Coal Strip Mine Research Articles

Effect of super-high water materials backfilling on stress decrease and energy release during strip coal pillar mining: A case study

Mining strip coal pillars left due to strip mining is important to resource-exhausted coal mines in eastern China. Backfilling mining is an effective means to mine strip coal pillars, which could decrease high stress and high energy release. However, materials with super-high water content were not widely applied in deeply isolated coal pillar mining due to lower strength characteristics and durability. In the paper, taking panel c8301 as engineering background, theoretical analysis, numerical simulation, and field monitoring were used to study the feasibility and application effect of the super-high-water backfilling technology in deep isolated coal pillar mining. The results showed that: (1) Panel c8301 is a strip-filling working face with insufficient mining on both sides, and the mining of the panel will trigger the rebalancing of the overlying rock structure on both sides, which increases the rock burst risk. (2) Simulation results indicate that the super-high-water filling method, in comparison to the traditional caving method, significantly reduces peak stress and elastic energy from 112.3 MPa to 4.6 × 106 J to 79.2 MPa and 2.23 × 106 J, respectively. This represents reductions of 29.6 % and 51.5 %, effectively mitigating the impact of mining activities on overburden movement. (3) On-site measurement data confirmed that the measured equivalent mining height was 1.25 m. The total number of microseisms and the amount of released energy decreased significantly, More specifically, three big energy release instances (>1.8 × 105 J) were recorded during the first roof weighting stage and panel in square meters. Super-high-water filling technology has achieved remarkable results in the mining of strip coal pillars and has significant application prospects.

Повышение ресурса рабочих колес центробежных насосов шахтного водоотлива

Mining The article discusses the main failure causes of centrifugal pumps used in the mine dewatering plants. The factors causing intensive wear of the impellers used in centrifugal pumps of the CNS-33-66...330 type are analysed, as well as the ways of increasing their serviceability. The gas dynamic cold spraying is recognized as the most promising and efficient method of applying functional coatings, which makes it possible to improve the condition of the surface layer and eliminate surface defects of the initial impeller blanks, which have a significant impact on the serviceability of the parts. The main research trends are outlined in the studied area, and practical recommendations are provided on using the gas dynamic cold spraying methid both in the pump manufacturing process and in their overhaul. It is shown that one of the promising trends in development the gas dynamic cold spraying applications is the creation of multilayer coatings on the impeller blades based on compositions of various metal-ceramic powders. Along with the hardening treatment, this combination will allow to provide the impellers with a set of necessary functional characteristics for the hydro-abrasive wear conditions. technological process as a sequence of changing the natural state of the Earth's subsoil to obtain a certain quantity and quality of mineral products is characterized by departures from the specified normative parameter values, which is due to causes of different nature. Most of these causes are man-made, anf they are created during the performance of specific process operations by the personnel. The article presents an original approach to managing the control over the technological process parameters in a coal strip mine. To reduce the magnitude and probability of the process departures from the normative values, the authors propose to create technical and organizational control loops. Each loop is a closed chain of technical means and organizational tools, which secures up-keeping of the normative technological process state. Production risk is proposed to be used as a criterion to assess the efficiency of the control loops. The methodology allowing to calculate the risk is described. The results of the contour approach application to the technological process control at the Solntsevsky coal strip mine are presented.

Формирование контуров контроля технологического процесса угольного разреза

Mining technological process as a sequence of changing the natural state of the Earth's subsoil to obtain a certain quantity and quality of mineral products is characterized by departures from the specified normative parameter values, which is due to causes of different nature. Most of these causes are man-made, anf they are created during the performance of specific process operations by the personnel. The article presents an original approach to managing the control over the technological process parameters in a coal strip mine. To reduce the magnitude and probability of the process departures from the normative values, the authors propose to create technical and organizational control loops. Each loop is a closed chain of technical means and organizational tools, which secures up-keeping of the normative technological process state. Production risk is proposed to be used as a criterion to assess the efficiency of the control loops. The methodology allowing to calculate the risk is described. The results of the contour approach application to the technological process control at the Solntsevsky coal strip mine are presented.

