Home – Home – Jornals – Journal of Mining Sciences 2022 number 3

The author describes the specifics of the multi-scale mathematical modeling of geomedium as a case-study of a two-scale model. The first scale modeling assumes the linearly elastic medium, and the second scale model includes the plastic strains and internal friction. It is shown that in the first approximation, when the micro-level stress gradients are assumed to be constant, the model acquires elastoplasticity with regard to local bends of structural elements of the geomedium. The solution of the problem on plane S-waves reveals that the waves possess dispersion and their velocity decreases with increasing plastic strains.

The authors develop the DEM-based procedure for the numerical testing of granular samples under non-uniform compression with different load programs. The algorithm of initial packings of particles is proposed. The calculations are performed for different methods of loading with suppressed dilatancy and with dilatancy-generated volume. The macro characteristics of the stress-strain behavior of the test samples are related with the micro properties of discrete particles. The post-critical shearing induces the unstable behavior with localizations of shears, and a descending branch appears in the load diagram. The application ranges of the developed method for the mathematical modeling of shear localization are defined.

The author proposes an eco-friendly method for the remote evaluation of productivity of hydrocarbon reservoirs using records of the natural seismicity background of the Earth. The evaluation uses the thermodynamic indicator of rock mass quality based on the Klimontovich entropy. The latter is a correct measure of disequilibrium of open systems and can be measured from the ratio of chaotic character and orderliness of vibrations generated by the system. The thermodynamic indicator obeys the linear dependence on the total thickness of productive beds in boreholes. The big natural and induced noise may distort the distance evaluation. The new algorithm is high-amplitude noise resistant. The thermodynamic indicator ensures productivity mapping of hydrocarbon reservoirs and enables selecting the most promising drilling sites.

The failure mechanism and acoustic emission are studied in uniaxial loading tests of coal-rock samples at three values of coal/rock ratios. The scope of the analysis includes the stress-time curve, compressive strength, elastic modulus, acoustic emission events and energy counts. The failure characteristics, deformation and acoustic emission of the compound body are analyzed.

In this study, the gauge and phase transition theories are used to develop an elastoplastic model of geomaterials with dissipation. Displacements and plastic distortions are selected as the independent variables. The initial Lagrangian is constructed by the requirement of invariance of the Lagrangian with respect to translational transformation. To take into account the continuous structural phase transition effect of plastic deformation of geomaterials, fourth- and sixth-power terms of the distortion tensor are added to the initial Lagrangian. The differential motion equations of media with dissipation and the corresponding boundary conditions are obtained based on Hamilton’s principle. Generalized Hooke’s laws are obtained on the basis of the kinematic variational principle. One special case, dilatation-compaction deformation case, is discussed, and the obtained equation of motion is applied for modeling the deformation waves and zonal disintegration.

Currently, the rate of heading in mines falls short of the capacities of the advanced power-driven machine systems. High-rate mining technology using a robotic travelling module has no parallel and essentially accelerates operation. Determination of operating modes of the module, their checking and visualization is implemented by combining the simulation modeling and computer animation. The models based on specialized software GPSS Studio and Proof Animation enable interactive studies into joint operation of heading machinery and walking powered roof support. The tests provide the estimate of the heading cycle time.

The authors discuss the influence exerted by the structural features of placers and by the distribution of useful components in them on the efficiency of the resource-saving mining. Considering clustering occurrence of gold ore seams, a geometrization error may reach 100% in some areas of operation. The errors of reserve appraisal are defined, and the applicable approaches to mineral exploration, mining and processing control are discussed. In terms of some placers in Yakutia, it is shown that the main causes of errors in gold reserve appraisal include inaccurate determination of the placer morphology and structure, the width first of all, as well as the gold content.

The article gives methodical guidelines for calculating hourly and daily outputs of bucket chain dredgers. The improved output determination procedure is a chain of calculations of dredger performance in correlation with strength characteristics of rocks and with their depth- and width-varied properties. It is proposed to group the mining time and to take into account the action time losses connected with face cutting, dredging within the placer limits, and with breaks for the auxiliary operations. The delays are included via the introduced face cutting factor. It is found how the technical capacity of dredger, the face cutting factor and the dredger utilization per day change as function of the face width at different thickness of placers. The authors put forward an empirical equation for the technical dredger capacity.

The authors propose a new approach to gravity caving of ore in mining with convergent technologies. Based on the ultimate span determination using the stability graph method by Mathews and Potvin among other things, the optimal conditions of gravity ore caving in block rock mass are defined. Structurally, in the operating layer of an ore body, a vertical cut-out is made, and the inclination angles of walls of the outlining and partition backfill masses are changed. The article presents calculation of the Earth’s gravitation field energy accumulated within the dome of natural equilibrium formed in rock mass in the course of mining.

