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Date submitted2022-11-04
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Date accepted2023-03-03
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Date published2023-04-25
Efficiency of acid sulphate soils reclamation in coal mining areas
During the development of coal deposits, acid mine waters flowing to the surface cause the formation of acid sulphate soils. We study the effectiveness of soil reclamation by agrochemical and geochemical methods at the site of acid mine water discharge in the Kizel Coal Basin, carried out in 2005 using alkaline waste from soda production and activated sludge. A technosol with a stable phytocenosis was detected on the reclaimed site, and soddy-podzolic soil buried under the technogenic soil layer with no vegetation on the non-reclaimed site. The buried soddy-podzolic soil retains a strong acid рН concentration Н 2 О = 3. A high content of organic matter (8-1.5 %) is caused by carbonaceous particles; the presence of sulphide minerals reaches a depth of 40 cm. Technosol has a slightly acid pH reaction H 2 O = 5.5, the content of organic matter due to the use of activated sludge is 19-65 %, the presence of sulphide minerals reaches a depth of 20-40 cm. The total iron content in the upper layers of the technosol did not change (190-200 g/kg), the excess over the background reaches 15 times. There is no contamination with heavy metals and trace elements, single elevated concentrations of Li, Se, B and V are found.
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Date submitted2022-04-05
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Date accepted2022-07-21
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Date published2022-11-10
Development of resource-saving technology for excavation of flat-lying coal seams with tight roof rocks (on the example of the Quang Ninh coal basin mines)
- Authors:
- Vladimir P. Zubov
- Le Quang Phuc
It is shown that the creation of the variants of resource-saving systems for the development of long-column mining is one of the main directions for improving the technological schemes for mining operations in the mines of the Kuang Nin coal basin. They provide a reduction in coal losses in the inter-column pillars and the cost of maintaining preliminary workings fixed with anchorage. The implementation of these directions is difficult (and in some cases practically impossible) when tight rocks are lying over the coal seam, prone to significant hovering in the developed space. In the Quang Ninh basin, 9-10 % of the workings are anchored, the operational losses of coal reach 30 % or more; up to 50 % of the workings are re-anchored annually. It is concluded that the real conditions for reducing coal losses and the effective use of anchor support as the main support of reusable preliminary workings are created when implementing the idea put forward at the St. Petersburg Mining University: leaving the coal pillar of increased width between the reused mine working and the developed space and its subsequent development on the same line with the stoping face simultaneously with the reclamation of the reused mine working.
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Date submitted2021-06-15
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Date accepted2021-08-27
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Date published2021-10-21
Prospects for the use of modern technological solutions in the flat-lying coal seams development, taking into account the danger of the formation of the places of its spontaneous combustion
- Authors:
- Vladimir P. Zubov
- Dmitrii D. Golubev
Spontaneous combustion of coal remains an important problem for coal mines, which can lead to an explosion of methane and coal dust. Accidents associated with spontaneous combustion of coal can cause significant economic losses to coal mining companies, as well as entail social damage – injuries and loss of life. Accidents are known at the Kuzbass mines, which occurred as a result of negligent attitude to the danger of spontaneous combustion of coal, the victims of which were dozens of people. The analysis of emergency situations associated with spontaneous combustion of coal shows that the existing wide range of means of preventing endogenous fires does not provide complete safety when working out coal seams prone to spontaneous combustion, therefore, spontaneous combustion places continue to occur in mines. The consequences that may arise as a result of a methane explosion initiated by a self-ignition place indicate the need to improve the used technologies. The purpose of the work is to determine the impact of modern technological solutions used in functioning mines during underground mining of flat-lying coal seams prone to spontaneous combustion, and to develop new solutions that reduce endogenous fire hazard. Conclusions on the influence of leaving coal pillars in the developed space, isolated air removal from the stoping face through the developed space, the length of the stoping face and the excavation pillar, and other factors on the danger of the formation of spontaneous combustion places are presented. Conclusions about the possibility of using modern technological solutions in future are also drawn.
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Date submitted2020-10-26
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Date accepted2021-07-28
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Date published2021-10-21
Investigation of the influence of the geodynamic position of coal-bearing dumps on their endogenous fire hazard
The paper investigates the hypothesis according to which one of the factors influencing the spontaneous combustion of coal-bearing dumps is its geodynamic position, i.e. its location in the geodynamically dangerous zone (GDZ) at the boundary of the Earth crust blocks. This hypothesis is put forward on the basis of scientific ideas about the block structure of the Earth crust and the available statistical data on the location of burning dumps and is studied using computer modeling. A dump located in the area of Eastern Donbass was chosen as the object of research. The simulation results show that the penetration of air into the dump body from the mine through the GDZ, which crosses the mining zone, is possible at an excess pressure of 1000 Pa created by the main ventilation fans. The fire source appearance in the dump body causes an increase in the temperature of the dump mass and becomes a kind of trigger that "turns on" the aerodynamic connection between the dump and the environment, carried out through the GDZ. It is concluded that the establishment of an aerodynamic connection between the mine workings and the dump through the GDZ can be an important factor contributing to the endogenous fire hazard of coal-bearing dumps. The simulation results can be used in the development of projects for monitoring coal-bearing dumps and measures to combat their spontaneous combustion.
