying the proposed technical solutions to improve the quality of electric energy based on the simulation modeling allowed the successful damping of higher harmonics to be achieved. For example, the total harmonic components voltage (THD (U)) was reduced from 9.07 to 1.77 %.
78-88 296
The efficient consumption of electric power in mining is an important task in power consumption optimization. The use of high-performance drilling rigs requires special attention to the development of energy-saving electric drive for open-cut mining operations. The increase of the efficiency factor and energy performance of a drilling rig is achieved through controlling the electric drive which allows the specific resonance frequency and limiting the current and velocity amplitudes to be regulated. The main idea of the study lies in the application of fuzzy controllers in the systems of automatic control of processes and equipment modes in mining production. The use of fuzzy controllers is aimed at improving the characteristics of PI and PID controllers. The calculations and simulation of transients based on simulation models in the MatLab 7.11 Simulink software package allowed reliable analysis of modes of a swivel head electric drive operation to be carried out. In the course of simulating the transients of swivel head velocity varying with the use of a fuzzy controller, fuzzy variables including mismatch of rotation velocity, mismatch change speed, velocity setting voltage were justified. The analysis allowed for the term-sets of fuzzy variables and the membership functions for each term-set of fuzzy variable to be defined. The simulation results showed that the control time (response) of transients of the swivel head motor torque and current change when using the swivel head velocity control by a fuzzy controller with increasing load depending on the rock hardness decreased by a factor of 2. Implementation of a system of automatic control of swivel head velocity with the application of a fuzzy controller allows drilling rig vibration to be reduced and provided effective protection of the swivel head electric (motor) drive from overload, thus increasing reliability of the equipment, and increasing drilling productivity.

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ISSN 2500-0632 (Online)