Home – Home – Jornals – Journal of Mining Sciences 2025 number 2

The authors performed a series of DEM-based numerical experiments connected with complex loading of a granular medium with continuous rotation of the principal axes of strains. The question of a trace of delay in the scalar and vector properties in the medium by Ilyushin is discussed. On the authority of the dilatancy analysis, the delay trace is calculated for the scalar properties of the granular medium. The delay in the vector properties is found in terms of the change in the directions of the principal axes of stresses, strains and strain rates during loading. The quantitative evaluations are given. It is found that the delay trace in granular media is one-two orders of magnitude higher than in metals.

The methodology to determine physical and mechanical properties of granular materials containing coal is substantiated. A set of methods and facilities is developed to find bulk density, cohesion coefficient, internal and external friction coefficients and distributive capacity for ROM coals, coal concentrates and other coal-bearing materials. The laws of change in the listed characteristics within some variation intervals of process parameters are found for the real-life processes of coal flow and storage. The integrated studies and systematization of coal flow process parameters are described.

Selection of efficient methods and means for rock fracture is one of the major challenges the coal mining industry is faced with. For rocks of high hardness, the most efficient fracture method is drilling with button bits. The main objective of the implemented research is determining the actual time of contact between bit buttons and rock and the required time of contact to reach the destructive load with respect to various influences.

The authors analyze the mechanical and process properties of gabbro, diorite, peridotite, serpentine and talc carbonate rocks of the Bazhenov chrysotile asbestos deposit. The hardness metering is performed on the surface of the sampled hand specimens. Their compression and tension strengths are found in the air-dry condition. The interrelations are revealed between the mechanical properties of the test rocks and the hardness meter readings. Using an empirical relationship, the crushability classes of the test rocks are determined. The correlation is found between the hardness meter readings and rock crushability at the test deposit. Finally, it is inferred that the present-day idea of the rock strength-crushability connection is valid both in traditional and express method testing.

Experiments on dried and saturated marble samples were conducted at different loading rates to investigate the influences of loading rate and saturated water on the deformation, strength and brittleness indexes of marble. Strength and deformation, the applicability and variation of different brittleness indexes, and the relationship between elastic strain energy limit and brittleness indexes were analyzed comprehensively under different loading rates. The results show that the strength of marble increases with an increase in loading rate, while elastic modulus decreases and peak strain increases. The influence of loading rate on brittleness was analyzed for seven values of the latter. The results indicate that some of the indexes of brittleness cannot reflect the influence of loading rate. Meanwhile, there are two indexes that can accurately express the variation law of rock brittleness with an increase in loading rate. Moreover, these brittleness indexes increase linearly with an increase in loading rate and exhibit a quadratic function relationship with elastic strain energy limit. A new brittleness index that can comprehensively consider strength and energy is proposed to fully express the effects of loading rate and saturation on rock brittleness. In accordance with the macroscopic failure characteristics of marble, the conclusion that a brittleness index increases with an increase in loading rate was proven correct.

The article addresses peculiarities of solid mineral mining in difficult geological and hydrogeological conditions in eastern Russia. The known methods of preparing wet deposits for their further mining are reviewed. Special attention is given to mineral extraction from deposits in river channels, which is the most expensive process subjected to difficult-to-accomplish ecological requirements. The wet deposits are grouped with respect to possible drainage and opencast mining technologies. Some eco-oriented mining technologies are put forward, with efficient management of natural and manmade resources.

A correlation is found between the pressure pulse amplitude of the power unit of a vibration exciter and the impact energy of the driving piston of an electromagnetic percussion drive as a component of the exciter. The correlation is used to investigate energy characteristics of the electromagnetic drive. It is shown that the energy contributed by the flyback coil to the total mechanical work done by the electromagnetic drive in one cycle is 70-75%, while the energy contributed by the forward run coil is 25-30%.

The authors present a practical problem solving scheme for the prediction and control of mining machine condition using real data from sensors tracking basic parameters of open pit mine trucks. The network analysis of signals from 15 sensors is performed for two systems of Komatsu HD1500-8 dump truck: internal combustion engine and gear shift transmission. The network nodes are selected to be the time series data on one operation shift of the machine. Connections between the time series were found on the basis of similarity of temporal sequences. The similarity between temporal sequences was estimated using the Dynamic Time Warping (DTW). The networks were constructed using a threshold model, with a threshold set as the time-series similarity. It is found that some networks respond to a machine failure on the day of its occasion, the day before and the day after it. The results prove applicability of the network analysis for the timely detection of mining machine failures.

The article focuses on the upward potential of efficiency in vibropercussion driving of steel structural tubing shapes in soil by means of improvement of interaction between the components of the air-driven hammer-pipe-soil system. The preproduction model of a generator with the stepped adjustment of the movement intensity of the traveler member via transition to the increased pressure of an energy source is described. The experimental modeling data on penetration process are reported as function of loading of a pipe string by the equipment with different kinetic parameters-mass and piston-anvil co-impact velocity. It is determined how these parameters influence amplitudes of generated power pulses and the resultant advance of a pipe per unit impact in the elastoplastic soil mass.

The article describes the observation data on temperature at a place of spontaneous combustion at a waste dumps via holes drilled to a depth of 2.5 m. The 4 years-long measurements made it possible to determine the temperature change patterns in coal-bearing waste in the surface layer, as well as at the depths of 0.5, 1.5 and 2.5 m depending on seasonal variations in air temperature. The temperature grows with depths in all holes. For this reason, at the hole length of 2.5 m, the efforts to size the source of spontaneous combustion depthward the waste dump failed. Within the observation period, the maximal temperature of rocks at the source was 500 °С.

