Home – Home – Jornals – Journal of Mining Sciences 2023 number 6

The article describes the development stages of an adequate regulatory structure for the slope stability in open pit mines. Some supplementary factors that have influence on stability of slopes in open pit mines in the gravity-tectonic stress field are discussed. The main trends of research of pitwall rock mass in operating surface mines are presented, and the necessity of determining the tectonic stresses in pitwall rock mass and taking into account their impact on slope stability is emphasized. The algorithm is developed for justifying slope parameters for open pit mines under tectonic stresses, the drilling-and-blasting principles are formulated for the operation in pitwall rock mass, and the methods are proposed to mitigate the blasting-induced impact on adjacent rocks.

The Ground Penetrating Radar method is used to study a three-layered model of the surrounding rock-void-lining interface with regard to variation in the void thickness and in the electromagnetic properties of the void filler. The numerical modeling uses the method of finite differences in the time domain. The numerical modeling data are compared with the results of the physical simulation implemented using SIR-3000 GPR with the Model 52600 antenna having the working frequency of 2.6 GHz (S-band). It is found that the size of the void behind concrete lining and the electromagnetic properties of a material filling the void have influence on the accuracy of ranging to the lower boundary of the void and to the discontinuity in the form of a steel bolt located immediately behind the void in surrounding rock mass.

The article addresses the problem on thermal stresses and stress-strain behavior of rock mass during deep-level mining. The author proposes an approach to determining the stationary field of temperatures in the zone of mining with cemented paste backfill with single formation of stiffness matrix in the calculation. It is found that inclusion of the temperature change depthward rock mass in the analysis results in the increase in the initial horizontal stresses while the initial vertical stresses remain unaltered. The calculation method of stress redistribution in the course of mining with backfill, with the same stiffness matrix used at all calculation stages, is modified for taking into account the thermal stresses. The calculation of the thermal stress state of surrounding rocks and backfill is carried out for a variant of mining with backfill in a gently dipping ore body.

The mathematical modeling of creep and long-term strength of rocks uses the non-associated flow rule. The authors propose a unified approach to the plasticity and creep processes. The theoretical calculations are compared with the testing data of different materials. In creep deformation in rocks, the applied problems on limit state of rock mass in plain strain are considered: pressure applied by a solid die block with flat bottom on rock mass limited by a horizontal plane and occupying the bottom part of a half-space; instability of pit wall or natural slope under different loads. These problems evaluate stresses in the limit state zones and the times-to-failure in rocks mass with regard to internal friction.

The article discusses tectonic stresses determined in the West Sakhalin terrain using different tectonophysical methods. The reconstruction of the stress field in coal fields in Sakhalin is implemented using the graphical method of orientation finding of stress axes in fractures and faults (at 16 observation points). The supplementary on-site tectonophysical studies made it possible to estimate the preferred orientation of the main slickensides of different kinematics and to reconstruct on this basis the local stress tensors at 53 observation points. The typical stress state of the West Sakhalin terrain is horizontal tension.

The features of mining of a coal series are described. The stress-strain behavior of rock mass during mining of the lower strata in the series is assessed with regard to the influence of coal pillars and upper level roadways. Different variants of location of a temporary roadway on the lower stratum in a series protected by a pillar are discussed. The implemented prediction of the stress-strain behavior of rock mass is adapted to the conditions of mines in the south of Kuzbass. This prediction is used to select the geomechanically safest variant of location of the temporary roadway.

The article describes the studies on permeability of coal cores with a through drainage fracture with and without a monolayer of a proppant. The experimental procedure is descried. The parameters of the jointed structure of test long-flame coal are given. The efficiency of wedging drainage fractures by a sparse proppant monolayer in building up permeability of deep-seated coal is demonstrated.

The article describes determination of oxidizability and spontaneous combustion of ore and rocks as a case-study of the Oktyabrsky deposit. The rate of oxidation of sulfide ore increases after watering. The authors present the studies on sensitivity of ore and enclosing rocks to spontaneous combustion, as well as on gas emission in isothermal conditions and in heating. It is found that sulfide ore, hornfels and gabbro-dolerite are sensitive to spontaneous combustion.

The authors provide the theoretical and experimental justification for the effective methods of modification of saponite-pillaring and thermal treatment-which ensure production of sorbents possessing high cation exchange capacity relative to cations of heavy metals. The mechanism of pillaring and thermal modification of a saponite-containing product at the temperature of 625 °С involves expansion of layers of the mineral, formation of additional acid or redox sites (pillaring) and restructuring with generation of metastable phases (thermal treatment). Modification of saponite increases static exchange capacity relative to copper cations by 2 times after pillaring and by 2.6 times after thermal treatment.

The main mechanisms of flotation activation by ions of metals are discussed and critically analyzed. It is shown that ions of metals can be both activators and depressants of flotation. Based on the mechanism of physisorption, it is revealed when metals act as activators and depressants. A method is proposed to stimulate selectivity of extraction of a target mineral in case of undesirable activation of flotation of associate components. The studies can be useful in selection of metal-activator, ratio of concentrations of activator and collector and pH of flotation system.

