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Journal of Mining Sciences

2020 year, number 2

Elastoplastic Model of Rocks under Internal Self-Balancing Stresses. Continuum Approximation

A. F. Revuzhenko, O. A. Mikenina
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: горная порода, упругость, пластичность, самоуравновешенные напряжения, rock, elasticity, plasticity, self-balancing stresses

Abstract >>
The authors construct a continuum approximation for the model of a medium with internal structure and internal self-balancing stresses. The presupposition of diffeomorphism, i.e. existence of partial space derivatives of displacements is largely slackened. The information brought to the closed model of a geomedium by this presupposition is comparable with the information brought by the constitutive equations. The new model includes local bends of grains of the skeleton, plasticity and elastic strains of the binding medium in the pore space. The model is of a gradient type.

Experimental and Theoretical Estimation of Fracture Toughness in Salt Rocks in Testing of Samples with Wedge-Shaped Cut

V. N. Aptukov, S. V. Volegov
Perm State National Research University, Perm, Russia
Keywords: соляные породы, образец с клинообразной выемкой, трещиностойкость, математическое моделирование, salt rocks, sample with wedge-shaped cut, fracture toughness, mathematical modeling

Abstract >>
The article presents the procedure for the experimental and theoretical estimation of fracture toughness in salt rocks in testing of samples with wedge-shaped cut and by numerical modeling of the tests in ANSYS. The values of the stress intensity factor and the energy release intensity factor in tensile fracturing are presented for salt rocks of the Upper Kama Potash Salt Deposit.

Brittle and Quasi-Brittle Fracture of Geomaterials with Circular Hole in Non-Uniform Compression

S. V. Suknev
Chersky Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia
Keywords: хрупкое разрушение, квазихрупкое разрушение, геоматериалы, масштабный эффект, отверстие, градиент напряжений, нелокальные критерии разрушения, brittle fracture, quasi-brittle fracture, geomaterials, size effect, hole, stress gradient, non-local fracture criteria

Abstract >>
The author studies the influence exerted by the boundary conditions and diameter of a circular hole on tensile fracture initiation in brittle and quasi-brittle geomaterials subjected to non-uniform compression with regard to the size effect. The calculation of the critical stress uses the modified non-local and gradient fracture criteria. The calculation results are compared with the experimental data. The developed criteria allow taking into account the size effect when the size of the stress concentration zone is varied by changing both geometry and boundary conditions of the stress raiser.

Methods of Forward Calculation of Ground Subsidence above Mines

K. Ch. Kozhogulov1, D. K. Takhanov2, A. K. Kozhas2, A. Zh. Imashev2, M. Zh. Balpanova2
1Institute of Geomechanics and Subsoil Development, National Academy of Sciences, Kyrgyz Republic, Bishkek, Kyrgyz Republic
2Karaganda State Technical University, Karaganda, Republic of Kazakhstan
Keywords: кривые линий скольжения, паспорт прочности, мульда сдвижения, свод естественного равновесия, коэффициент разрыхления пород, зона деформации, целик, slide curves, failure curve, subsidence trough, natural arch, loosening factor, deformation zone, pillar

Abstract >>
The article discusses geomechanical justification of undermined ground evaluation methods. The proposed method of subsidence assessment allows analyzing influence of underground mining on ground surface in development of horizontal and flat-dipping uniform and interstratified beds with different deformability. The predictive assessment procedures for the subsidence trough profile in case of uniform and interstratified rocks are presented.

Slope Stability in Open Pit Mines in Clayey Rock Mass

N. F. Nizametdinov, R. F. Nizametdinova, A. A. Nagibin, A. R. Estaeva
Karaganda State Technical University, Karaganda, Republic of Kazakhstan
Keywords: глинистые породы, устойчивость, уступ, борт, карьер, угол внутреннего трения, сцепление, кора выветривания, массив, коэффициент запаса устойчивости, clayey rocks, stability, bench, pit wall, open pit mine, internal friction angle, cohesion, crust of weathering, rock mass, stability factor

Abstract >>
Justification of slope parameters for benches and pit walls in clayey rock mass bases on studies into geological structure and physical and mechanical properties of rocks of various lithological varieties. The upper layers of pit walls occur in weak clayey overburden, in the crust of weathering and in transition zone with conglomerates, up to 150 m in total thickness. In this case, it is required to calculate accurately angles of clayey slopes, to undertake cutback at recommended angles and to eliminate heavy flow of melt water and rain water from ground surface to the slopes. Mining within the design pit wall limits should be accompanied by continuous instrumental monitoring of pit wall slopes.

