Home – Home – Jornals – Fundamental and applied issues of mining 2020 number 2

Studies were carried out to determine the causes of periodic fires on the territory of the former sludge sump in Kuzbass. Using various methods for evaluating rock mass and core drilling samples, the causes of exogenous and endogenous fires in different time periods were determined.

The seismic effect of man-induced explosions on underground mine workings of the Magnezitovaya mine was assessed. The seismic stability of rocks in the Magnezitovaya mine was determined and safe distances from man-induced explosions were calculated based on the permissible seismic effect for rocks. To establish the dynamic impact on the workings, the URAN and Minimate Plus seismic recorders with three-component seismic receivers were used. As a result of comparison of the calculated values and the results of experimental measurements, recommendations are given for setting a limit on the mass of explosives in the deceleration stage at the level of minimum dangerous values during man-made explosions in an underground mine.

The article presents an analytical review of the current state of the Russian coal industry and discusses the problem of mathematical modeling and digital technologies in coal quality management and risk reduction.

A calculation method for determining the loss and dilution of ore for a typical variant of sublevel caving with layer-by-layer breaking is given. The results of analytical modeling of ore release for the most representative sublevel height in the practice of underground mining are presented

A new methodological approach is proposed to identify the effect of changing conditions on the performance of drilling operations of a mining enterprise using an open-pit method. Drilling is presented as a subsystem of the more general system called “mining enterprise”, the stability of which is affected by multiple factors. The first stage of implementing the proposed methodological approach to identify the factors of blasthole drilling determining the transition processes as necessary reactions of the “drilling operations” subsystem to adapt for changing conditions is described. The results of revealing the main factors which affect the stability of “drilling operations” subsystem at the level of blastholes at the pilot site of a mining enterprise are presented.

Methods of quarry water disposal at domestic and foreign open-pit mines are considered, and it is found that mining of watered lignite deposits in the Kansk-Achinsk basin using traditional drainage methods is not quite efficient. A technology is proposed for mining a watered lignite deposit without draining it, which makes it possible to reduce unproductive costs for coal production and mitigate the negative effect of open-pit mining on the environment.

The development of drilling and blasting operations at mining enterprises is considered. Drilling and blasting parameters have been developed for explosive breaking of blocks in highly methane-bearing coal seams. It is found that coal combustion after explosions occurred with abundant methane release from 0.25 to 0.37 m³/h.

The article presents the results of experimental studies of a pneumatic impact device, the air distribution system of which has two controlled chambers of compressed air and four valves. This pneumatic impact device has an efficient operating cycle with a reduced specific consumption of compressed air. The operating cycle of a laboratory prototype was investigated and its main operating parameters were determined: frequency and energy of impacts, compressed air consumption. A comparative analysis of experimental results with the results of numerical simulation is carried out.

The results of an experimental study of the influence exerted by the sizes of samples of hornfels, limestone, sandstone, siltstone and ore-bearing rocks on their stress-strain properties are presented. Tests were performed on cylindrical samples of 10, 30, and 100 mm in diameter under uniaxial compression and tension. It is shown that ultimate strength decreases as the sizes of hornfels, limestone, sandstone, and siltstone samples increase. For rocks containing viscous inclusions, there is a slight increase in strength with increasing sample size. The samples of smaller size exhibit brittle failure for all types of rocks, and failure viscosity increases with increasing sample size. An explanation of the obtained patterns of change in stress-strain characteristics depending on rock tendency to viscous or brittle failure, its structural and textural inhomogeneity from the standpoint of two types of scale effect - volumetric and surface, is given.

The effect of a blast on a rock mass complicated with a cavity and tectonic heterogeneity is considered. The heterogeneity is an extended softened rock layer located in the vicinity of the cavity. It is shown that this layer reduces the effectiveness of dynamic effect on the cavity. The dependence of cavity stability during the blast on thickness of the softened layer and strength properties of the rock mass is revealed.

The microstructural analysis of tested coal is performed. The fracture width and sizes of coal micro-blocks along cleats are determined. The laboratory filtration tests are carried out. The coal cleat compressibility and the dependence of coal permeability on hydrostatic stress are determined by the obtained results. The permeability anisotropy along beddings planes is estimated. The predicted dependences of coal permeability along face and butt cleats on occurrence depth are obtained for uniaxial strain conditions.