Оценка трещиноватости отрабатываемого горного массива на основе аэрофотосъемки и методов машинного зрения

The task to assess rock mass jointing are currently usually solved in manual mode, which requires high qualification of the specialists and considerable time expenditures. Automation of such tasks is important in terms of reducing the time of image processing and obtaining additional information on the geomechanical state of the rock mass. The article discusses the possibilities of using computer vision and artificial intelligence technologies to assess jointing of the rock mass. For this purpose, aerial photography data obtained using unmanned aerial vehicles are used. The images are processed with the software developed by the authors, which performs tracing of the joints based on a neural network of a dedicated architecture. The results of processing aerial photography data are presented using the cases of coal strip mines in Kuzbass and open-pit mines of the Kola Peninsula. The use of neural network in processing of the aerial survey data of the rock masses has shown the promising potential of the method. After processing the data of tracing the jointing fields, it becomes possible to monitor the behavior of the rock mass by using the visualization tools for additional fields of characteristics, which allow to assess the nature of changes occurring under anthropogenic loads. The developed algorithms make it possible to significantly accelerate the processes of aerial survey data processing to assess the structural disturbance of the rock mass.

Оценка направлений использования техногенных ресурсов при отработке различных видов минерального сырья

The paper reviews the issues related to closure of the Korkinsky coal mine in the Chelyabinsk Region. The authors describe the directions to utilize such man-made resources as open-pit excavation, overburden, and tailings generated during mining of coal and newly developed copper ore deposits. An assessment of possible ways to use man-made resources is provided in relation to abandonment of the worked-out Korkinsky coal mine. Backfilling with copper ore dressing tailings has been justified as the most rational way to abandon the worked-out coal strip mine. The paper describes the process of the backfill material production and its transportation to the discharge point. Backfilling of the Korkinsky coal mine with backfill material will help to solve environmental and social challenges of the region.

Volumetric Structure of the Bachat Earthquake (Kuzbass) Aftershock Area and Stress State of Rock Mass under Open-Pit Mine

Abstract —The Bachat earthquake (M = 6.1) with the epicenter coordinates of 54.29° N, 86.17° E occurred on June, 18 2013 near the Bachatsky coal strip mine, is the world’s largest earthquake induced while mining solid minerals. More than 5000 aftershocks were registered and the spatial volumetric structure of the aftershock area was investigated. The Bachat coal field is located in the Salair zone of the Kuznetsk Depression and is represented by a brachysynclinal fold of a very complex structure characterized by the damage and fracturing behaviors of rocks. The main event is confined to the coal-mine pit wall, with the greatest density of aftershocks observed in its middle portion. In the cross section, aftershocks form a wide area with its deepened portion shifted towards the Kuznetsk Depression, while large faults bounding the depression dip down under the Salair Ridge. In the exposed pit wall, at a depth of 4 km, the activated area resembles a rhombus whose horizontal diagonal line runs across the entire length of the mine pit and decreases both in upward and downward directions. The area is seismically activated to a depth of 6 km, with more intense activation of rock mass observed within the 1–3 km depth interval. Results of the study of the mechanisms of aftershock sources revealed a disagreement between the stress state of rock mass of the Bachatsky open-pit coal mine modeled from the mechanisms of aftershocks, and the mainshock mechanism of the Bachat earthquake.