Influence of Stresses and Displacements in Roof Rocks on Roof Fracture in Top Coal Caving

V. E. Mirenkov
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: очистная выработка, пласт, труднообрушаемые кровли, смещения, статика, кинематика, динамика, breakage heading, seam, difficult top coal, displacements, statics, kinematics, dynamics

Abstract >>
The process of roof caving at face during its advance is impossible to describe by static and kinematic solutions. It is necessary to take into account unsymmetry of deformation due to the dynamic component of the roof caving process. To that end, it is required to undertake experimental and theoretical studies into the unsymmetrical displacement distribution. It seems to be possible to obtain additional information on deformation and caving of roof rocks from the elastic solution. The main factors to ensure correct formulation of problems are the statics, kinematics and dynamics of rock mass deformation, and the proposed description of the inelasticity zone in the host rocks-mineable seam system.

Stress Memory in Acoustic Emission of Rock Salt Samples in Cyclic Loading under Variable Temperature Effects

V. L. Shkuratnik1, O. S. Kravchenko1, Yu. L. Filimonov2
1National University of Science and Technology-MISIS, Moscow, 119049 Russia
2Gazprom geotekhnologii, Moscow, Russia
Keywords: каменная соль, напряженно-деформированное состояние, измерения, контроль, акустическая эмиссия, циклическое нагружение, акустико-эмиссионный эффект памяти, rock salt, stress-strain behavior, measurements, control, acoustic emission, cyclic loading, stress memory in acoustic emission

Abstract >>
The behavior of acoustic emission in uniaxial cyclic loading of rock salt samples from the Kaliningrad deposit is determined. The samples were tested under varied temperatures and ratios of maximal stresses in sequential loading cycles. The experimental curves of acoustic emission activity and maximal stress and temperature of the previous cycle are obtained. Stress memory in acoustic emission manifests itself equally stably under constant higher and lower temperatures. Memory of the maximal stress of the previous cycle persists under higher temperature in the next cycle and vanishes under lower temperature in the next cycle. In case of the same maximal stresses and constant or higher temperatures in the successive cycles, the stress memory effect is vague: the stress estimated on this base is lower than the maximal stress of the previous cycle.

Elastic Wave Attenuation Characteristics and Relevance for Rock Microstructures

X. L. Liua, M. S. Hana, X. B. Lia, J. H. Cui, Z. Liua
Central South University, Changsha Hunan, China
Keywords: упругая волна, коэффициент затухания, частотные характеристики затухания, микроструктура горной породы, elastic wave, attenuation coefficient, rock microstructures, frequency attenuation characteristics

Abstract >>
We investigated elastic wave attenuation characteristics using a PCI-2 acoustic emission system. A lead-break test was employed to carry out attenuation experiments in granite, marble, red sandstone, and limestone. Because the centroid frequency variation of the red sandstone differs significantly from the other rocks, a pendulum steel ball impact test was also performed to study the attenuation characteristics of elastic waves in red sandstone. The results show that the elastic wave signal amplitude decreases with increasing propagation distance for all four rock types. In granite and red sandstone, the peak frequency of the elastic wave declines abruptly after the propagation exceeds 800 and 100 mm, respectively, and remains almost unchanged in marble and limestone. The attenuation of centroid frequency in granite, limestone, and marble shows the same trend; however, in red sandstone, when the elastic wave propagation exceeds a certain distance, the variation of centroid frequency shows an upward tendency. The main influence of elastic wave attenuation in rock is the packing state of mineral particles: less tightly packed rocks consistently have a higher attenuation coefficient. The secondary cause of attenuation is the development of structures such as joints and stratifications. More developed interior structures lead to higher attenuation coefficients. Sensor selection is also very important in rock attenuation tests. We recommend use of a wide resonant frequency sensor or sensors with different resonant frequencies along the elastic wave propagation path.

