Home – Home – Jornals – Journal of Mining Sciences 2018 number 1

In the framework of the theory of interaction between nonlinear geomechanical and physicochemical processes in coal seams under mining and based on the piston mechanism of gas dynamic processes, it has experimentally been proved that nonlinear quasi-metric elastic pendulum waves from natural and induced earthquakes have influence on gas-dynamics in mines in Kuzbass. The objects selected to identify the interrelationship were the large earthquakes occurred in Kuzbass on November 9, 2016 (magnitudes 2.7 and 3.7) and the records of the quake-induced gas dynamic activity in Alarda and Osinniki Mines.

The actual lithostatic stresses are calculated with regard to physical characteristics and structural features of rock mass. The results are compared with the in-situ observations. It is shown that vertical stresses naturally grow with depth though their values are very different along horizontal cross sections due to the complex structure of rock mass. On the average, the vertical stresses are close in values to the lithostatic stresses. The horizontal stresses measured by the borehole slotter method are many times higher than their calculated values, which is governed by the nonunform properties of rocks or is reflective of tectonic compression.

Stress memory in consolidating composites in acoustic emission is studied experimentally to understand feasibility of its application in stress state control in rock mass. The tests show that, owing to uniformity and comparatively high responsiveness of acoustic emission behavior under straining, composite materials, when placed in a geomedium, allow highly accurate identification of tensor of actual stresses in it.

The classical method to calculate stress state of rock mass disregards the own weight of rocks, i.e. this is a static approach. This article suggests accounting for the own weight of rock mass during formation of a void in it, which is a kinematic approach. In case of similar underground openings differing only is size, the static calculation yields the same stresses below the limiting values, and, theoretically, failure is absent in both cases. The phenomenological theory presented in the article makes it possible to take into account the own weight of rocks in calculations of rock mass deformation around an underground tunnel, and the kinematic supplement shows that, all other conditions being equal, the probability of failure grows with the size of the tunnel.

The data of experimental and analytical studies into the state of development drifts under edges of gently dipping sedimentary sheet-like ore bodies are presented. The stresses in rock mass under the edges of the sheets are determined. The drift state criterion was assumed the ratio of the maximal compressive stresses at boundary of a reference circular cross section tunnel in an elastic medium and at the boundary of the tunnel under the hydrostatic stress field. The results of the instrumental and visual observations in mines as well as the data of equivalent material modeling and analytical solutions agree.

Alternative systems of support for junctures of mine shafts and underground excavations in salt rock mass include monolithic concrete lining, concrete lining with a yielding layer and supplementary reinforcement. It is shown that traditional non-yielding concrete lining needs periodical basic repair every 5-10 years during operating life. An increase in the thickness of such support is not a guarantee of repair-free operation. It is proved to be expedient to support junctures with mine shafts with reinforcement systems of rock bolts or frames with yielding elements. This conclusion is based on the data of instrumental monitoring of adjacent rock mass and on the results of ANSYS-based simulation of evolution of stress state and damaged rock zones in time.

In terms of the complex-structure ferruginous quartzite ore body mining in the Kursk Magnetic Anomaly, the authors validate the requirement to account for anisotropy of rocks with a view to improving performance of preparatory and blasting operations, stabilizing grain size composition, reducing production of oversizes, saving energy input of milling, enhancing useful component extraction into concentrate and decreasing losses with regard to the sound subsoil management conditions. The effect of the first to third order anisotropy on the quality of blasting fragmentation of ferruginous quartzite is analyzed. The theoretical formulas to calculate radius of controlled fragmentation zone as function of geological and geophysical characteristics of rock mass are presented, and the practical results of blasting at open pit mines in the Kursk Magnetic Anomaly area are described.

Water well drilling-with-casing equipment is described in the article. Construction diagrams and field test results of series-production and new drilling-with-casing DTH hammers possessing higher impact energy are analyzed. The economic study of water well drilling cost in geological conditions of the Republic of Altai is performed.

The experimental research of processes running in a linear pulse electromagnetic motor of a downhole vibration generator is described. Based on the research findings, the authors offer design requirements and make recommendations on basic geometrical proportions of the equipment.

The authors formulate and solve the problem connected with the optimization of cutting width of a drum shearer based on the maximum capacity criterion with regard to physical properties and fractional composition of coal. Aimed at calculating drum shearer feed and capacity as function of cutting width, it is proposed to use shearing stress and contortion of beds instead of cutting resistance of rocks. It is found that in order to improve coal sizing and reduce methane release in longwall face, as well as for the uniform distribution of loads on picks, the picks should be arranged on the drum at unequal spacing in accord with the exponential law.

It is found that the slope of access roads influences expansion of nonmining pit walls in order to arrange these roads. Aiming to determine extra expansion of nonmining pit walls, the quick and accurate analytical method is developed. It is proved that the increase of the slope of access roads to the maximum possible values (20-24%) enables reduction in stripping by 20-40 % in deep open pit mines. The mining efficiency in case of steep slopes, aside from extra expansion of nonmining pit walls, is also influenced by the depth of transition to such slopes and the transportation capacity of the access roads depending on distribution of mining operations along the depth of an open pit mine. It is demonstrated that it is most reasonable to gradually increase the slope of access roads with the mining depth, starting from the initial value (8%) and up to the maximum governed by technical requirements and operating conditions.

Application of geotechnology used in high-value quarts mining in Kyshtym Mine is studied. The room-and-pillar method is trialed, and the actual mining performance is evaluated. The potential benefits of the geotechnology are evaluated. The air-decoupled charges without inert filler are designed and tested for fan pattern blasting. Size distribution of broken ore is estimated, and optimal parameters of blasting and powder factor are determined. The feasibility of quartz loss reduction to 3 times owing to extraction of useful mineral from pillars and due to decreased yield of overground quartz by 25-40% is proved.