Comparison of rehabilitation treatments on mechanically reconstructed soils following strip coal mining activities: effects on soil properties

A rainfed rehabilitation trial on mechanically reconstructed soil, following strip coal mining, was laid out in the Mpumalanga Province of South Africa. It was used to evaluate seven rehabilitation treatments with four different depths of topsoil on coal spoil over three experimental seasons. A strip plot design was used to apply the treatments. The test crop was a grass mixture comprising of annual and perennial species. Trial measurements included soil physical, chemical and microbiological measurements, as well as growth and composition of the grass stand. Monthly rainfall was very variable with annual totals below the long-term values. Statistical significance was proved for most measurements. Relatively high soil bulk densities, stratified with depth, were measured, indicating undesirable soil compaction. Infiltration rates increased while soil strength decreased dramatically with increased topsoil thickness. A reciprocal interaction of profile water content and biomass yield was observed with water content decreasing as biomass yield increased. A large variation in soil chemical properties was observed as a function of the treatments. This study highlights the fact that the monitoring of soil and plant properties should be a prerequisite in any rehabilitation study. Similar trials on different soils and in different rainfall regions should be considered to expand our knowledge of the impacts of different soil treatments in a range of ecosystems.

Specific features of thermal imaging surveys for detecting spontaneous combustion sources in coal strip mines

Specific features of thermal imaging surveys for detecting spontaneous combustion sources in coal strip mines

Thermal Recovery of Backfilled Pit in the Gulianhe Strip Coalmine in the Hola Basin in Northern Da Xing’Anling Mountains, NE China

In the northern Da Xing’anling Mountains in Northeast China on the southern margin of the Eastern Asia permafrost body, the ground thermal state and boreal ecological environment are sensitive to climate change and human activities. Since the 1980s, the Hola Basin here has been continuously and extensively developed. In particular, open pits and later backfilling in strip coal mining alters land–atmospheric hydrothermal exchanges in permafrost regions, leading to serious damages to the permafrost environment and boreal forest. After mining, pits need to be backfilled timely and properly for hydrothermal recovery of Xing’an permafrost and the boreal ecological environment. In this study, based on the comparative analysis of monitored ground temperatures in backfilled and undisturbed areas, influencing factors of thermal recovery after backfilling were analyzed through numerical simulations. Results show that the thermal recovery of permafrost in the backfilled area is closely related to temperature, depth, material, and soil moisture content of backfill. The warmer, finer, and thicker the backfill soils, the longer the permafrost recovery. Thermal recovery of permafrost also depends on the moisture content of backfill; the shortest recovery occurs at 15–25% in the backfilled soil moisture content. Based on numerical simulations and combined with enlightenments from features of the ecosystem-protected Xing’an permafrost in Northeast China, a composite configuration of organic soil, crush-rock layer, and proper re-vegetation measures is advised. Based on prudent regulation of heat transfer modes, this composite backfilling method can effectively cool the backfilled ground and can even possibly offset the climate warming.

Increasing life of pit dump truck motor-wheel gearboxes by introducing the monitoring of the actual technical condition

At present, Kuzbass coal strip mines pay great attention to improving quality performance of mining equipment operation, including reliability and durability of components and units. One of the ways of the performance improvement is decreasing number of unforeseen failures. To achieve this purpose a mine dump truck part diagnostics should be introduced into a maintenance service procedure. At the same time the process of diagnostics should not increase the machinery downtime, but effectively reveal a condition of motor-wheel gearboxes in the course of dump truck operation. The aim of the research is to increase the reliability and service life of motor-wheel gearboxes of large BelAZ dump trucks. Failure of a motor-wheel gearbox is a rare phenomenon, but the cost of a new gearbox can vary from 3.5 to 10 million rubles. That is why it is important to implement such methods of diagnostics, which allow revealing the condition of gearboxes in the shortest possible time and without disassembling corresponding units. Determination of the actual technical condition of motor-wheel gearboxes is possible by different methods: vibroacoustic; acoustic; thermal; physical and chemical analysis of spent operating materials. The studies showed that none of these methods can be used as a universal one. When justifying and selecting the most suitable method, different factors should be considered, including technological, or a combination of methods should be applied, which will reduce risks, but at the same time increase costs. It is necessary to develop a better diagnostic method based on the use of several methods simultaneously.