The authors discuss application of nitrogen-oxygen-sulfur heterocyclic agents as collectors and frothers in flotation of sulfide minerals. Efficient collectors are the compounds which contain nitrogen heteroatom and sulfur atom in pendent group: they can generate complex compounds, including chelate, with copper, antimony and other metals in sulfide ore. Compounds containing sulfur heteroatom can modify sulfide surface, which favors attachment of collectors later on.

A new method of acid leaching of kaolin concentrate is assisted with ultrasound cavitation used as a catalyzing factor. This method allows processing of alumina-bearing concentrate without heating of pulp and vacuum degassing of equipment. The lab-scale tests produced aluminum hydroxide at the yield of more than 90% of theoretical value. The process flow diagram is close-loop regarding all consumables.

The phase transitions of sulfide minerals-pentlandite and chalcopyrite-are tested in roasting with mixture with ammonium sulfate. The behavior of the mixture during roasting is assessed via the synchronous thermal and X-ray phase analyses, and by scanning electron microscopy. The basic optimal technology parameters for the efficient processing of sulfide-bearing copper-nickel ore are selected to be: the roasting temperature of 400 °С, the ore:ammonium sulfate ratio of 1 : 10, the particle size of - 40 µm and the roasting time of 240 min. An important condition is joint milling of ore and ammonium sulfate down to the specified size. Given these parameters, the later on water leaching of clinker provided extraction of 94.8% of copper, 91.5% of nickel and 82.3% of cobalt. The research findings are of essential practical interest owing to the high recovery of the target minerals.

The physicochemical research of ammonium fluoride processing of ash and slag waste is performed as a case-study of ash waste of Blagoveshchensk thermal station and fly ash of Amur experimental technology facility. The optimized conditions are determined for some reactions, including fluorination of feedstock in the temperature range of 50-200 °С, sublimation of ammonium hexafluorosilicate at 350-550 °С, as well as production of amorphous silica, fine-grain alumina, red iron-oxide pigment and calcium fluoride. The basic distribution patterns of rare earths, including Sc and Y, during ammonium fluoride processing are determined. The authors have developed the effective innovation technology for various ash and slag waste processing with extraction of ore microconstituents.

The article offers a review of the existing methods to remove suspended solids from industrial wastewater. The mechanical and physicochemical techniques which are in use already and to be in service in the short term are discussed. It is shown that each specific mine needs its own selection of a package of wastewater treatment methods.

In this study, the synthesis of nickel oxalate was investigated from an extract solution of nickel laterite using precipitation method. The experimention determined the best conditions of nickel oxalate synthesis. To optimize the process, Response Surface Method was applied on the experimental data. The kinetics study of the synthesis process shows that the approach using the Avrami model gives a better approach than the first order integral model. The activation energy generated from the kinetics study with this model is 36.5221 kJ/mol.

The authors propose a novel methodological approach to up-to-date integrated satellite monitoring for studying origination of source zones of natural and induced catastrophes at large-scale subsoil use facilities in Siberia. This approach uses multimodal experimental geomechanical and geodynamic data of Earth remote sensing and digital technologies. This allows orientation at various applied aspects of mining technologies with regard to transition to processing and analysis of Big Data on slow deformation wave processes from the standpoint of nonlinear ‘geomechanical thermodynamics’. The article describes the estimation method for the Earth’s crust surface in Kuzbass Coal Basin using the lineament field analysis and the two-dimensional radar-base satellite data of Earth remote sensing. The use of the geoinformation technology software and testing results are presented as a case-study of a disastrous landslide at a large open pit coal mine in linkage with thermodynamic periods in the geomechanical behavior of the object of monitoring.

Slope fracture detection is critical in the safety management of the open-pit mine, and the non-timely detection of slope fractures may cause landslide or other serious consequences. To prevent the unexpected accidents caused by the failure of slope integrity, this paper proposes an intelligent fracture detection algorithm based on improved Mask R-CNN, which can address the limitations of traditional image processing algorithm and the classical deep learning model directly to the open-pit mine slope crack detection. In this paper, we use the integrated features of Mask R-CNN in target detection, segmentation and location, improve the shortcomings of Mask branch, such as unclear edges and false detections, and construct a detection and segmentation framework for slope fracture images of the open-pit mine. This method introduces dilated convolution neural network, and a classify segmentation iterative up-sampling operation into the mask branch, which can solve the problem of slope fracture Mask’s rough edge. Experimental results show that compared with the traditional crack segmentation algorithm, this method has higher recognition accuracy and better segmentation effect.

Methods proposed for mine water treatment use different advanced equipment such as aerators and circular settling tanks which ensure increase in pH and decrease in impurity concentrations by 10-50 times. Passive mine water treatment uses small cascade ponds, which enables additional purification of water due to deceleration in water flow velocity and because of the longer time of interaction between impurities and reagents. The reconstruction of the existing system of three treatment stages can reduce pollution of surface and ground water, which brings essential improvement of ecology and minimizes damage caused to the hydrosphere.