Home – Home – Jornals – Journal of Mining Sciences 2021 number 5

The article presents the integrated research into geomechanics and geodynamics of Small Tulukui uranium ore field in southeastern Transbaikalia. The studies into tectonic structure and the terrain morphometry in the area of the Steltsov ore field reveals the modern geodynamics features and their correlation with the stress-strain behavior of rock mass. The stress field parameters and the physical/mechanical properties of rocks point at potential of dynamic fracture in the edge area of the deposit. The numerical stress-strain modeling and in-situ observation data prove the tendency of rock mass to rockbursting, and the bottom levels of the deposit (at the depth of 500 m and downward) are assessed as rockburst-hazardous. A package of measures aimed to prevent rock bursts and to reduce geodynamic risk is developed for the mining safety.

The authors describe the dilatancy testing of granular media composed on similar spherical particles-glass balls, millet grains and peas. The testing included simple shearing and complex loading with continuous rotation of the strain tensor axes. The cyclic deformation enables partial elimination of defects of the initial stochastic packing and promotes its transition to a reversible state. The optimal relative density of a packing is presented for the discrete element analyses.

The authors discuss the numerical and field research findings on seismic radiation of water flow in a fracture. The flow parameters can be remotely controlled using the amplitude-versus-frequency response of the vibrations recorded. It is recommended to include the infra-low frequency control in the seismic monitoring in hydrodynamically hazardous mines.

3D discrete-element modeling is used to analyze passive pressure applied by dense soil to a retaining wall. The soil particles have spherical shapes with the radii selected from the normal distribution. The calculation of tangential forces between the particles takes into account the sliding friction and rolling resistance. The surface roughness of the retaining wall has influence on localization of shear strains in the granular medium and on the pressure applied to the wall by the granular material. The calculation results are compared with the classical solution of the limit state theory.

The damage to the surrounding rock under the adjacent explosive load generally manifests as fracture growth. In order to in-depth understand the fracture growth law and mechanism, fracture growth process in the surrounding rock with a nearby adjacent tunnel under the explosive load is studied using the dynamic caustics method. Test results indicate that the original fracture growth process can be divided into two stages, demarcated when the main fracture penetrates the original fracture. The original fracture grows in the vertical direction due to the free surface of the tunnel in the first stage. The main fracture from the explosive source plays a dominant role in the growth direction of the original fracture in the second stage, and the original fracture deflects and grows parallel to the main fracture. Based on kinematic and energy analysis, the penetration process is companied by energy transfer and superposition. The neglected back-facing side also contains fracture on the lower side. The fracture growth direction changes after the original fracture penetrates the free surface of tunnel under the combined effect of the original fracture and unloading wave.

The authors asses water hazard and select methods to prevent it in the areas that are saturated with water and subjected to intensive drainage in the Upper Silesian Coal Basin. The research is important in the areas adjacent to the mines that are closed owing to flooding of roadways and hence is significant for the assessment of the influence of secondary saturation of the rock mass with water on the rock mass mined in an active mine. Changes to the occurrence conditions of the geodynamic phenomena of rock bursts are discussed in the context of the processes of restructuring mines and the associated processes of water inflow and flooding closed mines. The propensity of the rock mass to rock bursts in the border areas between active and closed mines is assessed.

The rational mine support system designs for underground excavations in backfill are discussed. The current mine support technology applied in excavations in backfill in Artemievsk and Orlovsky mines is examined. The strength and deformation characteristics of backfill samples are tested on a laboratory scale. The FEM-based stress-strain analysis of ore body and backfill is described with the assessment of their stability. The probable failure zones in backfill and ore body during to-downward slice mining are determined. The rational support design is validated for backfill having stability category I, II and III. The pilot test data on the load-bearing capacity of friction-anchored rock bolts in backfill are assessed. The economic efficiency of the mixed-type support composed of steel frame and friction-anchored rock bolts in backfill is demonstrated.

The article proposes an integrated approach to safety evaluation in underground mining of rare, noble and nonferrous metals. The approach includes joint assessment of variable rock properties, zoning of mineral deposits and ranking of the integrity criterion of natural arch span. The authors validate geotechnical stability in sublevel stoping as a case-study of the Shokpak-Kamyshovoe deposit. The feasibility of mining of isolated and thin bodies without backfilling or with induced caving of enclosing rocks is determined.

Depletion of available mineral resources in the metallurgy industry, as well as the growing internal and external demand for the high-quality iron products necessitates development of new iron ore fields in Siberia. This article offers description of climate, geology and hydrology in the area of the Bakchar oolitic ironstone deposit in the Tomsk Region as a promising subsoil use object. The literature and engineering solutions on this matter are reviewed. The mining risks in the conditions of high environmental standards and market uncertainty are described. The basic requirements are formulated for the potential geotechnologies, and the conceptual framework is proposed for the environmentally sound and resource-saving mining with smart usage of natural and manmade resources in the iron ore production cycle.