The method of dynamic loading of sucker-rod pumps to act upon the producing well bottom zone is described. The effect is exerted through the underpump sucker-rod joint set on the well bottom. Under the weight of the flow string, the underpump sucker-rod joint loses pitch stability and is pressed to the inner surface of casing pipes. The operating sucker-rod pump induces axial vibration in the string, which generates lateral stresses transmitted to the adjacent rock mass along the spiral contact line between the underpump sucker-rod joint and the casing pipes. This dynamic impact on inactive or slightly active interlayers invokes fluid flow in them and results in enhanced production of wells. The field test data are presented to illustrate the described effect in wells in different geological conditions.

The main objective of mine ventilation network optimization studies is to develop a reasonable method for ventilation system control that minimizes the total cost of mine ventilation. The fundamental principles for ventilation network optimization are discussed, and a multi-objective optimization model is established from the viewpoint of total cost. Furthermore, an optimization algorithm based on the airflow asymptotic calculation is presented by the hierarchical analysis of objective functions and analysis of the structure characteristics of a ventilation network. In the proposed approach, the regulated branches are determined by the directed path matrix; the optimal solution is obtained by airflow asymptotic calculation using the existing software for ventilation network analysis, and it does not need to solve the large-scale nonlinear programming problem. The results of example analysis validated the reliability of this approach.

Coal mine ventilation is an extremely complicated system that can be disturbed by several factors. This report addresses the fact that the stabilization of airflow in the airways can be induced by gas ventilation pressure. The formation and characteristics of gas ventilation pressure are further elaborated and combined with the airflow stagnation accident that occurred in the Tangshan coal mine in China. Field tests, numerical simulations and experimental studies were conducted to verify the role of gas ventilation pressure on the stability of airway airflow. The results indicate that gas ventilation pressure is generated in inclined airways with gas accumulation, which can be regarded as an increment of natural ventilation pressure. Gas ventilation pressure can induce airflow stagnation or airflow reversals, especially in airways with relatively low airflow velocity. To maintain the stability of the airflow, mine ventilation structures must be strictly managed to ensure a higher airflow rate and velocity in those airways with gas emissions and avoid arranging airways with large dips.

Using ultraviolet-visible spectrophotometry and laser and electron microscopy, adsorption of cyanuric triamide agent (CTA) at the surface of silver-rich galena PbS-Ag and pyrite FeS2-Ag is recorded. The X-ray spectrum of the new reagent phase on silver particles contains O, C and N bands typical of CTA. New experimental data on kinetics of selective flocculation of ultrafine particles of silver-bearing sulphide minerals under treatment by CTA and thermally degraded polymers (TDP) are obtained. It is found that CTA and TDP introduced jointly in sulphide slime pulp accelerate settling of slime fractions, which promotes mineral aggregation and improves flotation performance. The prospects of using CTA and TDP as modifiers in flocculation of slime fractions of silver-bearing minerals are demonstrated.

The material composition and process properties of hematite-braunite iron-manganese ore from South Khingan deposit of Russia’s Far East are studied. The source of manganese in the ore is mostly braunite. The mineralogy and petrography of the ore and its processing products are characterized. Noble minerals are found in the ore; the composition of gold contains platinum and silver admixtures. Producibility of manganese concentrates with the Mn content of 37.85-46.46% using the circuit of multi-stage combination of magnetic separation in weak and strong field and, then, concentration by gravity is experimentally proved.

The process of leaching oxidized nickel ore in sulphuric acid with the additives of sodium sulfite and fluoride is investigated. Tochilnogorsky deposit ore (Sverdlovsk Region) is used to prove theoretically and experimentally efficient application of fluoride in dissociation of nickel minerals (nontronite and garnierite) in oxidized nickel ore. It is shown that at NaF consumption of 10 kg/t, it is possible to enhance maximum extraction of nickel to solution from 82.3-86.9 to 96.0-98.7% at the residual sulphuric acid concentration of 10-20 g/l in the working bath. It is found that the sodium fluoride additives lower the process activation energy from 22.8 to 12.9 kJ/mole. This means that the reaction of sulphuric-acid leaching proceeds in diffusion-kinetic mode and that sodium fluoride is applicable as the leaching accelerator.

The current technologies available in the world market for the chemical processing of caustobioliths of carbonic series are overviewed. The prospects for the expansion of the coal supply base in the Far East of Russia are discussed, and the main lines of advancement in the coal preparation industry are specified. It is possible to arrange coal chemistry clusters in the Amur Region (thermal conversion of coal, production of Montana wax and oxidized humite), in the Khabarovsk Territory (in-situ gasification) and in the Primorye (motor fuel and liquid fuel production).

The constructed economic-and-geological model of a commercial alunite deposit in the Amur Region (in terms of Burinda mineralization) includes two scenarios based on the criteria of alumina requirements in and development profitability. The production infrastructure involves open pit mining and processing based on reduction and alkaline treatment in a unified circuit with synnyrite. The calculations show that construction of a mining and processing plant at the deposit is profitable in both scenarios.

The economic and ecological recommendations on integrated and efficient management are made for Dashkesan Mine in the north-east of the Small Caucasus and for sulphide-complex ore deposits on the South Slope of the Big Caucasus with a view to applying modern methods and resource-saving technologies in extraction of basic metals and alloy elements, management of mining waste, dust and gases, reducing production cost and environmental protection.

As a component of multi-functional safety control, the man-machine mine shaft alarm system ensures safe conveyance of personnel and cargo in mines. The designed interfaces, circuits and architectures, hot backup and the objective-coordinated communication protocols guarantee strict orderliness, reliability and safety of control.