The authors analyze the influence exerted by content of common salt in pore space in frozen ground on moisture migration processes. The scope of the analysis encompasses three types of ground (clay, chalk and clayey sand) typical of freezing depth in shaft sinking at potash mines. It is found that the increase in salinity decreases intensity of frost heaving, except for a zone of small concentrations (to 0.0035 kg of salt per 1 kg of dry mineral). The total mass of salt transported to the freezing front grows nonlinearly with the increase in the initial salinity. The obtained results are theoretically interpreted using Darcy’s law for moisture migration rate, and the convective diffusion equation for salinity. It is shown that the key parameter to define the non-monotonous behavior of moisture migration toward the freeze front is the relative hydraulic permeability of ground, which in a complex manner depends on salinity.

The mechanism of change in the acid-base properties of quartz and the structural changes of magnetite surface under the action of low-temperature air-dielectric barrier discharge plasma were experimentally investigated under standard conditions with a view to enhancing extraction of quarts in froth product of reverse cation flotation, and to refining quality of magnetite concentrate. Improvement of electron-donor properties of quartz surface governed the increased adsorption and flotation activity of the mineral relative to cation reagents. The effective parameters of diffuse barrier discharge and the time of plasma pretreatment of mineral samples are determined. As a result, the recovery of quartz in froth product grew by 8-10% and the yield of magnetite was no more than 5%. The modifying effect of the low-temperature atmospheric-air plasma improved the quality of magnetite concentrate at Mikhailovsky GOK from 68.91 to 70.34% owing to the increased recovery of quartz in the froth product of reverse flotation by 3.20%.

The article describes the research aimed at improvement of pretreatment and processing technologies as a case-study of refractory complex ore with regard to specifics of its mineral composition. The ore features a fine-grained structure, with numerous micro-interpositions and close intergrowth of ore minerals. Crystals of sphalerite, which is the main mineral of the test ore, has emulsion-type dissemination of chalcopyrite and other sulphides: galena, pyrite. The use of X-ray radiometric separation as a method of ore pretreatment is investigated.

Separation facilities ensuring flexible control over produced ore mass quality, with potential production of concentrates with high metal content are examined. The process solutions are justified to develop small gold ore deposits located far from processing factories, in the areas of the underdeveloped or missing energy infrastructure. A mobile processing facility carries out two-stage X-ray radiometric separation of sorted ore classes, with production of tailings, middlings and concentrate via float-and-sink separation. Middlings are treated on-the-spot by heap and trench leaching, and concentrate is shipped to a long-distance processing factory. Separate processing of different-grade mineral raw material enables high metal recovery at a reasonable cost.

In order to separate fine-grained monazite minerals from other heavy minerals and silicate gangue minerals, this article discusses flotation studies carried out at various flotation process parameters, such as reagent doses, pulp pH, conditioning time and flotation time. Surface response techniques and experiments were used in optimization research. The best flotation performance conditions are determined to be as follows: pulp pH-9, pulp density-30%, depressant sodium silicate-1.2 kg/t, collector oleic acid-1.2 kg/t, conditioning time-5 min and flotation time-10 min. A single stage yields a monazite grade of 94.8% and a recovery of 95.3% from a feed comprising 52.3% monazite, based on the experimental parameters mentioned above and the expected values determined via response surface methods. Cerium monazite, which is appropriate for recovering rare earth elements, is present in this sample.

Quartz raw materials for the foundry and glass industries, which must have an appropriate satisfying chemical and particle size composition, according to the standards and special requirements of users, are produced at quartz sand separation plant in Serbia. The process of quartz sands preparation in a separation plant is simple and includes the following stages: screening, washing, classification and attrition. In practice, depending on market requirements, different types of sand from different deposits are processed. In addition, the sands in the deposits are heterogeneous and differ, most often, in the content of clay to be separated, so in many cases it is difficult to satisfy the requirements of consumers. One of the reasons is the lack of automatization, where changes in process flowsheet lead to a stop of process, which entails difficulties in operation and stoppage of this process unit. Taking in the account the above, in order to implement optimal automated control and monitoring of the process, industrial tests were carried out on a separation plant. The tests were carried out on a hydrocyclone of the first stage of classification (as the most important unit of this process), equipped with appropriate control and measuring devices (CMD) to perform this task, namely: a frequency regulator of the pump electric motor and a manometer for measuring the pressure at the feed inlet of the hydrocyclone. In order to evaluate the classification process of various quartz sands in a hydrocyclone, the classification efficiency was determined using partition numbers and a partition curve, and taking into account the parameters of the sharpness of separation. The obtained results of industrial tests have confirmed that as a result of changing the feed pressures of the hydrocyclone, while controlling other technological parameters of the process, it is possible to successfully treat raw quartz sands from various deposits and obtain a product with satisfactory characteristics, especially in regard to particle size distribution. In addition, the results are encouraging in relation to future implementation of automatic process control and appropriate monitoring.

This study aims to assess and predict blast-induced ground vibrations of opencast coal mine. The analysis was carried out using two methods i.e. the widely employed empirical vibration predictor known as the USBM (United States Bureau of Mines) equation, and a machine learning model called the artificial neural network (ANN). A dataset including 38 blast vibration recordings was collected and used for the development of an ANN model. Additionally, these datasets were employed to evaluate the site determination constants of the empirical vibration predictor. A total of 27 recordings of blast-induced ground vibrations were gathered from the same opencast coal mine in order to assess the effectiveness of both models. The output (dependent variable) for both models is the peak particle velocity. The effectiveness of the prediction model was evaluated by using commonly used statistical measures, namely the coefficient of determination (R²). Consequently, the ANN model that was built exhibited more precision in comparison to the existing empirical model. The ANN model exhibited a strong positive relationship between the observed and anticipated peak particle velocity values, as shown by the coefficient of determination (R² = 0.84).