The paper presents the results of many years of research on the transformation of oil pollution which spreaded to bottom sediments due to oil spill at one of the facilities of the oil and gas complex in the territory of the Sakha Republic (Yakutia). The dynamics of changes in the content of chloroform extracted bitumens for the period from 2007 to 2017 is considered. The features of biodegradation of oil pollution based on the results of studying the chemical composition of bitumens are considered. It is found that in the absence of new oil spills for 11 years, the chemical composition of bitumens changed in the direction of approaching the composition of native organic matter by 2017. The composition is characterized by the presence of compounds typical for higher plant lipids: presence of high-molecular n-alkanes (nC₂₃ - nC₃₃), significant predominance of n-alkanes with an odd number of carbon atoms in the molecule, a high content of oxygen-containing groups and bonds in the chemical structure of bitumens. The performed studies showed that the hydrocarbon state of bottom sediments changed from typical oil pollution at the start of monitoring (2007) to the state typical for natural background (2017).

The article presents options of the implementation of separation processes of high-melting hydrocarbons from petroleum products, which make it possible to simplify the structure, optimize process flow diagrams and improve the quality of oil products.

For the purpose of comparative study of oil source properties of the Devonian deposits in the central part of Kotelny island (New Siberian Islands) and Selennyakhsky uplift (Omulevsky terrain), geochemical studies of the composition, chemical structure of chloroform extracted bitumens of organic matter and relict hydrocarbons were conducted. In terms of the set of bituminological parameters, the studied naphthide occurrences are characterized by large variations in the content of organic matter, the yield of chloroform extracted bitumens, group composition and chemical structure of chloroform extracted bitumens, which indicates the presence of a wide range of bituminous varieties as traces of generation, migration and accumulation of hydrocarbons. According to the composition and distribution features of relict hydrocarbons, the naphthide occurrences in the central part of Kotelny island and Selennyakhsky uplift show great similarity, which is proved by their common type of aquagenic initial organic matter, its high degree of maturity and a sufficiently high generation potential of the Devonian deposits, which entered the zone of the main phase of oil formation and could generate liquid hydrocarbons, and in zones of deeper immersion they reached the main phase of gas formation. The obtained results on the geochemistry of organic matter confirm the existing point of view on the general history of geological development and the similarity of the formation conditions of oil and gas potential in offshore territories of the Laptev and East Siberian seas and the continental part of the East Siberian platform. This allows approaching the assessment of the oil generation potential of organic matter in rocks and the oil and gas content of Devonian deposits on the offshore based on the results of a more studied continental part of the territory in question.

The processes of formation and decomposition of natural gas hydrates of the Srednevilyuiskiy and Otradninskiy gas condensate fields of Yakutia in model solutions of the sodium hydrocarbonate type have been studied. It was found that with an increase in the concentration of solutions, the volumes of gases bound into the hydrate decrease, and the composition of gas affects the decomposition of the obtained hydrates. It is shown that with an increase in the molar mass of natural gas, the rates of hydrate decomposition decrease.

The effect of a hybrid filler consisting of the particles of carbon black and carbon nanotubes (CB/CNT) on the relaxation a-transition, as well as polymer glass transition temperature, which is a measure of the segmental mobility of macromolecules and, respectively, theoretical frost resistance of an elastic material was studied. According to the dynamic mechanical analysis data, the inclusion of CB/CNT hybrid particles in the filler leads to broadening of the temperature dependences peaks of the tangent of mechanical loss TanD for all samples towards lower temperatures and a shift in the position of the TanD maximum by the value from 4 to 16 °С compared to control. The data of differential scanning calorimetry indicate the presence of additional low-temperature α-relaxation transitions in modified vulcanizates (-123 ... -118 ° С). The observed relaxation behavior of macromolecules is caused by the appearance of macromolecules in the material of regions with less dense packing and, as a result, by the expansion of their conformational set during segmental movement at low temperatures. This provides the material with increased fatigue life and frost resistance.

Using patent and information analysis of engineering solutions, the development level of physico-chemical geotechnology of gold heap leaching in the leading gold mining countries is analyzed. Based on the use of advanced information, a comparative quantitative assessment is given to engineering solutions for the objects of invention under two leaching modes - seasonal and year-round.