The article presents evaluation of preparability of iron ore from Yakovlevo deposit, Kursk Magnetic Anomaly, using magnetic, gravity and X-ray radiometric methods of coarse particle separation. The detailed study involved a material with particle size of - 100 + 25 mm, containing 25-45% Fe_total and 3-35% of Fe_magn and requiring dressing. It is found that effective separation of the initial feedstock into ore and dirt is ensured by the X-ray radiometric method of separation of coarse particles - 50 + 25 mm in size. At the analytical parameter equal to 2, the increase in the content of Fe_total in the ore product reaches 1.18 times at the loss of 5.52%.

The author investigated the modes of thermal and heat-and-radiation treatment of ferruginous bauxite from Vezhayu-Vorykva deposit and revealed different mechanisms of mineral transformations. Under thermal treatment, oxo-hydroxides transform into anhydrous iron and aluminum oxides, while under heat-and-radiation treatment, scattered microelements form metal alloys and new minerals. It is recommended to ground ferruginous bauxite processing on basic science, first of all, nanomineralogy, and on phenomenon of phase heterogenization. This approach can promote an increase in recovery of fine particles of aluminum and other valuable components from low-grade bauxite and red mud by eco-friendly techniques.

The article describes the experimental studies on the recovery of chromite ore obtained from the Askale-Kop deposit (Erzurum/Turkey) using a laboratory-type KC-MD3 Knelson concentrator. For this purpose, the parameters of pulp feed rate, fluidization water flow rate, pulp solids ratio, bowl speed and particle size were examined as variables in the experimental studies. As a result of the experiments, the maximum Cr₂O₃ grade was obtained at 54.68% in chromite concentrate at fluidization water flow rate of 12 l/min, pulp feed rate of 1.5 l/min, pulp solids ratio of 20% and bowl speed of 800 rpm. The highest concentrate recovery value (76.85%) was obtained at fluidization water flow rate of 6 l/min, pulp feed rate of 1.5 l/min, pulp solids ratio of 20% and bowl speed of 1080 rpm.

The flotation process and magnetic separation are the most common methods for feldspar beneficiation containing approximately 0.4% Fe₂O₃ and 0.04% TiO₂. A model MIH (13) 111-5 Induced Roll dry high-intensity magnetic separator was used in this investigation to produce high-quality feldspar concentrate, and investigate the effects of magnetic field strength and roll speed on reducing coloring minerals. The best results were obtained at a magnetic field intensity of 16600 Gauss and a roller speed of 24 rpm. A feldspar concentrate containing 0.16% Fe₂O₃, 0.01% TiO₂ and 10.31% alkali minerals (K₂O + Na₂O) was obtained with a mass recovery of approximately 69.24%. As a result, the products that met the white glaze and ceramic requirements were produced.

The mixed explosive-and-reagent effect exerted on a cemented mineral mass, which simulated an ore body, by explosive charges arranged in reagent solutions was investigated. Pretreatment of the model material by explosive injection of different reagent systems leads to pre-oxidation of copper contained in the material, which stimulates its subsequent leaching. The maximal increment in copper recovery in pregnant solution reached 83% relative to the check value. For the pre-oxidation of copper contained in the model material, the mixed explosive-and-reagent treatment used: electrically activated solution sodium bicarbonate and peroxide, mixture of sodium hydroxide and peroxide, sodium hypochlorite and distilled water. The complexing agent in copper leaching was agent Jin Chan in standard and activated states. It is found that activation of solutions using electrochemically treated sodium bicarbonate before adding the complexing agent enables higher effective recovery of copper from model materials after mixed explosive-and-reagent injection preparation.

The optical polarization method with ring-shaped photoelastic sensors, digital photography of isochromatic patterns and their clarification using neural networks is developed for the stress measurement in rock mass. The case-studies of the photoelasticity application in solving various problems of elasticity and rock pressure analysis are reviewed. As a result of a lab-scale experiment, a data set of 15 000 isochromatic images is collected. The machine learning algorithm was a convolutional neural network, the Inception module. The authors recommend using downhole sensors for the continuous stress monitoring in underground mines and integrating the obtained data in a digital model with the help of IoT.

The authors propose a sequence of acquisition and interpretation of geospatial data obtained using different methods and means during mineral mining toward the accuracy increase in evaluation of industrially disturbed land. This approach uses the concept of stage-wise transition from the areas of industrial facilities to their individual points. The integration of data of satellite surveys, ground-based laser scanning and unmanned aerial surveillance in the digital models of land areas is described. It is highlighted that the rational combination of different methods of geospatial data acquisition and interpretation produces a high-accurate geoinformation system of digital twins of various subsoil use facilities.

The features and trends of coal mining in the east of Russia are examined. The current and planned managerial decisions connected with coal production and supplies to competitive markets are analyzed. The coal products are ROM fuel, concentrate and middlings. The authors discuss approaches to effective mining and processing management within the chains of supplies, and to provision of the required quality of solid fuel produced and delivered to customers.

The present study analyzes the fatal accident occurrences of seventy years from 1951 to 2020 in Indian coal mines. The autoregressive integrated moving average (ARIMA) model, Brown’s double exponential smoothing method, Holt’s double exponential smoothing method, and neural network time series forecasting are used in this research to analyze fatal accidents and forecast future accident incidents. By analyzing various parameters of the applied models, the neural network model was found to be the most appropriate model for the collected data to forecast Indian coal mine accidents as it provides the least root mean squared error (RMSE) (17.62), and mean absolute error (MAE) (13.33) among all models. According to this study, the Neural Network model is the most suitable one to predict Indian coal mine fatality.