Grain size distribution of waste rock masses of Kuzbass coal strip mines

Grain size distribution as a structural characteristic of waste rock and bulk masses in the course of mining and construction works acquires quantitative values in the process of rock blasting and hauling of rock mass. Such physical-mechanical and structural-textural parameters of a rock mass, as the ultimate strength of rocks and rock mass, fracturing, diameter of the natural rock jointing, have a significant impact on the blasted rock mass grain size distribution. On the other hand, such characteristics as stability, permeability of waste rock masses largely depend on the lithology and grain size distribution of the loosened rocks composing waste rock dumps and their height distribution within a dump. The paper describes the findings of the study of the grain size distribution of waste rock masses of Kuzbass coal strip mines and the features of its spatial variations within the masses. The textures of the bulk masses and physical and technical properties of the stacked rocks were studied both at the Kuzbass waste rock sites and in laboratory conditions. The grain size distribution of the fine lump part of the dumps with the lump size up to 50 mm was investigated by sieve method according to GOST 12536–2014, and the medium and large lump part was studied using oblique photoplanimetry. The field observations showed that the bottom part of the rock dumps, dumped by peripheral bulldozer or excavator methods was composed of coarse fraction with average lump size of: d<sub>cr</sub> = 0.8–1 m, while the middle part, of rock lumps of d<sub>cr</sub> = 0.4–0.6 m, and the upper part, mainly of fine fraction with lump size of less than 0.1 m. The ratio of length, width, and thickness of the blasted rock lumps was 1:0.85:0.8, which corresponds to elongated-flattened shape of the lumps. This requires significant number of coordinates for describing the lump positions in the rock mass, as well as taking into account the moments of inertia when modeling the motion of such lumps until they reach a stable position. Up-to-date non-commercial or commercial software and corresponding hardware can be used to take into account non-isometric shape of the lumps when modeling their motion.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ УСТОЙЧИВОСТИ БОРТОВ УГОЛЬНЫХ РАЗРЕЗОВ ПОД ДЕЙСТВИЕМ РАСПРЕДЕЛЕННЫХ НАГРУЗОК

The open method of solid minerals winning occupies a significant place in the total opening of the mining complex deposits of the Republic of Kazakhstan. In the energy band, a prominent role belongs to the Ekibastuz coal basin, where a number of large coal strip mine operates. The level of subsurface, equal parts of spoil bank of the external and internal stripping after a while lead to complex problems of ensuring the stability and safety of mining operations. The location of large external rock dumps on the bead surface has a negative effect on the stability of the latter. The purpose of the work was to establish the degree of the external rock dump influence located on the bead surface on the stability of adjacent rock mass of the coalmine depending on the distance of the dump to the upper edge of the side. There was numerical simulation of stress-strain state of adjacent rock mass under action of distributed load from rock dump carried out. It has been shown that studies of any point stability of the array from this type of load should be carried out on the basis of elasticity and the use of the finite element method theory implemented in packages of programs oriented specifically to scientific and engineering applications. There are the methodology and results of numerical modeling of quantitative assessments of various sections stability of the side loaded with an external rock dump with a height of 160m presented on the example of «Ekibastuz» coal mine. Based on a certain theory of rock strength and the criteria for their discontinuity, limit estimates of the critical distance of the external rock dump from the upper edge of the side were obtained, at which the latter may lose stability.

Бачатское техногенное землетрясение 18 июня 2013 г. с ML=6.1, I0=7 (Кузбасс)