The article presents the results of a comparative study of the composition and properties of two commercial flotation reagents on an organic basis. It is shown that both reagents exhibit high flotation activity and complex properties of the collector-foaming agent in the process of enrichment of coking coal slurries. It was found that the component composition of reagents is very different, but has similar efficiency. One of them is represented mainly by h - and cycloaliphatic compounds. The second contains aromatic compounds in comparable quantities. The presence of compounds with oxygen-containing polar groups (cyclic alcohols, ketones, aliphatic acid esters) in both reagents gives them the characteristics of complex reagents with heteropolar properties.

The possibility of using natural zeolites in technologies for protecting environmental components during the operation of mining enterprises has been investigated. Issues of complex processing of zeolite-containing rocks have been studied. The most effective technologies for enrichment of zeolites, modification and activation of their properties, as well as purification from enclosing impurities have been determined and substantiated. The main parameters of the application of the proposed technologies for enrichment of zeolite-containing rocks have been established experimentally. The main directions of the use of natural zeolites in order to ensure the comprehensive environmental safety of mining enterprises have been determined.

A brief review of articles on the flotation of minerals using a combination of reagents is presented. It is noted that the main attention of the authors is aimed at studying the effect of the combination of collectors at the mineral-liquid interface. It was shown that one of the reagents or associates formed as a result of their joint action, possessing surface activity, can serve as a desorbed form of sorption and help reduce the induction time during the formation of a flotation complex.

The problems of preserving the performance of pneumopercussion devices while reducing their weight and dimensions for carrying out construction works in a confined space are considered. The results of calculating the dynamics of two variants of percussion devices with two and three pneumatic chambers are presented. It is shown that with the same radial dimensions and threshold impact energy of devices under study, the reserve of increasing the impact power is increasing the impact frequency due to multiple pneumatic chambers.

The procedure for conducting scientific experiments in the development of an automatic flow regulator with hydraulic control is considered. The necessity of using automatic systems in the drilling process is proved. The results of experimental studies of the liquid flow regulator, namely its output characteristic and oscillograms of the hydraulic motor acceleration under various operating modes of the regulator are presented

A schematic diagram of a device for deflecting a hole trajectory during horizontally directed auger drilling is proposed. The problem of deflector interaction with soil under static loading is considered. Using modified Cam Clay model for clay soils of the Ansys finite element package, the parametric problem on determining the dependence of hole axis deflection angle and the value of hole deflection per running meter of its length on the inclination angle of the front plane of rock cutting tool is solved. The optimal value of this angle is calculated.

The problems of creating high-strength composite materials based on ultrahigh-molecular polyethylene reinforced with basalt fiber are considered. In this work, organically modified basalt fiber was used applying a coupling agent and a surfactant. The fiber was introduced into the polymer matrix in concentration of 0.5, 1 and 2 wt. %. The method of scanning electron microscopy revealed an improvement in the interphase interaction between the components of polymer composite material.

The results of calculating air exchange from the piston action of trains in a long railway tunnel by computational aerodynamics methods in a stationary and non-stationary formulation are compared. The errors of determining air exchange in a stationary formulation are revealed. The correctness of applying the models of network static air distribution with quasi-dynamic models of the piston action of trains for calculating tunnel ventilation is justified.

The problems of monitoring physico-mechanical rock properties during drilling as part of the Smart Mine project to build a rational ore flow system are considered. The theoretical foundations of determining the variability of rock physico-mechanical properties during drilling, mainly elasticity, are presented as a parameter characterizing the elastic response of rock to failure. The basic design of the system for implementing the above mechanism with fixing the variability of the elastic reaction of rocks to failure by elastic strain of the drill string and visualization of the obtained data in real time is given.

The features of the schemes of hydraulic impact machines are analyzed. The requirements for hydrostatic machines used in automated drilling systems in the implementation of adaptive engineering processes are formulated. A design of hydraulic impact mechanism with an intermediate drain chamber and annular elastic valve is developed. A simulation model of the proposed hydraulic impact system is constructed and dynamics of the operating cycle is studied.

The operating dynamics of a high-speed borehole seismic source of unbalanced type was studied on a test bench in laboratory conditions. The inner chamber of a vibration source was filled with liquid and the unbalance in it was spun by an electric drive with a rotation frequency from 10 to 50 Hz and a step of 5 Hz. A comparison of vibration amplitudes generated by a vibration source with a dry and a liquid-filled inner chamber is made.