Prediction of In-Situ Cleaved Coal Permeability

T. V. Shilova, L. A. Rybalkin, A. V. Yablokov
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: уголь, кливаж, проницаемость, анизотропия, напряженное состояние, пласт, глубина залегания, coal, cleavage, permeability, anisotropy, stress state, coal seam, occurrence depth

Abstract >>
The procedure is developed for permeability prediction in deep-level fractured coal. Coal permeability and microstructure are experimentally studied on samples taken from the Tikhov Mine. The predictive relationships between the occurrence depth and permeability of coal in parallel to master and side cleavage are obtained for the Nikitinsky, Tambovsky and Tarsminsky fields of the Leninsk geological-economic region in Kuzbass.

Directional Attenuation Relationship for Ground Vibrations Induced by Mine Tremors

P. Banka1, E. Lier2, M. M. Fernandez3, A. Chmiela4, Z. F. Muniz5, A. B. Sanchez3
1Silesian University of Technology, Gliwice, Poland
2FAMUR S.A, Katowice, Poland
3University of Leon, Campus de Vegazana, Spain
4SpГіЕ‚ka Restrukturyzacji KopalЕ„, Bytom, Poland
5University of Oviedo, Campus de Llamaquique, Spain
Keywords: вызванная сейсмическая активность, распространение колебаний на поверхности, анизотропия затухания, induced seismicity, ground vibrations propagation, directional attenuation relationship

Abstract >>
The paper presents the discussion on problems involving the reproduction of the acceleration field of ground vibrations based on the pointwise registration carried out in coal mines subjected to seismic hazard. Simple model that takes into account directional effects of seismic wave attenuation has been presented. It has been accepted the assumption that the contours of the peak ground accelerations take the shape of an ellipse. The carried out calculations for three cases of very strong ground vibrations caused by mine tremors which occurred in three regions of coal mines, show that the application of the proposed model allows us to reduce the value of standard error of the estimate as compared to the results obtained with the commonly applied regression model, which does not allow for the directional effects of attenuation. For the investigated regions, it was showed, that the directional effects of the attenuation depends on the directions of the nearest big tectonic faults.

Enhancing Efficiency of Direct Dumping by Cast Blasting of Overburden Rocks

V. I. Cheskidov, T. A. Tsymbalyuk, A. V. Reznik
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: вскрыша, бестранспортная технология, взрыв на сброс, технологические схемы, взрываемый блок, коэффициент сброса, внутренний отвал, overburden, durect dumping, cast blasting process, flow charts, explosion block, cast factor, internal dump

Abstract >>
The article reports the modelling results on direct dumping of overburden by cast blasting. The cast factor variation as function of seam occurrence and explosion block parameters is found. Potential improvement of cast blasting to displace overburden to mined-out pit area is described. The ways of enhancing efficiency of direct dumping in gently dipping coal extraction by combination of truck-and-shovel system with direct dumping in Kuzbass are identified.

Statistical Analysis of Methane Release in High-Production Coal Faces in Kuzbass

A. A. Ordin1,2,3, A. M. Timoshenko4, D. V. Botvenko4
1Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Institute of Computational Technique, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
3VostNII Science and Production Center, Kemerovo, Russia
4VostNII Science Center, Kemerovo, Russia
Keywords: шахта, угольный пласт, метановыделение, концентрация метана, статистический анализ, допускаемая производительность очистного забоя, газовый фактор, скорость подачи комбайна, выход фракций, mine, coal seam, methane release, methane concentration, statistical analysis, alolowable coal face output, gas criterion, shearer feed velocity, yield of fracions

Abstract >>
The statistical analysis results on methane release in coal faces in Kuzbass are presented. The parabolic curves of methane release have maximums as regard to feed velocity and productivity of shearer. Methane release from broken coal is an inverse proportional function of linear hyperbolic dependence and has maximum as regard to feed velocity and productivity of shearer. The analysis of the found methane release from broken coal shows that methane release reduces as a quadratic dependence with decreasing drum rotation speed and number of picks per cutting line, and increases also as a quadratic dependence with growing thickness of coal seam and shearer web width.