Safety of open pit mining in complicated geological conditions can be improved using the multilevel geomechanical monitoring of pitwall and adjacent rock mass. The domestic and foreign practices of pitwall stability monitoring are reviewed. The proposed approach need the operating mines to be equipped with advanced control equipment, procedures and services in order to jointly expand essentially the geomechanical monitoring possibilities.

The recommendations are given for conical pick patterns to prevent growing forces on neighbor picks of a failed pick. It is proposed to detect promptly pick failures by analyzing the burden variation in the transmission system of the cutting head. According to the theoretical calculations, when a pick fails, the relative growth of the feed force is not higher than the relative growth of the cutting force as against the increase in the burden as a consequence of change in the cut rock strength. This hypothesis was tested and proved during shafting at Talitsky site of the Upper Kama Potash-Magnesium Ore Deposit using shaft cutting machine 1SPKV-8.0.

The integrated thermodynamic calculations and spectral analyses validated concentrations of hydrophobization agents (butyl xanthate and sodium oleate) to ensure chemisorption and chemical interaction with silicate matrix of luminophore FL-530. It is found that in the optimized conditions, hydrophobization agents interact with zinc orthosilicate without volume reaction which degrades spectral characteristics of luminophore. The increased oil receptivity of luminophore FL-530 improves its ability to remain in the organic phase of emulsion and to better attach to the surface of diamonds. The UV visiometrics revealed better attachment of hydrophobic luminophore at diamonds. The optimal concentrations of solutions of butyl xanthate and sodium oleate are determined. The tests using separator Polyus-M proved efficiency of hydrophobic luminophore FL-530 which essentially enlarged amplitudes of the fast and slow signal components in X-ray fluorescence of slight florescent diamond and their recovery in separation.

The article describes the studies into sulphide extraction from ore using an integration of flotation and oxidized copper leaching in the conditions of milling with nonacid complexing agent-ammonium sulfate, and adsorption-electrolytic recovery of copper from pregnant highly mineralized copper-bearing solutions. The thermodynamic function of products of interaction of between the base copper minerals and the yield of the hydrolysis ammonium sulfate solutions. The mechanism of sulfate ammonium leaching of oxidized copper minerals in joint mechanical-thermal activation treatment is proposed. The tests on treatment of low-grade complex copper-bearing ore from stockpiles by combination of chemical and electrochemical methods and on the mixed-type flotation-hydrometallurgical processing technology of complex copper-bearing ore were carried out.

This paper aims to encapsulate the trends in the variation of speed with real-time parameters, i.e., temperature and the corresponding change in humidity thereof for the underground mine ventilation system. The purpose mentioned above is fulfilled using a precise and vigorous estimation method of the speed for the sensorless induction motor drive (IMD). The developed model reference adaptive scheme (MRAS) speed estimator can be utilized to control the IM speed for the underground mine ventilation system based on the real-time parameters. The present work is on temperature and humidity-dependent MRAS based sensorless speed estimation technique for IM used in mine ventilation drives. This methodology has been tested analytically and experimentally using MATLAB/Simulink and LabVIEW-2013 laboratory interfaces. Furthermore, a statistically validated empirical relation between the temperature, humidity of the underground mine and speed of the ventilation system has also been developed to facilitate calculations of the same. However, implementing the proposed methodology in an actual underground mine remains a thing of the future.

The air flow dynamics in a vertical mine shaft under conditions of mixed convection is theoretically studied using 3D modeling in ANSYS. The average heat-transfer coefficients are obtained at the air-lining interface depending on air-lining temperature difference and on the average air flow velocity. The threshold velocities of air flow are determined at various air-lining temperature differences. At the air flow velocities higher than the threshold, the engineering designs can neglect the influence of the heat-gravitational forces and use the formula of heat transfer in induced convection. When the air velocity is lower than the threshold, the heat-transfer coefficient should be adjusted with respects to the natural convection effect. The authors offer an empirical formula for calculating the average dimensionless heat transfer coefficient in case of prevailing natural convection.

Hot and humid mine atmosphere can produce a strain on the human body. The study of water vapor in air is known as psychrometry and psychrometric properties of mine air allows to calculate the heat and moisture content. The psychrometric conditions of mine air have a great effect on the health, safety and productivity of employees. When considering the climatic conditions of a mine, the high temperature and humidity problem must be considered. Thus, it is possible to find out the heat and moisture content of air by making psychrometric calculations. In this study, measurement studies have been carried out to determine the increase of heat and humidity in a coal mine using mechanized production method in Turkey and then, heat and moisture exchanges in mine air were calculated. At the end of the study, according to EN ISO 7243: 2017, the amount of required air flow to provide the acceptable climatic conditions was calculated.

The aim of the research is to propose that artificial neural networks be applied in the process of identification of structurally altered coal. The results suggest that the proposed methodology of classification, due to its high effectiveness exceeding 90% of correct identifications, may be successfully used as a tool supporting the observer's decisions concerning the description of coal from near-fault zones.