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Date submitted2020-05-16
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Date accepted2020-07-30
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Date published2020-12-29
Results of the study of kinetic parameters of spontaneous combustion of coal dust
The article is devoted to the study of the problem of spontaneous combustion of energy grades of coal not only during storage, but also during transportation. As the main samples for the study, the energy grades of SS and Zh coals were selected. The main task of the scientific research was to study the rate of cooling and heating of coal depending on their thermophysical parameters and environmental parameters. To solve this problem, the authors used both the author's installations designed to study the thermophysical parameters of the spontaneous combustion process (the Ya.S.Kiselev method), and the NETZSCH STA 449 F3 Jupiter synchronous thermal analysis device, the NETZSCH Proteus Termal Analysis software package. On the basis of a complex study of the spontaneous combustion process, the authors of the article obtained the kinetic characteristics of the spontaneous heating process (activation energy and pre-exponential multiplier). Nomograms of the permissible size of coal density of different types and shapes of accumulation depending on the ambient temperature are presented, practical recommendations for the prevention (avoidance) of spontaneous combustion of coal fuel are given.
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Date submitted2019-05-26
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Date accepted2019-07-23
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Date published2019-10-23
Ensuring Stability of Undermining Inclined Drainage Holes During Intensive Development of Multiple Gas-Bearing Coal Layers
At high rates of production face advance, requirements towards reliable operation of undermining drainage holes get raised. The issue of maintaining high intensity of gaseous seams development under naturally increasing gas content, mining depth and capacity of production equipment poses a problem. The greatest threat comes from the loss of hole stability in the bearing pressure affected zone (in front of the face) and in the intensive shift area of overhanging rock corbels (behind the face). Intensification of air leaks due to deformation of borehole channel leads to impoverishment of removed methane-air mixture and an increasing risk to disturb safe aerogas regime in the mining area. The paper describes a mechanism of how coal-face operations affect the state of underground holes and formation of overhanging rock corbels. A typification of basic kinds of borehole deformations is presented. Authors point out critical disadvantages of the most widely-used technological schemes of gaseous seams development under high load on the production face, which hinder normal operation of a gas drainage system. As a result of research, a dependency of shot hole number, as well as the distance between shot hole axes and the borehole, on the stress state of the borehole outline has been defined more precisely. Basing on that, a formula to calculate drilling parameters of the discharge hole system has been suggested. Implementation of these measures will allow to increase the efficiency of underground gas drainage and to maintain growing intensity of gaseous coal seam development.
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Date submitted2015-12-22
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Date accepted2016-02-13
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Date published2016-12-23
Risk of injuries among coal mine workers and its hysteresis
- Authors:
- Yu. Parkhanski
The paper gives an overview of employment in coal mining, levels of extraction and injuries among the coal mine operators in Poland over a span of time from 1954 through to 2010. The injury indicators, such as the incidence rate, severity and the generalized loss index, have been assessed for a period of coal mining sector restructuring from 1993 to 2010. Diverging trends have been revealed, resulting in a need to extend the time span of the analysis. Analysis of records from 1954 to 2010 has shown a multiple cyclicity of trends of change in the values used to derive coefficients. The definition of the Injury Risk has been justified, along with a new way for its representation and its interpretation as a new method with account of the previous studies. Based on this method the injuries at the coal mines of Poland during a period of their restructuring have been investigated with analyzed database expansion to include records from 1954 to 2010.As a result a new dependency, namely the injury risk hysteresis, has been identified.
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Date submitted2009-10-12
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Date accepted2009-12-19
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Date published2010-09-22
Preventive measures of gas-dynamic phenomena in the workings drivage on the rockburst- outburst-hazardous seams under extremely complicated geological and mining conditions
- Authors:
- V. P. Kostromin
A complex of measures preventing the manifestation of rockbursts and sudden outbursts of coal and gas has been developed. Criteria of forecasting, an assessment of efficiency of the preventive measures are suggested, as well as the necessary technical facilities and technologies.
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Date submitted2009-10-05
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Date accepted2009-12-05
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Date published2010-09-22
Control of rock mass state in mining the sections at mines оf the Vorkutaugol JST: up-to-date practice
- Authors:
- O. V. Yamenko
- I. E. Plisko
The article briefly outlines the methods and measures used at mines of the Vorkutaugol JSC to control the stress strain state of rock massif. These measures help to increase face load and to ensure mine safety.
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Date submitted1950-08-24
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Date accepted1950-10-14
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Date published1951-08-08
Materials for the qualitative characteristics of coal in the Nelidovsky district
- Authors:
- I. G. Kuprov
The properties of coal in the Nelidovsky district are generally characterized in exploration reports based on the results of petrographic and chemical analyses of core samples. The exploration materials indicate that humus coal varieties (duren, clarene-duren and claren) are predominantly common in the Nelidovsky district, while humus-sapropel varieties are less common. The analyses provided in the same materials show a clearly expressed inconstancy of the chemical composition of coal. Thus, its technical composition is characterized by the following data: hygroscopic humidity from 2.85 to 33.74%; ash content of dry coal from 28.41 to 46.63%; volatile yield on a dry basis from 21.21 to 33.03%; total sulfur from 1.16 to 2.30%. The elemental composition of the organic matter is as follows: carbon from 68.05 dog 75.42%; hydrogen from 4.42 to 5.70%; nitrogen from 0.33 to 1.30% and oxygen in total with sulfur from 20.93 to 26.33%. The yield of dry distillation products: moisture from 3.90 to 15.60%; resins from 3.50 to 9.00%; semi-coke from 63.26 to 83.60%; gas and losses from 6.80 to 12.20%. The calorific value of dry coal fluctuates within 3470-5269 calories. Obviously, the main reason for the inconsistency of chemical properties is the petrographic heterogeneity of coal. Therefore, to resolve the issue of the most rational use of coal in this newly developed region, it is important to know what role each of the petrographic types plays in the formation of the layers and their properties.