Forward Appraisal of Potential Gold Content of Dredge and Sluice Tailings Dumps at Placers in Russia’s Far East

G. S. Mirzekhanov1, Z. G. Mirzekhanova2
1Institute of Mining, Far East Branch, Russian Academy of Sciences, Khabarovsk, Russia
2Institute of Water and Ecology Problems, Far East Branch, Russian Academy of Sciences, Khabarovsk, Russia
Keywords: россыпные месторождения, гале-эфельные отвалы, потери золота, ресурсы, кондиции, исходное содержание, placer, dredge and sluice tailings dumps, gold loss, resources, quality standards, initial content

Abstract >>
A brief appraisal of probable gold in dredge and sluice tailings dumps at placers in Russia’s Far East is given. In terms of mining waste piles and operating placer mines in the Khabarovsk Territory, Jewish Autonomous Province, Amur and Magadan Regions, a probable gold content of dredge and sluice tailings dumps is predicted. The calculation used different combinations of estimation parameters: loss, initial gold content, fineness of gold sand. It is shown that the probable gold content varies quantitatively and qualitatively as function of combination of the estimation parameters. The tough, optimistic, realistic and unrealistic scenarios of prospects for secondary gold extraction from dredge and sluice tailings are presented.

Analysis of Complexing and Adsorption Properties of Dithiocarbamates Based on Cyclic and Aliphatic Amines for Gold Ore Flotation

T. N. Matveeva, N. K. Gromova, L. B. Lantsova
Academician Melnikov Institute of Comprehensive Exploitation of Mineral Resources, Russian Academy of Sciences, Moscow, Russia
Keywords: горный массив, напряженное состояние, энергия взрыва, gold ore, chalcopyrite, arsenopyrite, flotation, dithiocarbamates, adsorption, complexing

Abstract >>
The authors find that morpholine dithiocarbamate (MDTC) and S-cyanoethyl N, N-diethyl dithiocarbamate (CEDETC) are capable to form stable compounds with gold in the solution and to form an adsorption layer on the surface of gold-bearing sulphides, which points at them as new selective collectors for gold recovery from rebellious ore. The coating area of MDTC on the surface of chalcopyrite, arsenopyrite and pyrite, with new discrete growths is quantitatively assessed. CEDETC improves floatability of chalcopyrite by 1.5-2.0 times as against butyl xanthate at low consumption of reagents, while difference in floatability of chalcopyrite and arsenopyrite considerably grows, which is indicative of a beneficial effect on production of Au-Cu concentrates with lower As content by flotation.

Classification of Low-Grade Copper-Nickel Ore and Mining Waste by Ecological Hazard and Hydrometallurgical Processability

A. V. Svetlov1, P. V. Pripachkin2, V. A. Masloboev1, D. V. Makarov1
1Institute for Problems of Industrial Ecology of the North, Kola Science Center, Russian Academy of Sciences, Apatity, Russia
2Geological Institute, Kola Science Center, Apatity, Russia
Keywords: Арктическая зона Российской Федерации, минерально-сырьевой комплекс, кислотопродуцирующий потенциал, нейтрализующий потенциал, техногенные минеральные образования, сульфидные руды, геотехнологии, Russia’s Arctic zone, mineral mining sector, acidogenic potential, neutralization potential, mining waste, sulphide ore, geotechnologies

Abstract >>
The authors range low-grade copper-nickel ore and mining waste represented by overburden dumps, mill tailings and slag in the territory of the Murmansk Region by the criterion of potential ecological hazard. The determinants of mobility of heavy metals formed in oxidation of sulphides are the content of barren minerals (silicate matrix), pH of pore solutions and exposure to atmospheric weathering (acid rains). The criteria of natural copper-nickel ore and mining waste processability are determined.