The Bachatsky earthquake of 18 June 2013 and a seismic activation of the same name coal strip mine, started several years before the earthquake and still persists today, have been studied using temporal local seismic arrays in the area. It was found experimentally that the seismic process area is closely connected to open workings, and the earthquakes are extend-ed from the working bed to a depth of 4-5 km. Adjacent to the mine depression sedimentary rocks were activated. The technogenic seismic regime is continuous and not stationary: intervals of background seismicity with relatively weak and seldom events are disturbed by bursts of activity with a rise in the magnitude of stronger earthquakes and frequency of occurrence of weak events. The seismic activation may last for 1–3 months. During the last five years, four seismic activations have been recorded, three of which were generated by large earthquakes of 09.02.2012, ML4.3; 04.03.2013, ML3.9; 18.06.2013, ML6.1. The last one was completed by a series of perceptible earthquakes with local magnitude of 3.0–3.5. The focal mechanism of the Bachatsky earthquake is a thrust fault with one of the motion planes corresponding to the anthropogenic impact. The earthquake flow forms a single process in the space with the b-value of the Gutenberg-Richter relationship different from the natural seismicity. The studied induced seismicity does not correspond to the structural regularities of natural seismicity in the Altai-Sayan mountain area. The findings prove that the Bachatsky earthquake and associated activation can be considered as man-made events.

“A cancer on the planet”: Mountaintop Removal and Environmental Crime in Jonathan Franzen’s Freedom

The American novelist Jonathan Franzen has always shown a great interest for the environmental problems, mainly in his masterpiece Freedom (2011) and in the essay “My Bird Problem” (2005). Freedom, which recounts three decades of the Berglund family, sees its main character dealing with the environmental themes for his work. Walter is a lawyer who is actively engaged in environmental causes, but the one that occupies most of the novel, is the support of an organization called “Cerulean Mountain Trust”, which aims at saving the cerulean warblers, a small species of songbird, creating a “birds’ sanctuary” in West Virginia. The honorable cause is actually moved by Vin Haven, a Texan millionaire tycoon who wants to implement an extractive coal strip mining operation and afterwards build the birds’ sanctuary as a remedial move. The aim of this paper is to analyze the novel to extract Franzen’s fictional depiction of actual environmental crimes in order to shed light on harmful practices such as the mountaintop removal.

Land-Use Conflicts in the Sudetes, Poland

The Sudetes (Polish and Czech: Sudety; German: Sudeten) are a mountain range located in the Czech-Polish-German border region with relatively high population density. In the paper we analyse the main type of land-use social conflicts in this region. In the 20th century, the conflicts and problems in the Sudetes were connected mainly with mineral resources exploitation, especially in black coal deep mines and brown coal strip mines. In the 21st century, the growing number of conflicts is caused by plans of ski infrastructure development and settlement growth in valuable nature areas, plans of constructing new quarries and wind power farms. The municipal local spatial management plans and investment plans are sometimes at variance with nature protection needs and focus on the immediate municipal budget income. There are difficulties with the promotion and implementation of alternative projects, which, taking into consideration nature protection, would also satisfy social needs. To promote compromises in spatial planning and to weaken or eliminate ecological conflicts we need to create stronger communication and negotiating networks of local inhabitants, local authorities and naturalists (both scientists and NGOs), and promote the role of alternative nature friendly conceptions at the early stage of spatial planning.

Creation of the Mammoth Park at Viminacium, Serbia

The Roman archaeological site of Viminacium, a cultural property of exceptional importance to the Republic of Serbia and a place on the UNESCO Tentative List, is located about 3 km south of the Danube, in arable fields near the “Kostolac B” thermal power plant and the strip coal mine “Drmno”, within the administrative borders of the City of Požarevac. In addition to the large number of cultural properties, there are many natural properties in the area of Požarevac, whose internationally recognised representatives are located right next to the Viminacium Archaeological Park. In the summer of 2009, in the strip coal mine “Drmno”, a mammoth skeleton was found, preserved almost entirely. Although different possibilities for such a skeleton to remain in the mine were considered, it was eventually decided to relocate it to a secure location within the Viminacium Archaeological Park and, in 2014, the construction of a purpose-built area under the name of The Mammoth Park began. Together with the future reclaimed areas of “Drmno” and its valuable geoheritage, the presented archaeological remains of Viminacium, other exceptionally important cultural and historical properties in the vicinity, the river Danube and other significant natural assets, The Mammoth Park can form a unique cultural landscape.