The study of composite properties using the methods of mechanical activation showed the effectiveness of using layered silicates (LS) as PTFE modifiers. The exceptional effect of LS on the increase in wear resistance of PTFE is shown. The most significant influence on the set of PTFE characteristics was determined in the case of filling PTFE with silicates having a dioctahedral grid in their structure, due to the presence of aluminum cations. The formation of a protective layer serving as plastic grease was noted on the friction surface by the SEM method. New sealing materials were developed for extreme operating conditions, they are characterized by increased mechanical characteristics, tribo, frost- and heat resistance.

The proposed technology of polyethylene pipes socket welding can be used in construction of polyethylene pipe systems in mining industry. Based on numerical simulation of thermal process, the effect of low temperatures on the temperature field dynamics in socket weld joint is investigated. The need of preheating and usage of thermal insulation at the cooling stage during welding at low temperatures for the flow of heat process according to the patterns of welding at acceptable temperatures is shown. The procedure for calculating dimensions of heat-insulating chamber for cooling socket weld joint at low temperatures from the condition of ensuring cooling rate inherent to welding at acceptable temperatures is given.

The paper discusses the mathematical model for calculating a nonstationary temperature field in the lip seal of rotary shaft. Finite element method is used to compare mathematical models of thermal process with various assumptions. At the same time, function of frictional heat generation is modeled by set of concentrated heat sources. For a seal of filled fluoroplast-4, the validity of assumption on removing almost all heat released by friction into a steel shaft is shown. Calculations show that for seals operating in low temperature conditions, it is necessary to consider dependence of thermophysical properties of sealing material on temperature. A procedure is proposed for determining the load-speed regimes of polymer seals of rotary shaft according to temperature limiting, considering dependence of thermophysical properties on temperature and heat exchange coefficients on sliding speed.

The work is devoted to the actual problem of welding of polyethylene pipes at low ambient temperatures used in the mining industry. The numerical solution of the thermoelastic problem shows the distinctive features of the thermal and stress-strain states of the welded joint of polyethylene pipes using couplings with a built-in heater at various temperatures of the environment. It is shown that welding in conditions of low temperatures of the environment, the size of the molten zone is substantially less than at permissible temperatures. In this connection, insufficient pressure is created between the coupling and the pipe for high-quality welding. It is also shown that at the time of melt crystallization, the maximum stresses during welding at low temperatures are higher than during welding in the allowable temperature range, which causes high values of residual stresses. The results obtained can be used in the development of welding technology at low temperatures.

The methodology of fractorgaphic analysis of fracture surfaces after tensile testing was developed for ED-20 epoxy based polymer. Fractogrpahic analysis was conducted using roughness and brightness of fracture surface obtained by Confocal Laser Scanning Microscopy. New insight on climatic weathering mechanisms was obtained. The increase in the brittle fracture surface area was observed, which corresponds to the decrease in tensile strength, as the duration of climatic weathering grows.

The laboratory model of a pneumatic hammer with a striker weight of 4 kg and stepwise control of the impact power due to its frequency component is created. Its actual energy characteristics depending on adjustment option are presented. In the experiment, the rod experienced a combined action in the form of periodic shock pulses with an additional static load. Empirical graphical and calculated dependences of the influence of impact frequency and the magnitude of external force on the rate of casing penetration into the soil mass are obtained, provided that the necessary threshold value of pneumatic hammer energy required to overcome the soil resistance is reached.

The design of a domestically produced DTH hammer for drilling holes in rocks of medium and high strength is presented. Using mathematical modeling method, the possibility of hammer operation at an energy carrier pressure of 2.4 MPa is proved. The results of DTH hammer prototypes testing in laboratory conditions and at mining facilities are presented.

An overview of methods for mapping disturbances in a rock mass is given on the example of determining systems of hydraulic fractures in an oil-saturated reservoir. Methods of passive and active microseismic monitoring, as well as electromagnetic methods for examining rock massifs for the presence of inhomogeneities in it are considered. A promising option for the development of hydraulic fracture mapping systems is proposed - the creation of borehole probes, which are a ground penetrating radar that implements the mode of electrical scanning of the studied massif. The calculation of the antenna array of the borehole design based on the Butler matrix is performed. The calculated parameters of a phased array antenna with a Butler matrix can be used to design a downhole probe for mapping hydraulic fractures, as well as to perform a survey of engineering structures, for example, building foundations.