Disintegratability Procedure for Geomaterials in Multiple Impact Crushing

A. I. Matveev, E. S. L’vov
Chersky Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences, Yakutsk, Republic of Sakha (Yakutia), Russia
Keywords: дробление, дробилка, обогащение, гранулометрическая характеристика, извлечение, золото, Crushing, crusher, dressing, size distribution, recovery, gold

Abstract >>
The authors justify and exemplify the disintegratability procedure for geomaterials in impact crushing. The procedure distinguishes between two simultaneous processes of destruction and disintegration based on grading analysis of crushing products. The quantitative results on disintegration are obtained for metalliferous geomaterials of different texture and mineral composition. Disintegration is an important process of ore treatment, and disintegratability is an important characteristic of the process and the performance indicator of crushing equipment.

Investigation of Properties of Zinc Plant Residue Mechanically Activated in Two Types of Mills

M. D. Turan1, P. Balaz2
1FД±rat University, ElazД±Дџ, Turkey
2Institute of Geotechnics, Slovak Academy of Sciences, KoЕЎice, Slovakia
Keywords: механическая активация, цинк, кольцевая мельница, высокоскоростная вибрационная шаровая мельница, mechanical activation, zinc, ring mill, high speed vibrating ball mill

Abstract >>
Extended milling/mechanical activation properties of zinc plant residue was investigated using two different milling systems, namely, high speed vibrating ball mill and ring mill, comparatively. The zinc plant residue was mixture of gypsum, anglesite, massicot, quartz, maghemite, and franklinite. Zinc plant residue was milled for 1-30 min in high speed vibrating ball mill and ring mill. The obtained samples were characterized using XRD, SEM, particle size distribution, and N2-BET methods. According to results, it was found that the ring mill caused a further decrease in particle size. Particle size distribution and N2-BET analyses showed that agglomeration of particles began after 15 min and 5 min milling time for HSBVM and ring mill, respectively.

Natural Convection in Watered Rock Mass under Artificial Freezing

M. A. Semin1, L. Yu. Levin1, M. S. Zhelnin2, O. A. Plekhov2
1Mining Institute, Ural Branch, Perm, Russia
2Mehaning Institute, Ural Branch, Perm, Russia
Keywords: искусственное замораживание пород, естественная конвекция, пористая среда, фильтрация подземных вод, математическое моделирование, ледопородное ограждение, artificial freezing of rocks, natural convection, porous medium, ground water seepage, mathematical modeling, frozen wall

Abstract >>
The authors study theoretically the non-isometric natural convection of pore water in rock mass subjected to freezing. The mathematical model is developed for a permeable water-saturated layer of rocks under artificial freezing. The model approximations allowed transition to a two-dimension axially symmetric model. The numerical computation produces critical Rayleigh number values such that natural convection of pore water has a significant influence on temperature and position of phase transition front. Three possible convection regimes of pore water are determined as function of alternating ability of thermal expansion factor.

Open Pit Mining with Blasting: Geoecological Aftermath

V. V. Adushkin, S. P. Solov’ev, A. A. Spivak, V. M. Khazins
Academician Sadovsky Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, Russia
Keywords: микрочастицы в атмосфере, открытые горные работы, массовые промышленные взрывы, численное моделирование, сейсмичность, micro particles in atmosphere, open pit mining, large-scale industrial blasting, numerical modeling, seismicity

Abstract >>
The article analyzes statistics on micro-solid emissions in mineral mining and discusses features of micro-emission in atmosphere in large-scale blasting in open pit mines. The gas-dynamic calculations of dust and gas cloud elevation after blasting for localization of solid micro particles and determination of their concentration in the troposphere are presented. The influence of large-scale blasting on regional seismicity is illustrated in terms of the Kuznetsk Coal Basin.

Hard Coal Production Competitiveness in Poland

J. Dubinski, S. Prusek, M. Turek, J. Wachowicz
Central Mining Institute, Katowice, Poland
Keywords: конкурентоспособность, добыча каменного угля, эксплуатационные затраты, возможности и угрозы, Competitiveness, hard coal mining, exploitation, costs, opportunities and threats

Abstract >>
An analysis of the competitiveness of the Polish hard coal mining sector was performed. The most important conditions in which it operates were presented-the size of the resource base, the current organizational structure, and operating conditions. By presenting the most important sources of competitiveness, factors requiring special attention were identified. After presenting the SWOT analysis of the sector, the issues that were most important for the permanent preservation of the competitive position of the entire sector, as well as individual mining enterprises, were specified.