ГЕОМЕХАНИЧЕСКОЕ ОБОСНОВАНИЕ ГОРНОТЕХНИЧЕСКОЙ ОБСТАНОВКИ ПРИ ОТРАБОТКЕ ПЛАСТОВ КОМПЛЕКСОМ КГРП

One of the most effective methods when coal strip mine is entered into limiting contour is technology of drilling out of reserves located beyond technical boundaries (in sides) using complexes of deep seam development (KGRP). Due to minimal capital costs and reusing mine technical infrastructure, the method is described with high efficiency. However, the application is significantly limited due to broken condition of solid. In mining engineering, the main application area of KGRP complexes is side solids of coal strip mines, which are located in the zones of dumping rock jointing. Therefore, the objective of the paper is estimation of influence rate of solid broken condition on stability of coal strip mine side and actual mining (rooms and pillars). Solution of the objective is gained by using numerical finite-element simulation of geomechanical situation for typical conditions of coal strip mines. Investigation novelty consist in more complex consideration when solution of solid lithology is carried out, its broken condition, strain-strength properties, parameters of natural initial stress field and constructive features of extraction technology with forming of mine technical construction.

The Elaboration of the Technology of Polymalt Beverages Recommended to the Population of Kemerovo Region Under the Conditions of Negative Ecological Environment

The strained ecological situation in the whole world to a greater or lesser degree concerns the regions of Russia, including Kemerovo region. High level of this region’s industry (mines, coal strip mines, metallurgical plants, ect.) adversely impacts the atmospheric air first of all. According to the official data of Federal State Statistics Service the total pollutant emission into the atmosphere in 2017 exceeded the previous year by 9% in the same parameter, the exceeding of pollutants in the atmosphere concerns to a greater extent soot (carbon), nitrogen dioxide and carbon oxide. With the purpose of civil protection from dangerous effect of bad atmospheric air the bodies of authority take measures oriented to reducing of atmospheric emissions, meanwhile, every separate inhabitant should regulate his/her way of life individually and in such manner as to increase reinforce the immune system and body resistance to external nuisances. One of indispensible aspects which form a healthy lifestyle is a sensible nutrition. In the project there is represented the technology of natural grain beverages on the base of oat, soya, wheat and barley malts, possessing high concentration of protein, amino acids, vitamins and phenol compounds. There have been elaborated four receipts of beverages that are characterized by proportional composition of raw materials being used. The represented technology allows receiving beverages with high nutritious value owing to the content of strong concentration of nitrogen compounds and polyphenol substances allowing to suppress the influence of free radicals on organism and to remove heavy metals thus protecting human organism from aggressive environmental effect.

Assessment of current state of conserved areas of mountain rocks in strip mining conditions

In the conditions of the development of today´s mining industries, many coal mining enterprises (even though the production volumes are currently increasing) are looking for the ways to conserve previously mined areas and monitor their ecological state. The extraction of fossils from the depths of the earth produces natural and manmade complexes that have a considerable impact on vast territories. The largest impact lies in turning the lands for general use into commercial mining areas and land allocations. Open cut mining leads to the emergence of quarries, stopes and embankments of different sizes, changes in relevant and absolute elevation marks compared to the initial surface, which is connected with the construction of quarry dumping complexes. Direct dumping methods contribute to the formation of the system of narrow crests that are combined with leveled plateau-like parts of a spoil pile. The slopes of spoil piles have high angles of gradient (14-40°) and are subject to sheet and gully erosions which form large alluvial cones. Technogenic sediments formed at their bottom reach the height of several meters and spread up to a few hundred meters from the dumps. During coal mining, the rocks are stored in external and internal dumps of coal strip mines without any preliminary sorting, which also leads to soil and water pollution with heavy metals.

Thermal Analysis of Brown Coals from the Mugunsk Deposit

The results of the thermal analysis of brown coals from the Mugunsk coal strip mine (Irkutsk oblast) are reported. The number and sequence of the elementary steps of reactions occurring in coals on heating were determined.